Mohini Rawat, DPT, MS, ECS, OCS, RMSK
American Board of Physical Therapy Specialties Board Certified in
Clinical Electrophysiology and Orthopedics
Registered in Musculoskeletal Sonography, Alliance for
Physician Certification and Advancement
Director
Hands-On Diagnostics Services Fellowship Program in
Musculoskeletal Ultrasound
Cofounder & President
American Academy of Musculoskeletal Ultrasound

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Names: Rawat, Mohini, author.
Title: Atlas of musculoskeletal ultrasound of the extremities / Mohini
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Description: Thorofare, NJ : SLACK Incorporated, [2020] | Includes
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Identifiers: LCCN 2020011268 (print) | LCCN 2020011269 (ebook) | ISBN
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9781630916046 (web)
Subjects: MESH: Musculoskeletal System--diagnostic imaging |
Extremities--diagnostic imaging | Ultrasonography--methods | Atlas
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DEDICATION
This book is dedicated to my husband, Chirag, who is my best friend and best critic, and my
son, Etash, who is the light of my life.
To my parents, for always believing in me.
To my beautiful family and friends, for their support and well wishes.
To my patients, colleagues, mentees, and students.
To the many experts and professionals across the globe who continue to inspire me with their
knowledge and work.

CONTENTS
Dedication . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .ix
About the Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xi
Contributing Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xiii
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv
Foreword by Dimitrios Kostopoulos, DPT, MD, PhD, DSc, ECS . . . . . . . . . . . . . . . . . . . . . . . . . . xvii
Foreword by Kornelia Kulig, PhD, PT, FAPTA . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xix
Chapter 1

Introduction to Musculoskeletal Ultrasound Imaging . . . . . . . . . . . . . . . . . . . . . . . . 1
Gina A. Ciavarra, MD

Chapter 2

Wrist and Hand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Mohini Rawat, DPT, MS, ECS, OCS, RMSK and Mukund Patel, MD, FACS

Chapter 3

Elbow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Mohini Rawat, DPT, MS, ECS, OCS, RMSK

Chapter 4

Shoulder . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81
Mohini Rawat, DPT, MS, ECS, OCS, RMSK

Chapter 5

Ankle and Foot . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115
Mohini Rawat, DPT, MS, ECS, OCS, RMSK

Chapter 6

Knee . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159
Mohini Rawat, DPT, MS, ECS, OCS, RMSK

Chapter 7

Hip . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201
Mohini Rawat, DPT, MS, ECS, OCS, RMSK

Chapter 8

Peripheral Nerves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 231
Mohini Rawat, DPT, MS, ECS, OCS, RMSK

Financial Disclosures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 289

ACKNOWLEDGMENTS
I would like to thank my brother, Aashish, for his assistance with the photographs for the book.
This book would not be possible if my paths had not crossed with my mentors, Dr. Kornelia
Kulig, Dr. Dimitrios Kostopoulos, and Dr. Mukund Patel.
My interest in imaging sparked during my time in graduate school at the University of Southern
California (Los Angeles, California) under Dr. Kulig, and Dr. Kostopoulos was the wind beneath
my wings in the clinical world. I am forever grateful to Dr. Mukund Patel for his guidance
and learning opportunities. Working with him was like drinking directly from the fountain of
knowledge.

ABOUT THE AUTHOR
Mohini Rawat, DPT, MS, ECS, OCS, RMSK is cofounder and president of the American
Academy of Musculoskeletal Ultrasound. She is fellowship director of the Musculoskeletal
Ultrasound Program at Hands-On Diagnostics. She is board certified in clinical electrophysiology
and orthopedics by the American Board of Physical Therapy Specialties and in musculoskeletal
sonography by the Alliance for Physician Certification and Advancement. She received her doctorate in Physical Therapy from Massachusetts General Hospital Institute of Health Professions in
Boston, Massachusetts, and her master’s degree in biokinesiology from the University of Southern
California. She is faculty for courses in musculoskeletal ultrasound and clinical electrophysiology in the Physical Therapy Program and other continuing education courses. She has mentored
hundreds of clinicians and has reviewed thousands of ultrasound studies. Dr. Rawat has been a
contributing author and written chapters on imaging in books. She has published articles and presented numerous musculoskeletal ultrasound courses, webinars, and lectures in multiple professional conferences and organizations, including the American Institute of Ultrasound in Medicine
and American Academy of Orthopaedic Surgeons annual meeting.
This book presents her passion for ultrasound imaging as a clinical tool, as she takes the reader
through the journey of rediscovering anatomy with detailed illustrations and descriptive ultrasound images.

CONTRIBUTING AUTHORS
Gina A. Ciavarra, MD (Chapter 1)
Clinical Associate Professor of Radiology
New York University Langone Health
New York, New York
Dimitrios Kostopoulos, DPT, MD, PhD, DSc, ECS (Foreword)
American Board of Physical Therapy Specialties Board Certified in Electromyography-Nerve
Conduction Studies Testing
Clinical Affiliate Assistant Professor
College of Medicine
Florida Atlantic University
Boca Raton, Florida
Cofounder
Hands-On Companies
Astoria, New York
Kornelia Kulig, PhD, PT, FAPTA (Foreword)
Professor
Co-Director
Musculoskeletal Biomechanics Research Laboratory
Division of Biokinesiology and Physical Therapy
Herman Ostrow School of Dentistry
University of Southern California
Los Angeles, California
Mukund Patel, MD, FACS (Chapter 2)
Fellow
American College of Surgeons
Chicago, Illinois
Emeritus Associate Clinical Professor of Orthopedics
New York University Medical School
New York, New York
Emeritus Associate Clinical Professor of Orthopedics
Downstate Medical Center
State University of New York
New York, New York

PREFACE
Truth is ever to be found in simplicity, and not in the multiplicity and confusion of things.
—Isaac Newton
This book is an attempt to offer pragmatic approaches in the ever-growing field of ultrasound
as a point-of-care tool. Ultrasound is safe, noninvasive, cost-effective, and an efficient point-ofcare tool in the hands of clinicians but requires in-depth understanding of anatomy. Knowledge
of anatomy here is fundamental to the precise application of this modality. Your ultrasound image
acquisition and interpretation skills are limited by your understanding of 3-dimensional anatomy
of the neuromusculoskeletal system. Keep in mind not just where to find the structure but the
course and fiber orientation of the structure of interest. This book provides detailed anatomical
illustrations of imaging regions with key points highlighted to shorten this learning curve.
I present to you the Atlas of Musculoskeletal Ultrasound of the Extremities with the sincere hope
that you will find this book helpful in enhancing your understanding of neuromusculoskeletal
ultrasound imaging. The book has easy-to-follow sections that can be used to create tailor-made
scanning protocols based on clinical needs.

FOREWORD
When Dr. Rawat approached me about writing a foreword for her book, I felt both a deep sense
of pride and an undefinable elation. Here was someone whom I respected professionally and whose
work I admired, and to learn that she had completed her manuscript and that I was going to be a
part of it … well, it is not often in life that one receives 2 wonderful pieces of news at the same time.
A board-certified electrophysiology specialist and board certified in musculoskeletal ultrasound, Dr. Rawat is a person who wears many hats. She has conducted and published impressive
research with regard to clinical electrophysiology, all of which I have followed closely and admiringly. In addition to that—which would certainly be enough to keep almost anyone busy—she
teaches seminars and guest lectures at multiple university programs in the New York metropolitan
area. Suffice to say that she puts in her dues.
My own relationship with Dr. Rawat dates back nearly a decade. I met her in April 2011, when
she became a clinical associate at Hands-On EMG Testing, and right from the start, I could tell
that there was something special about her. She stood out even in a crowd of capable, talented
medical professionals; her intelligence is tremendous, and her work ethic is beyond reproach.
What I remember most vividly from my earliest days with Dr. Rawat, however, is how kind
she was. I saw the effect that she had on the people around her, and as ambitious and focused as
she was, she was also looking out for others and making time for them if they needed her for one
thing or another.
I always admired Dr. Rawat’s demeanor, and when she started teaching, I thought, “Yes, that
makes sense,” because her heart is that of a teacher: forever giving and looking out for everyone
around her.
To her patients, Dr. Rawat is a friendly smile and a steady hand. She is adept at guiding her
patients through the treatment that she is providing them and empowering them to know themselves better by communicating their conditions to them with clarity and precision. This, too, is
something I admire about her because I know how frustrating a process it can be.
Today, Dr. Rawat is the fellowship program director of Musculoskeletal Ultrasound Studies at
Hands-On Diagnostics and cofounder and president of the American Academy of Musculoskeletal
Ultrasound. It bears repeating: She does know how to stay busy.
I believe that Dr. Rawat has outdone herself in this book, which could prove to be an invaluable resource for sonographers, student sonographers, physicians, physical therapists, and other
medical professionals. Of course, even before I read it, I could have told you that it was going to
be outstanding.
Dr. Rawat is a thought leader in our field, and the clinical revolution she has spearheaded is
nothing short of remarkable, altering the way we think of musculoskeletal ultrasound imaging
studies and helping to make them the purview of physical therapists everywhere.

xviii

Foreword

From step-by-step protocols to incisive explanations, this book contains a treasure trove of
information and analysis, and on every page, I can hear Dr. Rawat’s voice ringing in all its kindness and humble acuity. The images as well are second to none, clearer and more vivid than any I
have ever seen before.
Whether you read this book as I did—for pleasure and smiling the entire time—or as a student,
I hope that you get out of it everything that it has to offer.
—Dimitrios Kostopoulos, DPT, MD, PhD, DSc, ECS
American Board of Physical Therapy Specialties Board Certified in Electromyography-Nerve
Conduction Studies Testing
Clinical Affiliate Assistant Professor
College of Medicine
Florida Atlantic University
Boca Raton, Florida
Cofounder
Hands-On Companies
Astoria, New York

FOREWORD
Ultrasonography has a firm presence in musculoskeletal imaging and continues to aid clinicians in differentially diagnosing conditions with diverse signs and symptoms. Unlike other
imaging modalities, ultrasonography requires the operator to deeply understand and implement
3-dimensional anatomy relevant to the subject’s symptoms and body position. That cognitive and
motoric skill develops over time with exposure to focused anatomical studies, training under the
guidance of an instructor, and access to exceptional visual and descriptive anatomical resources.
There has been a void for a detailed visual and descriptive anatomical and procedural resource
that this book fills.
This book artfully blends an in-depth anatomical knowledge with skillful, clinically motivated
ultrasonographical practice and, by doing so, paints a clear path of application of anatomy to
practice. It is evident that this work stems from a labor of love of the content, extensive clinical
experience, and professional commitment to sharing knowledge with a diverse group of learners.
In this beautifully illustrated book, readers will find a very clear how-to and why-to use of ultrasonography in musculoskeletal practice. This book will be of great use to clinicians with diverse
academic backgrounds: orthopedists, neurologists, physical therapists, occupational therapists,
and athletic trainers. This book is also a guide for those who wish to rediscover anatomy in its life
form, which may rekindle the love of anatomy and its application to patient care.
—Kornelia Kulig, PhD, PT, FAPTA
Professor
Co-Director
Musculoskeletal Biomechanics Research Laboratory
Division of Biokinesiology and Physical Therapy
Herman Ostrow School of Dentistry
University of Southern California
Los Angeles, California

1
Introduction to
Musculoskeletal Ultrasound
Imaging
Gina A. Ciavarra, MD

INTRODUCTION TO ULTRASOUND PHYSICS
Ultrasound is distinct from other imaging modalities in that it uses sound waves rather than
ionizing radiation to create images. One of the major components of the ultrasound machine is
the transducer, or probe, which serves as the primary contact point between the patient and the
sonologist as well as the ultrasound machine. A transducer is any device that converts one form
of energy into another. In the case of the ultrasound transducer, electrical energy is converted
to ultrasound waves, and vice versa.1,2 The ultrasound probe comprises multiple piezoelectric
elements (crystals), which produce the piezoelectric effect that allows this conversion between
electrical signal and ultrasound energy. When an electrical signal is transmitted to the transducer,
the crystals vibrate at a particular frequency. As the crystals vibrate, a sound wave is created and
transmitted into the patient. After the sound wave reflects back to the transducer from the patient,
the crystals again vibrate, causing an electrical signal, which can then be converted into an ultrasound image. The crystals can be designed so that they will vibrate at a specified frequency. Within
the patient, the sound waves may be reflected at soft tissue interfaces back toward the transducer as
described, absorbed by the tissue interface, or refracted.1,3 Refraction is the bending of the sound
wave as it passes through tissue interfaces that exhibit differing ultrasound propagation speeds (eg,
fluid to muscle or soft tissue to bone).3 It is those ultrasound waves, or echoes, reflected back to
the transducer that are converted into the electrical signals that ultimately become an ultrasound
image. Ultrasound waves transmitted perpendicular to the surface of the object of interest will
be reflected more than nonperpendicular waves. Therefore, for optimal imaging, the structure of
interest should be imaged at an angle perpendicular to the probe.3
Coupling or acoustic transmission gel is used to promote the transmission of sound waves
into the patient. The gel is positioned between the patient’s skin and the transducer to eliminate
air between the 2 surfaces. The introduction of air between the transducer and patient impedes
transmission of the sound waves because the air causes reflection of the sound waves at the skin’s
surface, thus preventing the waves from entering the patient and resulting in a degraded image or
no image at all.3
-1-

Rawat M.
Atlas of Musculoskeletal Ultrasound of the Extremities (pp 1-12).
© 2021 SLACK Incorporated.

2

Chapter 1

ULTRASOUND EQUIPMENT/PROBES
When selecting a transducer, the sonologist has to consider what is the optimal frequency of
the transducer based on the depth of the structure of interest because the frequency determines
the image quality and penetration. Each transducer possesses the capability to produce a range of
sound frequencies measured in megahertz (MHz). Higher-frequency transducers are able to produce images of higher resolution. Unfortunately, this comes at the expense of penetration of the
sound waves through the tissues. Thus, high frequency transducers are best suited to assess more
superficial structures (eg, tendons of the hand and wrist). Lower-frequency transducers are better
able to penetrate the soft tissues and therefore better suited to evaluate deeper structures (eg, hip
joint); however, this results in lower resolution (Figure 1-1).1,3

B

A
Figure 1-1. Ultrasound images obtained with different
transducers. (A) Hip injection with curvilinear probe.
Note the conical shape of the beam and curvature at the
surface (white arrow). (B) Patellar tendon (white arrow)
obtained with a linear probe. Note the rectangular shape
of the beam. (C) Ulnar nerve (N) perineural injection
obtained with a hockey stick probe. The small surface
and curvature of the bone (B) make this probe an ideal
choice. Needle (white arrow) and anesthetic (a).

C

Additional considerations include the shape and size of the transducer. The 2 most common
types of transducer designations are linear and curvilinear. The linear transducer is optimal for
assessment of linear structures (eg, tendons and ligaments) and for use along relatively flat surfaces
such as the extremities. The sound waves transmitted from the linear probe propagate parallel
to the probe surface and result in a rectangular image. With a curvilinear probe, the ultrasound
waves transmit in a radial path from the probe surface, resulting in a wider field-of-view (FOV)
image as compared with the linear probe. An additional type of linear probe with a small footprint
(sometimes called a hockey stick probe due to its shape) is especially useful in imaging small structures in the hand, wrist, foot, and ankle (Figure 1-2).1-3

Introduction to Musculoskeletal Ultrasound Imaging
A

B

3

C

Figure 1-2. (A) Curvilinear, (B) linear, and (C) hockey stick (small footprint) ultrasound transducers.

The availability of the different probes and capabilities of individual ultrasound machines
vary based on size, power, and cost. Larger ultrasound systems have more powerful computing
capabilities and allow for the use of ultrahigh frequency transducers, resulting in high-resolution
images of superb quality. Smaller, more portable machines, which may be the size of a briefcase,
are also available. These have the advantages of lower cost and portability but are more limited
in their ability to produce high-resolution images and have fewer advanced applications (eg, realtime fusion with computed tomography scan/magnetic resonance imaging). As the technology
continues to advance, the technological differences between the 2 types of machines will become
less pronounced.2

SCAN TECHNIQUE/IMAGE APPEARANCE
When the transducer is placed on the patient and an image is created, the more superficial
structures are those closest to the transducer along the superior aspect of the image. The deeper
structures, farthest from the transducer, are along the inferior aspect of the image. Typically,
when imaging a structure in long axis, the convention is to have the more proximal aspect of the
structure to the left side of the image and the more distal aspect to the right. The most important
point is to be consistent across imaging studies. The left and right sides of the image can be easily switched by using the invert button on the ultrasound machine or by rotating the probe 180
degrees.2
Once oriented, the sonologist should optimize the image to improve the resolution and visualization of the structure in question. This begins even before initiating the study with appropriate
probe selection. As discussed, higher-frequency transducers are preferred for the evaluation of
more superficial structures (eg, hand, wrist), whereas lower-frequency transducers are preferred
for deeper structures (eg, hamstring origins, hip joint). Linear transducers are preferred unless
evaluating a deeper structure, where the lower-frequency curvilinear probe is preferable.1,3
After selecting the appropriate probe, the image should be optimized using some of the buttons
available on the ultrasound machine. First, the depth of the ultrasound beam should be adjusted.
This is accomplished by ensuring that the object of interest is centered within the image. Second,
the number of focal zones should be adjusted. An ultrasound beam is narrowed, or focused, not
simply at one point but over a range of depths also known as a focal zone. More specifically, a
focal zone is defined as a range of depths over which the ultrasound beams are most narrowed (or
focused). The number of focal zones should be adjusted to include the fewest number of focal zones
while encompassing the entire region of interest being scanned such that the ultrasound beam

4

Chapter 1

is most focused on the target structure, improving image resolution. Once the number of focal
zones is selected, the depth should also be adjusted to optimize evaluation of the object of interest
as previously discussed (Figure 1-3). Finally, the gain, or image brightness, should be modified to
improve the image quality. Because different tissues attenuate the sound waves to varying degrees,
adjusting the gain can optimize the image to account for these differences, resulting in a more
uniform appearance of the image.2,3

B
A

D
Figure 1-3. Adjusting the depth and focal zones (median
nerve). (A) Suboptimal depth (D) and focal zone (FZ)
result in a blurry image with poorly centered median
nerve (MN). (B) Depth (D) has been improved for better
C
centering of the nerve (MN), but image remains blurry
due to suboptimal focal zone (FZ). (C) Optimal focal zone (FZ) improves blurriness of the median nerve (MN), but
poor depth (D) selection results in poorly centered nerve. (D) Both depth (D) and focal zone (FZ) are optimized with
improved image quality of the median nerve (MN).

Introduction to Musculoskeletal Ultrasound Imaging

5

TERMINOLOGY
In evaluating the musculoskeletal system, it is important to be aware of the principal terms
used to describe and differentiate the various structures. The term hyperechoic or echogenic is
used to describe structures that appear bright on the image in the musculoskeletal system. These
structures include normal tendons and the surface of the bone, as well as soft tissue calcifications.
The term hypoechoic refers to structures that produce fewer reflected echoes and appear less bright
within the image. These structures include muscle, certain soft tissue masses, and complex fluid
collections. A structure that produces no echoes is termed anechoic and appears black within the
image. Simple cysts or fluid collections are typically anechoic. The term isoechoic is used to refer
to a structure that is of similar echogenicity to the surrounding structures. An example of an
isoechoic structure may include a lipoma within the subcutaneous fat (Figure 1-4).2-5

A
B

C
Figure 1-4. Echogenicity in ultrasound. (A) This foreign
body (FB) is hyperechoic, or bright. (B) This soft tissue
sarcoma (S) is hypoechoic, or less bright, due to fewer
reflected echoes. (C) A simple cyst (small white C) is
anechoic, producing no echoes. (D) Lobules of fat within
this Morel-Lavallée lesion (L) may be isoechoic to the
adjacent subcutaneous fat (F).

D

6

Chapter 1

NORMAL STRUCTURES
The appearance of normal structures in the musculoskeletal system will be discussed in more
depth in later chapters. In order to understand one of the more relevant artifacts in musculoskeletal imaging, however, it is important to be cognizant of the normal appearance of tendons.
Tendons comprise multiple individual, longitudinally oriented, parallel collagen fibers that are
tightly bundled, resulting in a fibrillary pattern on ultrasound. This results in the characteristic
hyperechoic appearance of tendons when the ultrasound beam is oriented 90 degrees to the tendon
(Figure 1-5).2,4,5
Figure 1-5. Normal tendon. The
biceps tendon (BT) imaged in long
axis demonstrates the characteristic
fibrillary pattern of tendons and is
hyperechoic.

IMAGING ARTIFACTS IN ULTRASOUND
Although there are a number of sonographic artifacts, there are several important artifacts
that the sonologist should be aware of in order to make an accurate diagnosis, as well as to avoid
mistaking artifact for pathology:
• The most well-recognized artifact in musculoskeletal imaging is anisotropy. The normal
appearance of tendons is hyperechoic with a fibrillar pattern.4,5 This results from the individual fibers that comprise the tendon. This appearance occurs when the tendon is imaged at
an angle perpendicular to the ultrasound beam. If the beam is positioned at an angle less than
or greater than 90 degrees, the tendon will appear falsely hypoechoic, mimicking pathology.
This characteristic of tendons is known as anisotropy (Figure 1-6). Ligaments also exhibit
anisotropy when imaged at an angle other than 90 degrees.2,4,5

A

B

Figure 1-6. Anisotropy. (A) The supraspinatus tendon is imaged with the transducer beam perpendicular to the
tendon (T) and (B) at an angle less than 90 degrees, resulting in loss of fibrillar pattern (white arrow) and mimicking
tendinosis.

Introduction to Musculoskeletal Ultrasound Imaging

7

• Another artifact is shadowing. This is the result of reflection, absorption, or refraction of an
ultrasound beam at an interface. This produces a dark (hypoechoic) or anechoic region deep
to the interface, which may obscure structures within the path of the shadow. Within the
musculoskeletal system, this occurs most commonly with bone or calcification (Figure 1-7).6,7
Figure 1-7. Shadowing. Calcification
(Cal) within the rectus femoris tendon
produces a dark area (white arrow)
deep to it due to reflection and/or
absorption of ultrasound beams at
the surface.

• Posterior acoustic enhancement occurs when imaging fluid or certain soft tissue tumors.
These structures result in decreased attenuation of the ultrasound beam when compared with
the surrounding tissues. Accordingly, the tissues deep to the fluid will appear more echogenic
because more of the incident beam will pass through (Figure 1-8).3,6
Figure 1-8. Posterior acoustic
enhancement. Note how the tissues
deep to the cyst (C) overlying the
radius (Rad) are brighter (large white
arrow), with septation in cyst (small
white arrow).

8

Chapter 1

• Finally, posterior reverberation and ring-down artifact are 2 additional artifacts that one may
encounter in the musculoskeletal system. Reverberation (Figure 1-9) occurs when the sound
beam reflects repeatedly between the transducer and a parallel surface, such as bone, or a
metal object, such as a foreign body or surgical device (eg, clip, fixation plate). The resulting
images display as multiple linear echoes deep to the imaged surface at equally spaced intervals. A subtype of reverberation is known as ring-down artifact. When the reflection of the
sound beam is highly efficient, such as with gas bubbles in fluid or metal hardware, a series
of bright echoes will be displayed in deeper tissues posterior to the bubble or metal structure
(Figure 1-10).3,6,7
Figure 1-9. Reverberation artifact.
Sound beam reflects between the
transducer and the surface of the
metacarpal bone with multiple
linear echoes (white arrows).
(MC = metacarpal
of
thumb;
PP = proximal phalanx of thumb;
UCL = ulnar collateral ligament.)

Figure 1-10. Ring-down artifact.
Series of bright echoes (white arrows)
deep to metal screws (SC).

Although there are other artifacts that may be encountered in ultrasound, the aforementioned
are the most commonly encountered when imaging the musculoskeletal system.

Introduction to Musculoskeletal Ultrasound Imaging

9

ENHANCED ULTRASOUND TECHNIQUES
More recent enhancements in ultrasound imaging have allowed for further reduction in imaging artifacts. Compound or spatial compound imaging has allowed for improved imaging at tissue
boundaries or the edge of the structure of interest. With compound imaging, multiple images
are created in succession and merged to form a single image. This allows for better evaluation of
curved structures. Compound imaging also reduces speckle or “noise” in the image, resulting in a
smoother imaging appearance (Figure 1-11).3,8

A

B

Figure 1-11. Compound imaging. Use of compound imaging in (A) results in a smoother image of the supraspinatus
tendon (ST), as compared with (B), which demonstrates speckle, or noise.

When an ultrasound beam enters the patient, it creates multiple echoes as it interacts with
the tissues it is traversing. These reflected echoes may be useful to the sonologist to improve the
quality of the image. Tissue harmonic imaging, a feature available on most ultrasound machines,
enhances image quality by incorporating these additional reflected echoes that have been distorted
as they interact with the surrounding tissues. These beams are not contained in the original echo
but may be added to the original echo, strengthening it and thereby resulting in higher image
contrast and an improved signal-to-noise ratio (Figure 1-12).3,9

A

B

Figure 1-12. Tissue harmonic imaging. Use of tissue harmonic imaging in (A) results in higher image contrast and
better signal-to-noise ratio with better visualization of the median nerve (MN) than in (B), obtained without tissue
harmonic imaging.

10

Chapter 1

Many ultrasound machines have the ability to employ chroma tints, which allow for colorcoding of the grayscale image hues using a variety of colors, such as red, sepia, and others. Because
the human eye has greater ability to perceive different shades of color rather than various shades
of gray, use of chroma mapping allows for better visualization of subtler soft tissue details. In the
musculoskeletal system, this is most useful in the evaluation of soft tissue masses (eg, vascular
malformations, neuromas) and nerves (Figure 1-13).10

A

B

Figure 1-13. Chroma tints. There is improved contrast resolution with decreased noise in this soft tissue mass (M)
using (A) chroma when compared with (B) grayscale.

Because ultrasound has a FOV, this limits evaluation of larger structures and their relationships
with the surrounding tissues. Extended FOV imaging allows the FOV to be enlarged by creating a
panoramic image. This is achieved by moving the transducer over the structure of interest with the
generation of multiple sequential images, which are combined to create the extended view without
loss of image quality (Figure 1-14).3,11,12
Figure 1-14. Extended FOV imaging.
Allows for visualization of the entire
Achilles tendon (A) from the calcaneus
(CC) to the myotendinous junction
(MTJ).

Introduction to Musculoskeletal Ultrasound Imaging

11

DOPPLER IMAGING
The most commonly used forms of Doppler imaging are color and power. Doppler imaging
employs the concept of the Doppler effect, which describes the change in frequency of the sound
wave as the object (source) moves toward or away from the receiver (transducer). The amount of
the change in frequency is known as the Doppler shift. The amount of this shift is dictated by the
speed of the movement of the source. By measuring this change, the speed of the source can be
determined. The most common use of Doppler in musculoskeletal imaging is to determine the
presence of blood flow in the structure of interest, such as in a soft tissue mass, and occasionally
the direction or type of flow (eg, within vascular malformations).3,13
Color-flow Doppler creates a 2-dimensional image superimposed on the grayscale image, where
information about the Doppler shift is assigned a color (red or blue) to indicate the direction of
flow (ie, blood flowing toward or away from the transducer, respectively). This technique does
not allow for the measurement of the velocity of blood flow (Figure 1-15).3,13 Another technique,
power Doppler, results in the measurement of the strength of the Doppler signal emanating from
the sample volume of blood evaluated. The image is created in a similar manner to the color-flow
Doppler image, but instead assigns color based on the strength of the Doppler signal. Because the
power mode is more sensitive than conventional color Doppler, it can detect significantly lower
flow. Because detecting the mere presence of flow is generally more important in most musculoskeletal cases than assessing the direction of flow (unlike in abdominal imaging), power Doppler
is used more frequently (Figure 1-16). Power Doppler is also not subject to aliasing artifact, a result
of undersampling.3,12,14
Figure 1-15. Color Doppler imaging.
Color Doppler image of a forearm
pseudoaneurysm
demonstrates
blood flowing toward (red) and away
from (blue) the transducer.

A

B

Figure 1-16. Power Doppler imaging. (A) Grayscale and (B) power Doppler images of a metacarpophalangeal joint
demonstrating synovitis (Syn) with hyperemia (H). The increased sensitivity of power Doppler allows for detection
of low flow in small joints.

12

Chapter 1

Pulsed-wave or duplex Doppler allows for the measurement of the velocity of blood flow within
a single sample volume by using short pulses of sound waves as opposed to the continuous sound
waves generally used in standard Doppler ultrasound imaging. The information may then be displayed graphically as a spectral waveform.3,12,13

REFERENCES
1.
2.
3.
4.
5.
6.
7.
8.

9.
10.
11.
12.
13.
14.

Hangiandreou NJ. AAPM/RSNA physics tutorial for residents. Topics in US: B-mode US: basic concepts and
new technology. Radiographics. 2003;23(4):1019-1033.
Jacobson JA. Fundamentals of Musculoskeletal Ultrasound. 3rd ed. Philadelphia, PA: Elsevier; 2018.
Gill R. The Physics and Technology of Diagnostic Ultrasound: A Practitioner’s Guide. Sydney, Australia: High
Frequency Publishing; 2012.
Martinoli C, Derchi LE, Pastorino C, Bertolotto M, Silvestri E. Analysis of echotexture of tendons with US.
Radiology. 1993;186(3):839-843.
Crass JR, van de Vegte GL, Harkavy LA. Tendon echogenicity: ex vivo study. Radiology. 1988;167(2):499-501.
Scanlan KA. Sonographic artifacts and their origins. AJR Am J Roentgenol. 1991;156(6):1267-1272.
Rubin JM, Adler RS, Bude RO, Fowlkes JB, Carson PL. Clean and dirty shadowing at US: a reappraisal.
Radiology. 1991;181(1):231-236.
Lin DC, Nazarian LN, O’Kane PL, McShane JM, Parker L, Merritt CR. Advantages of real-time spatial compound sonography of the musculoskeletal system versus conventional sonography. AJR Am J Roentgenol.
2002;179(6):1629-1631.
Strobel K, Zanetti M, Nagy L, Hodler J. Suspected rotator cuff lesions: tissue harmonic imaging versus conventional US of the shoulder. Radiology. 2004;230(1):243-249.
Sloves JM, Almeida JI, Sanchez Aguirre, PG, Abi-Chaker AM. Venous diagnostic tools. In: Almeida JI, ed. Atlas
of Endovascular Venous Surgery. 2nd ed. Philadelphia, PA: Elsevier; 2018:63-120.
Weng L, Tirumalai AP, Lowery CM, et al. US extended-field-of-view imaging technology. Radiology.
1997;203(3):877-880.
Klauser AS, Peetrons P. Developments in musculoskeletal ultrasound and clinical applications. Skeletal Radiol.
2010;39(11):1061-1071.
Boote EJ. AAPM/RSNA physics tutorial for residents. Topics in US: Doppler US techniques: concepts of blood
flow detection and flow dynamics. Radiographics. 2003;23(5):1315-1327.
Bude RO, Rubin JM. Power Doppler sonography. Radiology. 1996;200(1):21-23.

2
Wrist and Hand
Mohini Rawat, DPT, MS, ECS, OCS, RMSK and Mukund Patel, MD, FACS

Contents
• Volar Wrist
º Carpal Tunnel and Its Structures
º Structures Outside the Carpal Tunnel
º Volar-Radial Aspect of the Wrist
º Volar-Ulnar Aspect of the Wrist
• Dorsal Wrist
º Six Dorsal Compartments (Tendons From Radial to Ulnar Aspect)
• Distal Radioulnar Joint
• Scapholunate Ligament
• Triangular Fibrocartilage Complex
• Hand and Digits
º Volar Aspect
º Dorsal Aspect
º Collateral Ligaments of Proximal Interphalangeal Joint
º Ulnar and Radial Collateral Ligaments of First Metacarpophalangeal Joint
º Hand Muscles and Associated Tendons
º Carpometacarpal Joints

- 13 -

Rawat M.
Atlas of Musculoskeletal Ultrasound of the Extremities (pp 13-48).
© 2021 SLACK Incorporated.

14

Chapter 2

VOLAR WRIST
Carpal Tunnel and Its Structures
Anatomy of the region is shown in Figure 2-1.

A

Figure 2-1. (A) Structures inside the carpal tunnel. The flexor retinaculum (grey) forms the roof of the carpal tunnel.
The median nerve (yellow) is the most superficial structure just beneath the flexor retinaculum. Flexor tendons lie
underneath the median nerve. The floor of the carpal tunnel is formed by carpal bones (brown). (continued)

Wrist and Hand

15

B

C

Figure 2-1 (continued). (B) Cross-sectional anatomy at the proximal carpal tunnel. (C) Cross-sectional anatomy at the
distal carpal tunnel. (FCR = flexor carpi radialis; FPL = flexor pollicis longus; MN = median nerve; P = flexor digitorum
profundus tendons; S = flexor digitorum superficialis tendons.)

16

Chapter 2

1. Patient position: Sitting or in supine with wrist in full supination and resting on the table
2. Probe/transducer position:
a. Short axis (SX) view/transverse view: Use the pisiform as a bony landmark for the SX/
transverse view of the carpal tunnel.
b. Long axis (LX) view/longitudinal view: Once you locate the median nerve in the SX view,
keeping the nerve in focus, rotate the probe 90 degrees to see the LX view of the median
nerve (Figures 2-2 through 2-4).

A

B

C

Figure 2-2. (A) Probe placement for
the SX view of the median nerve. (B) SX
view of the carpal tunnel at the level
of the pisiform. (C) Labelled SX view
of the carpal tunnel at the level of the
pisiform. On the radial side: FCR outside
the carpal tunnel, FPL radial-most in
the carpal tunnel, flexor tendons (T)
in the carpal tunnel underneath the
median nerve (larger yellow circle). Outside the carpal tunnel on the ulnar side: ulnar nerve (smaller yellow circle) and
ulnar artery (red circle).

Wrist and Hand
A

17

B

Figure 2-3. (A) Probe placement for the LX view of the median nerve. (B) LX
view of the carpal tunnel: The median nerve appears as a hypoechoic band
overlying hyperechoic fibrillar flexor tendons.

A

Figure 2-4. (A) Proximal carpal tunnel anatomy and ultrasound image. (continued)

18

Chapter 2

B

Figure 2-4 (continued). (B) Distal carpal tunnel anatomy and ultrasound image. The FCR can be seen deep in the
medial groove of the trapezium in its own compartment. (A = ulnar artery; MN = median nerve; P = flexor digitorum
profundus tendons; PL = palmaris longus; S = flexor digitorum superficialis tendons.)

Wrist and Hand

19

3. Relevant anatomy: From superficial to deep, structures in the carpal tunnel are arranged in
the order of skin, subcutaneous layer, flexor retinaculum (roof of the carpal tunnel), median
nerve, flexor tendons, and carpal bones (floor of the carpal tunnel).
4. Points to remember: A cross-sectional area of median nerve more than 10 mm2 at the level of
the pisiform is considered abnormal.1
Median nerve mobility in the carpal tunnel can be assessed with dynamic examination as
the patient flexes and extends the fingers and wrist. Median nerve mobility is negatively correlated with severity of the carpal tunnel syndrome.2,3
Subsynovial connective tissue, which appears as a hypoechoic nonmoving layer surrounding the flexor tendons under the flexor retinaculum, is thicker in patients with carpal tunnel
syndrome than in normal healthy controls (Figure 2-5).4,5
Figure 2-5. Subsynovial connective
tissue is a hypoechoic interface
(between cursors) bound by the
hyperechoic
thin
boundaries
between the nerve on top and flexor
tendons below.

Anomalies are common in the wrist. Some of the anomalies that may be present in wrist
scans are bifid median nerve, persistent median artery, anomalous muscle of forearm in
carpal tunnel (eg, flexor digitorum superficialis [FDS]), anomalous muscle of hand in carpal
tunnel (eg, lumbrical muscle), and reverse palmaris longus (rare).6
Sonoelastography is a newer area in ultrasound where stiffness of the structure is assessed.
It has been reported that stiffness of the intracarpal tunnel structures in carpal tunnel syndrome is higher than in the healthy controls.7

20

Chapter 2

Structures Outside the Carpal Tunnel
1. Patient position: Sitting or in supine with wrist in full supination and resting on the table
2. Probe/transducer position:
a. SX view/transverse view: Use the pisiform as a bony landmark for the SX/transverse view
of the carpal tunnel. Sweep the transducer proximal and distal to scan the structures as
they enter the wrist.
b. LX view/longitudinal view: Once you locate a structure of interest in the SX view, keeping
the structure in focus, rotate the probe 90 degrees to see the LX view of the structure of
interest (Figure 2-6).

A

B

C

Figure 2-6. Structures outside the
carpal tunnel. (A) Probe placement. (B)
SX view showing the FCR outside the
carpal tunnel in its own sheath, the
ulnar artery (white A) and ulnar nerve
outside the carpal tunnel, the median
nerve (MN) inside the carpal tunnel and
the palmaris longus (PL) outside the carpal tunnel as the most superficial structure. (C) LX view showing the palmaris
longus tendon (white arrows) as the most superficial thin band and the median nerve (MN) as a hypoechoic band. The
flexor tendons are a thicker hyperechoic band deeper to the median nerve.

3. Relevant anatomy: The FCR is on the radial side of the carpal tunnel in its own sheath and
runs distally through the groove on the medial side of the trapezium.8 The ulnar nerve and
artery are on the ulnar side next to the pisiform bone. The palmaris longus tendon continues
as the palmar aponeurosis in the palm and appears as a hyperechoic structure in the middle
just superficial to the flexor retinaculum in the volar aspect of wrist.
4. Points to remember: The palmaris longus may be absent in a small percentage of the population. There is an anomaly, reverse palmaris longus, that may be present in a very small percentage of the population where the muscle part of the palmaris longus is present at the level
of the volar wrist and the tendon is located proximally.6

Wrist and Hand

21

Volar-Radial Aspect of the Wrist
1. Patient position: Sitting or in supine with wrist in full supination and resting on the table
2. Probe/transducer position:
a. SX view/transverse view: Use the pisiform as a bony landmark for the SX/transverse view
of the carpal tunnel and then slide the probe on the radial aspect to view the FCR, which
lies outside the carpal tunnel in its own sheath.
b. LX view/longitudinal view: Once you locate the FCR in the SX view, keeping the FCR in
focus, rotate the probe 90 degrees to get the LX view of the FCR. In the same view, the
scaphotrapezial joint can be visualized (Figure 2-7).

A

B

C

Figure 2-7. FCR tendon. (A) Probe placement. (B) SX view of the FCR tendon on the radial side outside the carpal tunnel.
The median nerve is visible as a hypoechoic structure ulnar to the FCR. (C) LX view of the FCR tendon (white arrows),
which crosses the scaphotrapezial joint to insert on the anterior aspect of the base of the second metacarpal (MC).

22

Chapter 2

3. Relevant anatomy: The FCR inserts on the anterior aspect of the base of the second metacarpal
and gives small slips to the trapezial tuberosity and third metacarpal base (Figure 2-8).8

Figure 2-8. Relevant anatomy: The FCR inserts at the base of the second metacarpal and gives off tendinous slips to
the base of the third metacarpal and tuberosity of trapezium.

4. Points to remember: Severe cortical irregularities at the scaphotrapeziotrapezoid joint are suggestive of arthritic changes and are frequently associated with FCR tenosynovitis or rupture.8

Wrist and Hand

23

Volar-Ulnar Aspect of the Wrist
1. Patient position: Sitting or in supine with wrist in full supination and resting on the table
2. Probe/transducer position:
a. SX view/transverse view: Use the pisiform as a bony landmark for the SX/transverse view.
Move the probe slightly proximal to visualize the flexor carpi ulnaris (FCU) tendon.
b. LX view/longitudinal view: Using the pisiform as a bony landmark, keep the probe along
the FCU tendon, with the distal end of the probe on the pisiform (Figure 2-9).

A

B

C

Figure 2-9. FCU tendon. (A) Probe
placement. (B) SX view of the FCU
tendon (between the white arrows) and
median nerve (MN) radial to the FCU.
(C) LX view of the FCU tendon (white
arrows) attaching to the pisiform and its
distal tendinous slips to the hamate and
fifth metacarpal base (not shown).

For ulnar nerve imaging, locate the ulnar nerve in SX view and, keeping the nerve in focus,
rotate the probe 90 degrees to get the LX view of the ulnar nerve. The ulnar nerve is just radial
to the pisiform bone, followed by the ulnar artery, which is radial to the ulnar nerve (see
Figures 2-2 and 2-4).

24

Chapter 2

3. Relevant anatomy: The FCU is the ulnar-most tendon in the volar wrist and inserts into the
pisiform bone and via ligaments to the hamate and fifth metacarpal base (Figure 2-10).

Figure 2-10. Relevant anatomy: The FCU inserts into the pisiform and via ligaments to the hamate and fifth metacarpal
base.

4. Points to remember: FCU tenosynovitis may be considered as a differential diagnosis in ulnarsided wrist pain. For patients presenting with ulnar nerve symptoms, evaluate this area for any
space-occupying lesions like ganglion cysts, synovial masses, or soft tissue growths.

Wrist and Hand

25

DORSAL WRIST
Six Dorsal Compartments
(Tendons From Radial to Ulnar Aspect)
Anatomy of the region is shown in Figure 2-11.

Figure 2-11. The 6 dorsal compartments starting from the radial aspect: (1) abductor pollicis longus (APL) and extensor
pollicis brevis (EPB); (2) extensor carpi radialis longus (ECRL) and extensor carpi radialis brevis (ECRB); (3) extensor
pollicis longus (EPL); (4) extensor digitorum communis (EDC) and extensor indicis proprius (EIP); (5) extensor digiti
minimi (EDM); (6) extensor carpi ulnaris (ECU).

1. Patient position: Sitting or in supine with wrist in full pronation and resting on the table
2. Probe/transducer position: The wrist has 6 dorsal compartments of tendons (see Figure 2-11).
The first dorsal compartment tendons are the most radial tendons of the wrist. Starting from
radial to ulnar, the 6 dorsal compartment tendons can be scanned. The SX view is the best
view to locate the tendon of interest, and then the transducer can be rotated 90 degrees to get
the longitudinal view of each tendon.
a. SX view/transverse view: All the tendons of the 6 dorsal compartments can be scanned in
the SX view. It is important to align the transducer in the SX to the tendon and not to the
wrist to get the best view of the tendon. Remember that each tendon has a slightly oblique
course, and it is important to align the transducer perpendicular to the tendon to get the
best visualization.
b. LX view/longitudinal view: Once the tendon is located in the SX view, the transducer can
be rotated 90 degrees to get the LX view of each tendon.

26

Chapter 2

3. Relevant anatomy: The wrist has 6 dorsal compartments:
a. The first dorsal compartment consists of the abductor pollicis longus and extensor pollicis brevis. In a small part of the population, both tendons are separated by a septum.
Knowledge of the presence and absence of a septum is important if local steroid injection is
indicated in De Quervain’s tenosynovitis. In the presence of a septum, the involved tendon
can be selectively injected to maximize the benefit of the injection (Figure 2-12).9

A

B

C

Figure 2-12. First dorsal compartment. (A) Probe placement. Note that the transducer is in the SX to the tendons of the
first dorsal compartment, which is not a true SX view of the wrist. (B) Ultrasound image of the first dorsal compartment
tendons. The extensor pollicis brevis (white arrow) is dorsal to the abductor pollicis longus (white triangle). (C) Relevant
anatomy of the first dorsal compartment, which is the radial-most compartment of the 6 dorsal compartments of the
wrist, with the transducer position.

Wrist and Hand

27

b. The second dorsal compartment consists of the extensor carpi radialis longus and extensor
carpi radialis brevis. This compartment has the fewest anatomical anomalies (Figure 2-13).
A

B

C
Figure
2-13.
Second
dorsal
compartment. (A) Probe placement.
(B) Ultrasound image of the second
dorsal compartment tendons: extensor
carpi radialis brevis (white triangle) and
extensor carpi radialis longus (white
arrow). (C) Relevant anatomy of the
second dorsal compartment, with
transducer position.

c. The third dorsal compartment has a single tendon: the extensor pollicis longus. Lister’s
tubercle is an important bony landmark to differentiate the third dorsal compartment from
the second. The appearance of Lister’s tubercle can vary. It may appear as a sharp protuberance or a flatter protuberance (Figure 2-14).
A

B

C

Figure 2-14. Third dorsal compartment.
(A) Probe placement. (B) Ultrasound
image of the third dorsal compartment
tendons: extensor pollicis longus (big
white arrow); Lister’s tubercle (small
white arrow), an important bony
landmark that helps in differentiating the third dorsal compartment from the second dorsal compartment; and the
extensor carpi radialis brevis (ECRB) and extensor carpi radialis longus (ECRL). (C) Relevant anatomy of the third dorsal
compartment, with the transducer position.

28

Chapter 2
d. The fourth dorsal compartment has 5 tendon slips, including 4 slips of the extensor digitorum communis and 1 slip of the extensor indicis proprius. The fourth dorsal compartment
is located in the center of the wrist dorsum and is the only compartment with 5 tendons
(Figure 2-15).

A

B

C

Figure 2-15. Fourth dorsal compartment.
(A) Probe placement. (B) Ultrasound
image of the fourth dorsal compartment
(big white arrow) showing the extensor
pollicis longus tendon (small white
arrow) radial to the fourth dorsal
compartment. (C) Relevant anatomy of
the fourth dorsal compartment, with
the transducer position.

e. The fifth dorsal compartment has a single tendon: the extensor digiti minimi. The extensor
digiti minimi overlies the distal radioulnar joint (Figure 2-16).
A

B

C

Figure 2-16. Fifth dorsal compartment.
(A) Probe placement. (B) Ultrasound
image of the fifth dorsal compartment
(DC) showing the extensor digiti
minimi tendon (white arrow). Note that
the extensor digiti minimi overlies the
distal radioulnar joint. (C) Relevant anatomy of the fifth dorsal compartment, with the transducer position.

Wrist and Hand

29

f. The sixth dorsal compartment has a single tendon, the extensor carpi ulnaris (ECU), which
can be seen sitting in the bony groove of the distal ulna (Figure 2-17).10
A

B

C
Figure 2-17. Sixth dorsal compartment.
(A) Probe placement. (B) Ultrasound
image of the sixth dorsal compartment
showing the ECU (white arrow) sitting
in the groove of the distal end of the
ulna. (C) Relevant anatomy of the
sixth dorsal compartment, with the
transducer position.

4. Points to remember: Dorsal compartment tendons are best visualized at the level of the distal radius and ulna. In Figure 2-2A, notice the radius and ulna underneath the tendons. If
scanned distally at the level of the carpal bones or metacarpals, the aforementioned arrangement of tendons is not present, as they cross over to travel in different directions to their
respective attachment sites distally.

30

Chapter 2

DISTAL RADIOULNAR JOINT
1. Patient position: Sitting or in supine with wrist in full pronation and resting on the table
2. Probe/transducer position:
a. SX view/transverse view: Place the transducer over the dorsum of the distal end of radius
and ulna to bridging both bones.
b. LX view/longitudinal view: Once you have located the joint in the SX view, turn the probe
90 degrees to evaluate the joint in the LX view (Figure 2-18).

A

B

C

Figure 2-18. Distal radioulnar joint.
(A) Probe placement. (B) Ultrasound
image of the distal radioulnar joint
(white arrow); note that the extensor
digiti minimi (white triangle) overlies it.
Extensor digiti minimi appears dark in this image due to anisotropy. (C) Relevant anatomy and transducer position for
imaging the distal radioulnar joint.

3. Relevant anatomy: The triangular fibrocartilage complex (TFCC) is the major stabilizer of
the distal radioulnar joint. The fifth dorsal compartment tendon, the extensor digiti minimi,
directly overlies the distal radioulnar joint. On the volar aspect, the pronator quadratus
muscle fibers are oriented transversely.11
4. Points to remember: The distal radioulnar joint is commonly involved in rheumatoid arthritis and can cause secondary pathological changes in the extensor digiti minimi tendon that
overlies it.

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31

SCAPHOLUNATE LIGAMENT
Anatomy of the region is shown in Figure 2-19.

Figure 2-19. Relevant anatomy of the scapholunate ligament.

1. Patient position: Sitting with wrist in full pronation, slight flexion for dorsal band, and supination with slight extension for volar band12

32

Chapter 2

2. Probe/transducer position:
a. SX view/transverse view: Locate Lister’s tubercle in the SX view and then move the probe
distally to get the scapholunate joint view to visualize the interval. The dorsal band of the
scapholunate ligament appears as a hyperechoic triangular structure with an average thickness of 1.1 mm and average length of 4.2 mm.13 The SX view is the best view to evaluate
this region (Figure 2-20).12

A

B

Figure 2-20. Dorsal band of the scapholunate ligament. (A) Probe placement. Wrist in full pronation and slight
flexion. Locate Lister’s tubercle in the SX view and then move the probe distally to get the scapholunate joint view to
visualize the dorsal band. (B) Ultrasound image of the dorsal band of the scapholunate ligament, which appears as a
hyperechoic fibrillar structure (white arrow).

Volar band of the scapholunate ligament: Bridge the scapholunate interval on the volar
aspect to visualize the anterior band as a hyperechoic fibrillar structure (Figure 2-21).12

A

B

Figure 2-21. Volar band of the scapholunate ligament. (A) Probe placement. Wrist in supination with slight extension.
Bridge the scapholunate interval on the volar aspect to visualize the volar band as a hyperechoic fibrillar structure. (B)
Ultrasound image of the volar band of the scapholunate ligament, which appears as a hyperechoic fibrillar structure
(white arrow).

b. LX view/longitudinal view: Once the scapholunate joint is located in the SX view, rotate the
probe to evaluate the joint in the LX view if needed.

Wrist and Hand

33

3. Relevant anatomy: Lister’s tubercle is an important bony landmark to navigate to the scapholunate interval dorsally.
4. Points to remember: The scapholunate interval can be compared with the contralateral wrist to
measure the separation distance in cases of ligament tear. A scapholunate distance larger than
4.2 mm is an indication of a tear in the dorsal band of the scapholunate. Dynamic assessment
can be performed with radial/ulnar deviation or clenching of the fist.13

TRIANGULAR FIBROCARTILAGE COMPLEX
Anatomy of the region is shown in Figure 2-22.

Figure 2-22. TFCC anatomy.

34

Chapter 2

1. Patient and probe/transducer position:
a. Dorsal view: Patient seated with the hand in full pronation and resting on the table. Ask
the patient to radially deviate the wrist to open up the ulnar aspect of the wrist. Place the
transducer in the LX view over the dorso-ulnar aspect of wrist joint, keeping the distal end
of the ulna and triquetrum bone in view. The TFCC is seen as a triangular region between
the ulnar and triquetrum through the acoustic window of the ECU tendon (Figure 2-23).

A

B

Figure 2-23. Dorsal view of the TFCC. (A) Probe placement. Wrist in full
pronation and resting on the table. Ask the patient to deviate the wrist radially
to open up the ulnar aspect of the wrist. Place the transducer in the LX view over the dorso-ulnar aspect of the wrist joint,
keeping the distal end of the ulna and triquetrum bone in view. (B) Ultrasound image of the dorsal view of the TFCC,
which is seen as a triangular region between the ulnar and triquetrum through the acoustic window of the ECU tendon.

b. Volar view: Hand resting on the table with full supination. Place the probe on the ulnar
aspect of the wrist in the LX to visualize the TFCC region from the anterior aspect
(Figure 2-24).

A

B

Figure 2-24. Volar view of the TFCC. (A) Probe placement. Hand resting on the
table with full supination. Place the probe on the ulnar aspect of the wrist in the
LX to visualize the TFCC region from the anterior aspect. (B) Ultrasound image
of the volar view of the TFCC (white arrow), which is seen as the triangular region between the ulna and triquetrum.

Wrist and Hand

35

c. Dorsal radioulnar ligament: Hand resting on the table in pronation. The probe is placed on
the dorsal aspect bridging the radius and ulna to visualize the hyperechoic dorsal radioulnar ligament (Figure 2-25).

A

B

Figure 2-25. Dorsal radioulnar ligament. (A) Probe placement. Hand resting
on the table in pronation. The probe is placed on the dorsal aspect bridging
the radius and ulna. (B) Ultrasound image of the dorsal radioulnar ligament
(white arrow) as a hyperechoic fibrillar structure.

d. Volar radioulnar ligament and limited disk view: Wrist in supination and slight extension.
The probe is placed on the volar aspect bridging the radius and ulna to visualize the volar
radioulnar ligament as a hyperechoic structure (Figure 2-26).12

A

B

Figure 2-26. Volar radioulnar ligament. (A) Probe placement. Wrist in supination
and slight extension. The probe is placed on the volar aspect bridging the radius
and ulna. (B) Ultrasound image of the volar radioulnar ligament (white arrow)
as a hyperechoic fibrillar structure. Deep to the volar radioulnar ligament, a
limited view of the disk as a triangular structure can be seen.

36

Chapter 2

2. Relevant anatomy: The TFCC comprises the dorsal and volar radioulnar ligaments, central
articular disk, meniscus homologue, ulnar collateral ligament (UCL), subsheath of the fifth
and sixth dorsal compartments, proximal portion of the ulnolunate, and ulnotriquetral ligaments.14 It cannot be evaluated in full detail with the ultrasound imaging and requires magnetic resonance imaging or arthroscopic assessment. Only the periphery of the TFCC can be
visualized with ultrasound.
3. Points to remember: Patients with a TFCC tear present with ulnar-sided pain, instability, clicking, and difficulty with activities like turning a doorknob. Radial and ulnar deviation of the
wrist are often painful.

HAND AND DIGITS
Volar Aspect
Anatomy of the region is shown in Figures 2-27 and 2-28.

Figure 2-27. Flexor tendons of the digit and the flexor tendon sheath. On the volar aspect of the digit, the flexor
tendons (flexor digitorum profundus [FDP] and FDS) are surrounded by a synovial layer (blue) and contained within
the flexor tendon sheath (purple), which is further divided into areas of annular (A1-A5) and cruciate (C1-C3) pulleys.
The metacarpophalangeal (MCP), proximal interphalangeal (PIP), and distal interphalangeal joints on the volar aspect
are covered by volar plates (orange), which also provide insertion to the flexor tendon sheath on either side. The flexor
tendon sheath provides stability to the flexor tendons by holding it close to the bone and joint as the finger moves into
flexion and extension. (DP = distal phalanx; MC = metacarpal; MP = middle phalanx; PP = proximal phalanx.)

Wrist and Hand

37

Figure 2-28. Volar aspect of the digit in a transverse section at the level of proximal phalanx showing 2 tendon slips of
the FDS and 1 tendon slip of the FDP surrounded by the synovial layer (pink) and contained within the flexor tendon
sheath (blue). On either side of the tendon are digital nerves and blood vessel bundles.

1. Patient position: Sitting with wrist in full supination and resting on the table
2. Probe/transducer position:
a. LX view/longitudinal view: The transducer is placed in LX alignment with respect to the
digit of interest. The digit is scanned proximal to distal to evaluate the structures in continuity (Figure 2-29).

A

B

Figure 2-29. (A) Ultrasound image of the LX view of the digit. (B) Labelled image of the LX view of the digit showing
the flexor tendons (FDS and FDP), annular (A1-A5) and cruciate (C1-C3) pulleys, and interphalangeal joints (distal
interphalangeal [DIP] joint, MCP joint, and PIP joint).

38

Chapter 2
b. SX view/transverse view: The transducer is placed in SX alignment with respect to the
digit of interest. The digit is scanned from proximal to distal to evaluate the structures in
continuity (Figure 2-30).

A

B

Figure 2-30. (A) Ultrasound image of the SX view of the digit at the level of the proximal phalanx. (B) Labelled image of
the SX view of the digit showing the FDS tendons overlying a single FDP tendon contained within the pulley or flexor
tendon sheath (blue), with the digital artery (white A) and digital nerve (N) on either side.

3. Relevant anatomy: It is important to understand the anatomy of the digits. Figure 2-27 shows
the FDP and FDS of the digit covered by the synovial layer, which helps in the gliding of the
tendon. The flexor tendon sheath is a tunnel-like structure attaching on the margins of the
phalangeal bones and palmar ligaments, starting from the head of the metacarpal to the distal
phalangeal joint level. The flexor tendon sheath is divided into regions of annular and cruciate
pulleys depending on the fiber orientation of the sheath. It is important to note that the flexor
tendon sheath forms a tunnel with denser areas at the annular pulley, oblique fiber arrangement at the cruciate part of the pulley, and in between the loose, thin part of the sheath where
synovial outpouching may be seen.15,16
4. Points to remember: At the level of the metacarpal head, the FDP is deep to the FDS. At the
level of the proximal phalanx, the FDS splits and is seen as 2 superficial slips on either side of
the FDP. The FDS then attaches to the middle phalanx, and the FDP emerges superficial to
travel distally to attach to the distal phalanx.

Wrist and Hand

Dorsal Aspect
Anatomy of the region is shown in Figure 2-31.

Figure 2-31. Anatomy of the dorsal aspect of the digit. (MCPJ = metacarpophalangeal joint.)

39

40

Chapter 2

1. Patient position: Sitting with wrist in full pronation and hand resting on the table
2. Probe/transducer position:
a. LX view/longitudinal view: The transducer is aligned along the extensor tendon, which is
then followed proximal to distal. The most distal structure seen is the nail bed and nail
(Figure 2-32).

Figure 2-32. Ultrasound image of the dorsal aspect of the digit. The extensor tendon (white arrows) is much thinner
than the flexor tendons on the volar aspect of the digit. (DIP = distal interphalangeal joint)

b. SX view/transverse view: The SX view is used only after the extensor tendons are visualized
in the LX view to confirm the findings.
3. Relevant anatomy: The extensor tendons are much thinner than the flexor tendons of the
digits. Dynamic examination is important when the integrity of the extensor tendon is in
question. The nail appears hyperechoic on ultrasound with a hypoechoic nail bed.
4. Points to remember: The skin crease over the MCP and interphalangeal joints causes refraction and attenuation of the ultrasound beam, which results in poor visibility of the tendons
or other structures of interest in this region. Flexing the digits adds a stretch to the loose skin
and is a useful technique to avoid the artifacts created by the skin crease.

Wrist and Hand

41

Collateral Ligaments of Proximal Interphalangeal Joint
1. Probe position:
a. LX view: The transducer is placed on the ulnar/radial aspect of the proximal interphalangeal (PIP) joint of the digit (Figure 2-33).

A

B

C

Figure 2-33. Collateral ligament of the PIP joint of digits. (A) Relevant anatomy of the collateral ligament of the PIP
joint. The collateral ligament is divided into 2 parts: proper ligament (green) and accessory ligament (blue). The
proper collateral ligament arises from the head of proximal phalanx (PP) and attaches to the middle phalanx (MP). The
accessory ligament is the smaller part of the collateral ligament and attaches to the volar plate. (B) Probe placement.
The transducer is placed on the ulnar/radial aspect of the PIP joint of the digit. (C) Ultrasound image of the collateral
ligament (white arrows) as a hyperechoic fibrillar structure.

2. Relevant anatomy: The collateral ligament of the PIP joint is divided into 2 parts: proper
ligament and accessory ligament. The proper collateral ligament arises from the head of the
proximal phalanx and attaches to the middle phalanx. The accessory ligament is the smaller
part of the collateral ligament and attaches to the volar plate.17
3. Points to remember: A thickened collateral ligament may be observed in cases of finger sprain.

42

Chapter 2

Ulnar and Radial Collateral Ligaments of
First Metacarpophalangeal Joint
1. Patient and probe/transducer position:
a. For the UCL: Wrist in mid-supination/pronation with thumb abduction. The transducer is
placed in the LX along the ulnar aspect of the first MCP joint in a slight oblique orientation
(Figure 2-34).

A

B

Figure 2-34. UCL of the first MCP joint.
(A) Probe placement. Wrist in midsupination/pronation with thumb in
abduction. The transducer is placed in
the LX along the ulnar aspect of first
MCP joint in slight oblique orientation.
(B) Ultrasound image of the UCL (white
arrows), which appears as a hyperechoic
fibrillar structure between the first
metacarpal and proximal phalanx. (C) C
Relevant anatomy: The adductor pollicis
aponeurosis overlies the UCL and has an oblique orientation relative to the UCL. UCL orientation is dorsal to palmar, and
adductor pollicis orientation is palmar to dorsal. (EPL = extensor pollicis longus tendon.)

Wrist and Hand

43

b. For the radial collateral ligament (RCL): Wrist supinated and resting on the table. The
transducer is placed in the LX along the radial aspect of the first MCP joint in a slight
oblique orientation (Figure 2-35).

A

B

Figure 2-35. RCL of the first MCP joint. (A) Probe placement: wrist supinated
and resting on the table. The transducer is placed in LX along the radial
aspect of the first MCP joint in slight oblique orientation. (B) Ultrasound
image of the RCL (white arrows), which appears as a hyperechoic fibrillar
structure between the first metacarpal and proximal phalanx.

2. Relevant anatomy: Both UCL and RCL are the primary stabilizers of the first MCP joint. The
RCL and UCL ligaments are divided into the larger proper ligament and smaller accessory
ligament. The proper ligament of the RCL and UCL originates from the dorsal aspect of the
first metacarpal head and inserts on the volar aspect of the base of the proximal phalanx.
The accessory ligament of the RCL and UCL attaches to the volar plate and sesamoid bones.
Proper collateral ligaments are taut during flexion, and accessory ligaments are taut during
extension.18
3. Points to remember: The adductor pollicis muscle overlies the UCL and has an oblique orientation relative to the UCL. UCL orientation is dorsal to palmar, and adductor pollicis orientation
is palmar to dorsal. In a Stener lesion, the adductor pollicis aponeurosis may be interposed
between the proximal phalanx and the proximally retracted UCL and thus interfere with ligament healing.18,19

44

Chapter 2

Hand Muscles and Associated Tendons
1. Patient position: Sitting or in supine with wrist in full supination and resting on the table
2. Probe/transducer position:
a. SX view/transverse view: The transducer is placed transversely across the palm to evaluate
the flexor tendons and lumbrical muscles in the hand (Figures 2-36 and 2-37).

A

B

C

Figure 2-36. SX view of the palm at the
level of the metacarpal shaft. (A) Probe
placement. (B) Ultrasound image of
the palm at the level of the metacarpal
shaft. (C) Labelled image showing
flexor tendons (FT), lumbrical muscles
(L), palmar interossei muscles (PI), and
metacarpal (MC).

A

B

C

Figure 2-37. SX view of the palm at the level of the metacarpal head-neck junction. (A) Probe placement. (B)
Ultrasound image of the palm at the level of the metacarpal head-neck junction. (C) Labelled image showing FDS,
FDP, and metacarpal (MC).

b. LX view/longitudinal view: The transducer can be rotated 90 degrees to visualize the structure of interest in the LX view.

Wrist and Hand

45

3. Relevant anatomy: In the hand, the flexor tendons are arranged with the FDP deeper to
the FDS, and the lumbrical muscles are on either side of the tendons, except the first digit,
which has a single flexor tendon (FPL) attaching to the distal phalanx. The FPL runs laterally
through the thenar muscles to the first digit (Figure 2-38).

A

B

Figure 2-38. Thenar eminence. (A) Probe
placement. (B) SX view of the thenar
eminence showing the FPL (white
arrow) surrounded by thenar muscles.
(MC = metacarpal.) (C) LX view of the
thenar eminence showing the FPL (white
arrow) with thenar muscles above and
below it. (MCPJ = metacarpophalangeal
joint.)

C

4. Points to remember: Tenosynovitis of the flexor tendons at the level of the palm and wrist
can be missed due to the presence of hypoechoic muscles in the near vicinity. Color ultrasound should be used to check for signs of vascularity, as can be seen in cases of synovitis or
tenosynovitis.

46

Chapter 2

Carpometacarpal Joints
1. Patient position: Sitting or in supine with wrist in mid-supination/pronation for the first carpometacarpal (CMC) joint and wrist in full pronation with palm side down for other CMC joints
2. Probe/transducer position:
a. LX view/longitudinal view: The transducer is placed in the LX along the carpal and metacarpal bones of the CMC joint of interest (Figures 2-39 and 2-40).

A

B

Figure 2-39. First CMC joint. (A) Probe placement. (B) Ultrasound image of the
first CMC joint. (CMCJ = carpometacarpal joint; MC = metacarpal.) (C) Relevant
anatomy.

C

Wrist and Hand
A

47

B

Figure 2-40. Third CMC joint. (A) Probe placement. (B) Ultrasound image of the
third CMC joint. (CMCJ = carpometacarpal joint; MC = metacarpal.) (C) Relevant
anatomy.

C

b. SX view/transverse view: The transducer is placed transversely across the CMC joint if
needed.
3. Relevant anatomy: For the imaging of the first CMC joint, it is important to visualize 4 bony
structures—the distal end of the radius, the scaphoid, the trapezium, and the proximal end
of the first metacarpal—and then focus on the area of interest, which is first CMC joint. This
approach ensures that other pathologies of the region are not missed. For the second through
third CMC joints, the transducer is aligned with the proximal end of the metacarpal.
4. Points to remember: First CMC joint arthritis is common. Ultrasound is a great tool to detect
early bony changes or synovitis, which is often missed in early radiographs.
Carpal boss, which is a bony protuberance of the second or third CMC joint, may presents
as a bump on the dorsum of the hand. Sometimes it is associated with the bursa or cystic mass
that covers the bony protuberance.

48

Chapter 2

REFERENCES
1.
2.
3.
4.

5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
17.
18.
19.

Georgiev GP, Karabinov V, Kotov G, Iliev A. Medical ultrasound in the evaluation of the carpal tunnel: a critical
review. Cureus. 2018;10(10):e3487.
Park GY, Kwon DR, Seok JI, Park DS, Cho HK. Usefulness of ultrasound assessment of median nerve mobility
in carpal tunnel syndrome. Acta Radiol. 2018;59(12):1494-1499.
Cartwright MS, Walker FO. Neuromuscular ultrasound in common entrapment neuropathies. Muscle Nerve.
2013;48(5):696-704.
van Doesburg MH, Mink van der Molen A, Henderson J, Cha SS, An KN, Amadio PC. Sonographic measurements of subsynovial connective tissue thickness in patients with carpal tunnel syndrome. J Ultrasound Med.
2012;31(1):31-36.
Werthel JD, Zhao C, An KN, Amadio PC. Carpal tunnel syndrome pathophysiology: role of subsynovial connective tissue. J Wrist Surg. 2014;3(4):220-226.
Chammas M, Boretto J, Burmann LM, Ramos RM, Dos Santos Neto FC, Silva JB. Carpal tunnel syndrome – part
I (anatomy, physiology, etiology and diagnosis). Rev Bras Ortop. 2014;49(5):429-436.
Miyamoto H, Siedentopf C, Kastlunger M, et al. Intracarpal tunnel contents: evaluation of the effects of corticosteroid injection with sonoelastography. Radiology. 2014;270(3):809-815.
Bishop AT, Gabel G, Carmichael SW. Flexor carpi radialis tendinitis. Part I: operative anatomy. J Bone Joint Surg
Am. 1994;76(7):1009-1014.
Mahakkanukrauh P, Mahakkanukrauh C. Incidence of a septum in the first dorsal compartment and its effects
on therapy of de Quervain’s disease. Clin Anat. 2000;13(3):195-198.
Plotkin B, Sampath SC, Sampath SC, Motamedi K. MR imaging and US of the wrist tendons. Radiographics.
2016;36(6):1688-1700.
Haugstvedt JR, Langer MF, Berger RA. Distal radioulnar joint: functional anatomy, including pathomechanics.
J Hand Surg Eur Vol. 2017;42(4):338-345.
Taljanovic MS, Goldberg MR, Sheppard JE, Rogers LF. US of the intrinsic and extrinsic wrist ligaments and
triangular fibrocartilage complex—normal anatomy and imaging technique. Radiographics. 2011;31(1):E44.
Meyer P, Lintingre PF, Pesquer L, Poussange N, Silvestre A, Dallaudiere B. Imaging of wrist injuries: a standardized US examination in daily practice. J Belg Soc Radiol. 2018;102(1):9.
Mathoulin C. Anatomy of the triangular fibrocartilage complex: current concepts. In: Mathoulin C, ed. Wrist
Arthroscopy Techniques. Stuttgart, Germany: Thieme; 2015.
Jones MM, Amis AA. The fibrous flexor sheaths of the fingers. J Anat. 1988;156:185-196.
Doyle JR. Anatomy of the finger flexor tendon sheath and pulley system. J Hand Surg. 1988;13(4):473-484.
Allison DM. Anatomy of the collateral ligaments of the proximal interphalangeal joint. J Hand Surg.
2005;30(5):1026-1031.
Rawat U, Pierce JL, Evans S, Chhabra AB, Nacey NC. High-resolution MR imaging and US anatomy of the
thumb. Radiographics. 2016;36(6):1701-1716.
Ebrahim FS, Jager T, Marcelis S, Jamadar DA, Jacobson JA. US diagnosis of UCL tears of the thumb and Stener
lesions: technique, pattern-based approach, and differential diagnosis. Radiographics. 2006;26(4):1007-1020.

3
Elbow
Mohini Rawat, DPT, MS, ECS, OCS, RMSK

Contents
• Anterior Elbow
º Joint Anatomy
º Distal Biceps Tendon
º Brachialis
º Pronator Teres
• Medial Elbow
º Common Flexor Tendon
º Ulnar Nerve
º Ulnar Collateral Ligament
• Lateral Elbow
º Common Extensor Tendon
º Lateral Collateral Ligament Complex
º Radial Nerve
• Posterior Elbow
º Joint Anatomy
º Triceps Tendon
º Olecranon Bursa

- 49 -

Rawat M.
Atlas of Musculoskeletal Ultrasound of the Extremities (pp 49-79).
© 2021 SLACK Incorporated.

50

Chapter 3

ANTERIOR ELBOW
Joint Anatomy
1. Patient position: Sitting with elbow resting on the table with full supination and extension
2. Probe/transducer position: The probe is placed transversely on the anterior aspect of the
elbow to visualize the joint in the short axis (SX) view. The probe is then rotated 90 degrees
to visualize the anteromedial and anterolateral aspect of the joint in the long axis (LX) view
(Figures 3-1 through 3-4).

A

B

C

Figure 3-1. SX view of the anterior elbow. (A) Probe placement. (B) Ultrasound
image of the anterior elbow in the SX view. A hyperechoic bony interface
is lined by an anechoic cartilage interface. The distal biceps tendon (white
arrow) is hyperechoic and the most superficial tendon. (C) Relevant anatomy
and probe placement.

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51

Figure 3-2. Expanded SX view of the anterior elbow showing soft tissue structures. The radial nerve (yellow arrow)
is between the brachialis and brachioradialis muscles. The median nerve (white arrow) is between the brachialis and
pronator teres muscles.

A

C

B

Figure 3-3. Anterolateral LX view of the elbow. (A) Probe placement. (B)
Ultrasound image of the anterolateral elbow in the LX view, showing the
radial fossa (white arrow), joint (white triangle), and radial head and neck. (C)
Relevant anatomy and probe placement.

52
A

Chapter 3
B

C
Figure 3-4. Anteromedial LX view of the elbow. (A) Probe placement. (B)
Ultrasound image of the anteromedial elbow in the LX view, showing the
coronoid fossa (white arrow), joint (white triangle), coronoid process (CP), and
trochlea of the humerus. (C) Relevant anatomy and probe placement.

3. Relevant anatomy: The distal humerus is seen as a hyperechoic bony interface lined by
anechoic cartilage above the bony surface. The convex surface is the capitellum, and the concave surface is the trochlea, which is divided into lateral and medial facets.1 Overlying the
joint surface is the brachialis muscle belly. On the radial side, the brachioradialis muscle can
be seen. Between the brachialis and brachioradialis is the radial nerve. On the ulnar side, the
pronator teres muscle is seen. Between the brachialis and pronator teres, the median nerve is
seen next to the brachial artery.
4. Points to remember: Cartilage is best visualized with full extension of the elbow. Adding flexion may limit visualization of the cartilage-lined surface of the distal humerus.

Elbow

53

Distal Biceps Tendon
Relevant anatomy of the distal biceps tendon (DBT) is shown in Figure 3-5.

Figure 3-5. Relevant anatomy of the DBT, which twists from predominantly the frontal plane to the sagittal plane
before inserting on the radial tuberosity. As the DBT crosses the elbow joint, a thin fibrous structure, the lacertus
fibrosus or bicipital aponeurosis (green), fans out in the ulnar direction and merges with the superficial fascia to span
the flexor muscle compartment of the forearm.

54

Chapter 3

1. Patient position: Sitting with full supination and slight elbow flexion
2. Probe/transducer position:
a. SX view: The probe is placed transversely on the anterior aspect of the elbow to visualize
the DBT (Figure 3-6).

A

B

Figure 3-6. SX view of the DBT, anterior approach. (A) Probe placement. (B) SX
view of the DBT (white arrow).

b. LX view:
i. Anterior approach: The probe is rotated 90 degrees from the SX view to visualize the
DBT in the LX view, and the tendon is followed distally to its insertion site at the radial
tuberosity. In the distal part, passive supination of the forearm and increased pressure
on the distal part of the probe are needed to visualize the distal insertional fibers of the
DBT (Figure 3-7).1,2

A

B

Figure 3-7. LX view of the DBT, anterior approach. (A) Probe placement. (B) LX view of
the DBT (white arrows). (RH = radial head.)

Elbow

55

ii. Lateral approach: The probe is placed on the lateral aspect of the elbow with the elbow
flexed to 90 degrees and the forearm supinated to visualize the DBT in the LX view
through the acoustic window of the muscle mass of the forearm extensors, brachioradialis, and supinator muscle (Figure 3-8).1,3

A

B

Figure 3-8. LX view of the DBT, lateral approach. (A) Probe placement:
probe (red rectangle), DBT (blue arrow), radius (yellow rectangle), ulna (black
rectangle). (B) With the elbow flexed to 90 degrees and the forearm supinated, the DBT (white arrows) is visualized
in the LX view through the acoustic window of the muscle mass of the forearm extensors (E), brachioradialis, and
supinator muscle (S).

56

Chapter 3
iii. Medial approach: With the elbow flexed to 90 degrees and the forearm supinated, the
probe is placed in the LX on the medial aspect to visualize the DBT through the acoustic
window of the flexor-pronator mass. The brachial artery is medial to the DBT and helps
enhance echogenicity of the DBT with this approach (Figure 3-9).1,4

A

Figure 3-9. LX view of the DBT, medial
approach. (A) Probe placement. (B) LX
view of the DBT (white arrows) showing
the brachial artery (white triangle). With
the elbow flexed to 90 degrees and
the forearm supinated, the probe is
placed in the LX on the medial aspect to
visualize the DBT through the acoustic
window of the flexor-pronator mass.
The brachial artery is medial to the DBT.

B

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57

iv. Posterior approach: This is a limited view of the distal portion of the DBT fibers. The
elbow is maximally flexed and resting on the table with the forearm in full pronation
and the wrist flexed. The probe is placed transversely between the radius and ulna at
the level of the radial tuberosity, about 4 cm distal to the olecranon process. A dynamic
maneuver of supination and pronation will show the DBT with pronation and cause it
to disappear upon supination (Figure 3-10).1

A

B

C

Figure 3-10. LX view of the DBT,
posterior approach. (A) Probe
placement. (B) The DBT (white arrow)
between the radius and ulna. The
elbow is maximally flexed and resting
on the table with the forearm in full
pronation and the wrist flexed. The probe is placed transversely between the radius and ulna at the level of the radial
tuberosity, about 4 cm distal to the olecranon process. (C) Relevant anatomy and probe placement.

3. Relevant anatomy: The DBT twists from predominantly the frontal plane to the sagittal plane
before inserting on the radial tuberosity. As the DBT crosses the elbow joint, a thin, fibrous
structure called lacertus fibrosus, or bicipital aponeurosis, fans out in the ulnar direction and
merges with the superficial fascia to span the flexor muscle compartment of the forearm.5
The footprint of the DBT on the radial tuberosity is divided into 2 parts: a larger proximal
footprint for the long head of the biceps fibers and a small, thin distal footprint for the short
head of the biceps fibers.5 The DBT is surrounded by bicipitoradial bursa, which in normal
states is not depicted on ultrasound.
4. Points to remember: Because of the 90-degree twist in the DBT fibers from the frontal plane
to the sagittal plane and the sudden change in the course of the tendon from being the most
superficial tendon at the level of the elbow joint to the most posterior as it inserts on the medial
aspect of radius, scanning the tendon in the LX view can be challenging. Knowledge of fiber
orientation and course of the tendon is helpful in proper visualization of the tendon. Full supination and increased pressure on the distal end of the probe to make the probe parallel to the
tendon is important to counter the refraction artifact due to the oblique direction of the fibers.

58

Chapter 3

Brachialis
1. Patient position: Sitting with elbow extension and resting on the table
2. Probe/transducer position: The probe is placed transversely on the anterior aspect of the elbow
to visualize the brachialis in the SX view, and then the probe is moved distally in the SX view
to visualize the distal portion of the brachialis. The probe is rotated 90 degrees to scan the
brachialis muscle tendon complex in the LX view as it attaches on the coronoid process of the
ulna (Figures 3-11 and 3-12).

A

Figure 3-11. SX view of the brachialis.
(A) Probe placement. (B) SX view of
the brachialis muscle (white arrow) at
the proximal level. (C) SX view of the
brachialis muscle tendon (white arrow)
at the distal muscle tendon level.

B

C

Elbow
A

59

B

Figure 3-12. LX view of the brachialis.
(A) Probe placement. (B) LX view
showing the superficial head (SH)
and deep head (DH) of the brachialis
attaching to the coronoid process.

3. Relevant anatomy: The brachialis is divided into 2 parts: The larger superficial head originates
from the anterolateral aspect of the middle third of the humerus and lateral intermuscular
septum, and the deep head originates from the distal third of the anterior aspect of the humerus and the medial intermuscular septum. The brachialis continues distally and inserts on the
coronoid process of the ulna. The superficial head attaches more distally than the deep head.6
4. Points to remember: The tendon of the distal brachialis is thinner than the DBT. Variations of
the distal insertion of the brachialis tendon on the coronoid process of the ulna include purely
muscular, tendinous, or mixed.1

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Chapter 3

Pronator Teres
Relevant anatomy of the region is shown in Figure 3-13.

Figure 3-13. Relevant anatomy of the pronator teres, which has 2 heads: the humeral head and ulnar head. The 2 heads
fuse to form a muscle belly, which inserts through a short tendon on the lateral aspect of the middle third of the radius.
The median nerve runs between the ulnar and humeral heads of the pronator teres. The ulnar artery runs deep to the
ulnar head of the pronator teres.

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61

1. Patient position: Sitting with elbow extension and forearm full supination
2. Probe/transducer position: The probe is placed transversely over the pronator teres at the level
of distal humerus and then moved distally along the muscle belly to scan the humeral and
ulnar heads as they course distally toward the lateral aspect of the radius. The probe is then
rotated 90 degrees to scan the pronator teres in the LX view and as it inserts over the lateral
aspect of the radius (Figures 3-14 through 3-16).

A

B

Figure 3-14. SX view of the pronator
teres at the level of the humeral head.
(A) Probe placement. (B) SX view of
the humeral head of the pronator teres
(white star) medial to the brachialis
muscle.

A

Figure 3-15. SX view of the pronator
teres at the level of the ulnar head. (A)
Probe placement. (B) SX view of the
pronator teres at the ulnar head level.
Shown are the pronator teres humeral
head (white star), pronator teres ulnar
head (white arrow), and median nerve
(white triangle), which is between the
humeral head and ulnar head of the
pronator teres.

B

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A

C

Chapter 3
B

Figure 3-16. LX view of the pronator teres at the distal insertion. (A) Probe
placement. (B) LX view of the distal insertion of the pronator teres tendon
(white arrows) on the lateral aspect of the middle third of the radius. (C)
Relevant anatomy and probe placement.

3. Relevant anatomy: The pronator teres has 2 heads: humeral and ulnar. The humeral head
originates from the proximal and anterior aspect of the medial epicondyle, medial intermuscular septum of the arm, medial common flexor tendon, and antebrachial fascia. The ulnar
head originates from the medial border of the coronoid process and the medial aspect of the
brachialis tendon. The 2 heads fuse to form a muscle belly, which inserts through a short tendon on the lateral aspect of the middle third of the radius.7
4. Points to remember: A dynamic maneuver where the elbow is flexed and the patient is asked
to pronate against resistance and then the examiner extends the forearm while the patient
maintains resisted pronation can facilitate detection of focal median nerve compression.7

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MEDIAL ELBOW
Common Flexor Tendon
1. Patient position: Sitting with elbow slightly flexed and externally rotated
2. Probe/transducer position: The probe is placed on the medial epicondyle as a bony landmark
and oriented along the common flexor tendon. The tendon is shorter than the common extensor tendon. The SX view is obtained by rotating the probe 90 degrees from the LX orientation
(Figures 3-17 and 3-18).8

A

B

C
Figure 3-17. LX view of the common flexor origin. (A) Probe placement showing the location of the medial epicondyle
(blue star). (B) LX view of the pronator teres humeral head (white arrow), which originates from the proximal and anterior
aspect of the medial epicondyle. (C) LX view of the common flexor origin (white arrow) at the medial epicondyle.

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Chapter 3

A

B

Figure 3-18. SX view of the common
flexor tendon. (A) Probe placement. (B)
SX view of the common flexor tendon
(white arrow) at the medial epicondyle.

3. Relevant anatomy: Common flexor-pronator muscles originate from the medial epicondyle.
4. Points to remember: Deep to the common flexor-pronator origin, the anterior band of the
ulnar collateral ligament (UCL) can be visualized.

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65

Ulnar Nerve
1. Patient position: Supine with elbow flexed and arm externally rotated
2. Probe/transducer position: The probe is placed over the medial elbow bridging the medial epicondyle and olecranon process to visualize the ulnar nerve in the SX view. The probe is then
rotated 90 degrees to visualize the nerve in the LX view (Figures 3-19 and 3-20).

A

B

C

D

Figure 3-19. SX view of the ulnar nerve. (A) Probe placement showing the location of the medial epicondyle (blue star).
(B) Ulnar nerve at the level proximal to the medial epicondyle. The ulnar nerve (white arrow) is seen above the triceps
muscle. (C) Ulnar nerve (white arrow) at the level of the medial epicondyle (ME) between the medial epicondyle and
the olecranon (OL). (D) Ulnar nerve (white arrow) between the 2 heads of the flexor carpi ulnaris (FCU).

66
A

Chapter 3
B

C

D

Figure 3-20. LX view of the ulnar nerve. (A) Probe placement. (B) Ulnar nerve (small white arrow) proximal to the
medial epicondyle. (C) Ulnar nerve (white arrow) at the medial epicondyle. (D) Ulnar nerve (white arrow) distal to the
medial epicondyle between the 2 heads of the flexor carpi ulnaris muscle.

3. Relevant anatomy: The ulnar nerve is retroepicondylar before it enters the cubital tunnel and
then emerges anteriorly after passing through the 2 heads of the flexor carpi ulnaris. The cubital tunnel is a fibro-osseous tunnel, the roof of which is formed by Osborne’s fascia connecting
the medial epicondyle and olecranon process.8
4. Points to remember: Scanning the ulnar nerve around the elbow requires knowledge of the
course of the nerve around the epicondyle, which necessitates slight rotation of the probe as
the nerve is followed from distal to proximal or vice versa.

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67

Ulnar Collateral Ligament
Relevant anatomy of the region is shown in Figure 3-21.

Figure 3-21. Anatomy of the UCL of the elbow. There are 3 bands: anterior, posterior, and transverse or oblique bundle.

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Chapter 3

1. Patient position: Sitting with elbow slightly flexed and externally rotated
2. Probe/transducer position: The probe is placed on the medial epicondyle as the bony landmark
and oriented along the common flexor tendon. Deep to the common flexor tendon anterior
band, the UCL is visualized as a hyperechoic fibrillary structure inserting on the sublime
tubercle of the ulna. The posterior band of the UCL is visualized in the SX view of the ulnar
nerve between the medial epicondyle and olecranon process. The posterior band is visualized
as a sling under the ulnar nerve. The transverse or oblique band bridges the medial olecranon
and inferomedial aspect of the coronoid process (Figures 3-22 through 3-24).

A

B

Figure 3-22. Anterior band of the UCL.
(A) Probe placement. (B) Anterior band of
the UCL (white arrows), which originates
from the anteroinferior aspect of the
medial epicondyle (ME) and inserts on
the sublime tubercle of the coronoid
process.

A

B

Figure 3-23. Posterior band of the UCL. (A) Probe placement. (B) Posterior band of the UCL (white arrows), which
originates from the posterior and inferior aspect of the medial epicondyle (ME) and inserts on the medial aspect of the
olecranon process (OL). It appears as a sling under the ulnar nerve (white triangle).

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69

B

Figure 3-24. Transverse band of the UCL. (A) Probe placement. (B) Transverse band of the UCL (white arrows) between the
medial aspect of the tip of olecranon process (OL) and the inferomedial aspect of the coronoid process (CP).

3. Relevant anatomy: The UCL is the main stabilizer against valgus stress when the elbow is
flexed more than 20 degrees. There are 3 bands: anterior, posterior, and transverse or oblique.
The anterior band is the most important and provides the greatest degree of stabilization. The
anterior band of the UCL originates from the anteroinferior aspect of the medial epicondyle
and inserts on the sublime tubercle of the coronoid process of the ulna.2,8 The anterior band
of the UCL has a mean length of 27 mm and an average thickness of 5 mm.8 The posterior
band is a fan-shaped ligament that is best defined at 90 degrees of elbow flexion. The posterior
band originates from the posterior and inferior aspect of the medial epicondyle and inserts
on the medial aspect of the olecranon process. Average thickness of the posterior band ranges
from 5 to 8 mm.8 The posterior band of the UCL forms the floor for the ulnar nerve as it
wraps around the medial epicondyle. The oblique or transverse band of the UCL has limited
contribution to the stability of the elbow as it originates from the medial aspect of the tip of
the olecranon and inserts on the inferomedial aspect of the coronoid process of the ulna, spanning the insertion of the anterior and posterior bands.8
4. Points to remember: Dynamic evaluation of the ligament can be performed if ligament integrity is in question. With the elbow flexed 30 degrees, valgus stress can be applied to visualize
signs of abnormal gapping of the medial joint space or to check for tears of the anterior band
of the UCL.

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Chapter 3

LATERAL ELBOW
Common Extensor Tendon
1. Patient position: Sitting with elbow flexed and forearm mid-supination/pronation
2. Probe/transducer position: The probe is placed on the lateral epicondyle as the bony landmark
and oriented along the common extensor tendon for the LX view. The probe is then rotated
90 degrees to visualize the tendon in the SX view (Figure 3-25).

A

Figure 3-25. Common extensor
tendon. (A) Probe placement. (B) LX
view of the common extensor tendon
(white arrow) showing the lateral
epicondyle (LE) and radial head (RH).
(C) SX view of the common extensor
tendon (white arrow) overlying the
lateral epicondyle (LE).

B

C

3. Relevant anatomy: The common extensor tendon originates from the lateral epicondyle.
4. Points to remember: Deep to the common extensor tendon, the radial collateral ligament
(RCL) can be seen.

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Lateral Collateral Ligament Complex
Relevant anatomy of the region is shown in Figure 3-26.

Figure 3-26. Anatomy of radial/lateral collateral ligament of the elbow. There are 3 ligaments in the lateral collateral
ligament complex: RCL, annular ligament, and lateral UCL.

1. Patient position: Same position as that for common extensor tendon scanning for the RCL.
The elbow is flexed more than 90 degrees and resting on the table for the ulnar attachment of
the annular ligament and lateral UCL scanning.
2. Probe/transducer position: The probe is placed on the lateral epicondyle and oriented along
the common extensor tendon. The RCL is visualized deep to the common extensor tendon
extending between the lateral epicondyle distal surface and annular ligament around the
radial head. The annular ligament with its ulnar attachment is visualized by placing the probe
across the radius and ulna on the dorsal aspect of the forearm. The lateral UCL is visualized by
placing the probe on the posterior aspect of the forearm in oblique orientation to visualize the
LX of the lateral UCL spanning from the ulna to the humerus (Figures 3-27 through 3-29).9

A

B

Figure 3-27. RCL. (A) Probe placement. (B) RCL (white arrows) visualized deep to the common extensor tendon
extending between the lateral epicondyle (LE) distal surface and the annular ligament around the radial head (RH).

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Chapter 3
B

Figure 3-28. Ulnar attachment of the annular ligament. (A) Probe placement.
(B) Annular ligament with its ulnar attachment (white arrows) visualized by
placing the probe across the radius and ulna on the dorsal aspect of the
forearm.

A

B

Figure 3-29. Lateral UCL. (A) Probe placement. (B) Lateral UCL (white arrows)
visualized by placing the probe on the posterior aspect of the forearm in
oblique orientation to visualize the LX of the lateral UCL.

3. Relevant anatomy: There are 3 ligaments in the lateral collateral ligament complex: RCL,
annular ligament, and lateral UCL.
4. Points to remember: There is blending of the fibers of the ligaments of the lateral collateral ligament; therefore, understanding the orientation of the attachment of each ligament helps in identification and better visualization of each component of the lateral collateral ligament complex.

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Radial Nerve
1. Patient position: Sitting with elbow in extension
2. Probe/transducer position: The probe is placed transversely on the anterior elbow, and the brachialis and brachioradialis muscles are identified. The radial nerve is visualized between the
brachialis and brachioradialis muscles in the SX view. The probe is then rotated 90 degrees to
obtain the LX view of the nerve (Figures 3-30 and 3-31).

A

Figure 3-30. SX view of the radial
nerve at the level of the anterior elbow.
(A) Probe placement. (B) Radial nerve
bundle (white arrow) between the
brachioradialis (BRD) and brachialis (BR)
muscles.

B

74
A

Chapter 3
B

Figure 3-31. LX view of the radial nerve at the level of the anterior elbow. (A) Probe placement. (B) LX view of the radial
nerve (white arrows) overlying the anterolateral joint area. (RH = radial head.)

3. Relevant anatomy: At the level of the anterior elbow, radial nerve branches are visualized
between the muscle plane of the brachialis and brachioradialis. The radial nerve appears
hyperechoic and is accompanied with small blood vessels.
4. Points to remember: Color Doppler or power Doppler ultrasound can be used to differentiate
radial nerve branches from accompanying small blood vessels.

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75

POSTERIOR ELBOW
Joint Anatomy
1. Patient position: Sitting with elbow flexed to 90 degrees; posterior elbow pointing toward the
examiner
2. Probe/transducer position: The probe is placed on the posterior aspect of the elbow in the LX to
visualize the joint and olecranon fossa area. The probe is then rotated 90 degrees to visualize
the joint region in the SX view, moving distal to proximal to visualize the joint and then the
olecranon fossa region (Figures 3-32 and 3-33).

A

C

B

Figure 3-32. LX view of the posterior elbow joint. (A) Probe placement. (B)
LX view of the posterior elbow. Structures visualized from distal to proximal:
triceps insertion on the olecranon (OL), joint area (big white arrow), olecranon
fossa (white triangle) with overlying fat pad (hyperechoic). The triceps muscletendon complex (small white arrows) is superficial to the joint and bony
interface. (Tr = trochlea.) (C) Relevant joint anatomy and probe placement.

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Chapter 3

A

B

C
Figure 3-33. SX view of the posterior
elbow joint. (A) Probe placement. (B)
SX view at the olecranon fossa (white
arrow) level. (C) SX view at the joint
level.

3. Relevant anatomy: Structures visualized posteriorly from distal to proximal: triceps insertion
on the olecranon, joint area, olecranon fossa with overlying fat pad, and triceps muscle-tendon
complex superficial to the joint and bony interface.
4. Points to remember: 90-degree flexion helps in better visualization of the joint and fossa
region. Adding extension restricts visualization of the joint and fossa. Adding more flexion
exposes the cartilage-lined humeral trochlea for scanning.

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Triceps Tendon
1. Patient position: Same position as in posterior joint scanning
2. Probe/transducer position: The probe is placed along the triceps tendon in the LX as it attaches
on the olecranon process. The probe is then rotated 90 degrees to scan the tendon in the SX
view (Figures 3-34 and 3-35).

A

B

Figure 3-34. LX view of the triceps tendon. (A) Probe placement. (B) LX view of the triceps tendon (white arrows)
attaching to the olecranon process (OL). Also shown is the joint space (white star) and olecranon fossa (white triangle).

A

B

Figure 3-35. SX view of the triceps tendon. (A) Probe placement. (B) SX view of the
triceps tendon (white arrow) overlying the olecranon process.

3. Relevant anatomy: The long head, lateral head, and medial head of the triceps form a single
tendon distally. The triceps tendon attaches on the olecranon process.
4. Points to remember: 90-degree flexion helps in better visualization of the tendon as it takes the
slack out of the tendon or adds stretch to the tendon to counter anisotropy artifact. Scanning the
tendon in 0-degree extension will result in a darker appearance of the tendon due to anisotropy.

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Chapter 3

Olecranon Bursa
1. Patient position: Same position as in posterior elbow joint scanning
2. Probe/transducer position: The probe is placed in the LX over the olecranon process. The probe
is then rotated 90 degrees to scan the area in the SX view (Figure 3-36).

A

B

Figure 3-36. LX view of the olecranon bursa. (A) Probe placement. (B) The
probe is placed in the LX over the olecranon process. Lots of gel and very light
pressure are needed to scan the olecranon bursa region because increased
pressure will push the fluid away from the probe, resulting in nonvisualization
of the existing effusion. The gel interface between skin and probe helps in
minimal to no deformation of the subcutaneous tissue. Bursa is a potential
space and is not depicted in normal states.

3. Relevant anatomy: The olecranon bursa is a subcutaneous bursa overlying the olecranon process bony surface.
4. Points to remember: Lots of gel and very light pressure are needed to scan the olecranon bursa
region, especially in early stages of bursal effusion or bursitis. Increased pressure will push
the fluid away from the probe, resulting in nonvisualization of the existing effusion. The gel
interface between the skin and probe helps in minimal to no deformation of the subcutaneous
tissue. Bursa is a potential space and is not depicted in normal states.

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REFERENCES
1.
2.
3.
4.
5.
6.
7.
8.
9.

Tagliafico AS, Bignotti B, Martinoli C. Elbow US: anatomy, variants, and scanning technique. Radiology.
2015;275(3):636-650.
Konin GP, Nazarian LN, Walz DM. US of the elbow: indications, technique, normal anatomy, and pathologic
conditions. Radiographics. 2013;33(4):E125-E147.
Kalume Brigido M, De Maeseneer M, Jacobson JA, Jamadar DA, Morag Y, Marcelis S. Improved visualization of
the radial insertion of the biceps tendon at ultrasound with a lateral approach. Eur Radiol. 2009;19(7):1817-1821.
Smith J, Finnoff JT, O’Driscoll SW, Lai JK. Sonographic evaluation of the distal biceps tendon using a medial
approach: the pronator window. J Ultrasound Med. 2010;29(5):861-865.
Eames MH, Bain GI, Fogg QA, van Riet RP. Distal biceps tendon anatomy: a cadaveric study. J Bone Joint Surg
Am. 2007;89(5):1044-1049.
Tagliafico A, Michaud J, Perez MM, Martinoli C. Ultrasound of distal brachialis tendon attachment: normal and
abnormal findings. Br J Radiol. 2013;86(1025):20130004.
Creteur V, Madani A, Sattari A, Bianchi S. Sonography of the pronator teres: normal and pathologic appearances. J Ultrasound Med. 2017;36(12):2585-2597.
Malagelada F, Dalmau-Pastor M, Vega J, Golanó P. Elbow anatomy. In: Doral MN, Karlsson J, eds. Sports
Injuries: Prevention, Diagnosis, Treatment and Rehabilitation. Berlin, Germany: Springer-Verlag; 2014:1-30.
De Maeseneer M, Brigido MK, Antic M, et al. Ultrasound of the elbow with emphasis on detailed assessment of
ligaments, tendons, and nerves. Eur J Radiol. 2015;84(4):671-681.

4
Shoulder
Mohini Rawat, DPT, MS, ECS, OCS, RMSK

Contents
• Anterior Shoulder and Rotator Cuff
º Long Head of the Biceps Tendon
º Subscapularis
º Supraspinatus
º Infraspinatus
º Teres Minor
º Anterior Joint
º Coracoid Process Attachments
º Pectoralis Major
• Posterior Shoulder
º Posterior Joint
º Suprascapular Nerve at the Spinoglenoid Notch
• Acromioclavicular Joint
• Sternoclavicular Joint
• Ligaments
º Coracohumeral Ligament
º Coracoacromial Ligament
• Rotator Interval
• Rotator Cable

- 81 -

Rawat M.
Atlas of Musculoskeletal Ultrasound of the Extremities (pp 81-114).
© 2021 SLACK Incorporated.

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Chapter 4

ANTERIOR SHOULDER AND ROTATOR CUFF
Long Head of the Biceps Tendon
1. Patient position: Sitting with shoulder in neutral position with elbow flexed and resting on a
leg or pillow with no active supination or pronation of the forearm
2. Probe/transducer position: The probe is placed transversely on the anterior aspect of the shoulder to visualize the long head of the biceps tendon in the short axis (SX) view in the bicipital
groove. The probe is then rotated 90 degrees to visualize the tendon in the long axis (LX) view
(Figures 4-1 and 4-2).

A

Figure 4-1. SX view of the long head of
the biceps tendon. (A) Probe placement.
(B) SX view of the long head of the
biceps tendon (white arrow) between
the greater tuberosity (GT) and
lesser tuberosity (LT), with overlying
transverse humeral ligament (white
triangle). Also shown is the anterior
circumflex artery (red arrow). (C) SX of
the long head of the biceps tendon
with color Doppler to show color signal
in the anterior circumflex artery.

B

C

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A

83

B

Figure 4-2. LX view of the long head of the biceps tendon. (A) Probe placement. (B) LX view of the long head of the
biceps tendon (white arrow) overlying the hyperechoic bony interface of the humerus.

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Chapter 4

3. Relevant anatomy: The long head of the biceps tendon originates from the supraglenoid
tubercle and superior labrum. From its origin, the tendon courses obliquely toward the bicipital groove or intertubercular groove. The tendon is stabilized by the medial sling formed by
the coracohumeral ligament and superior glenohumeral ligament. It is intra-articular and
extrasynovial. After it exits the bicipital groove, it joins the short head of the biceps tendon in
the upper arm. After joining the short head of the biceps tendon, both tendons transition into
muscle bellies, continue distally, and form the distal biceps tendon (Figure 4-3).1,2

Figure 4-3. Anterior shoulder anatomy showing the long head of the biceps (LHB) tendon between the intertubercular
groove, covered by the transverse humeral ligament. Distally, the long head of the biceps tendon joins the short head
of the biceps (SHB) and coracobrachialis to form the common biceps brachii muscle belly. The short head of the biceps
and coracobrachialis originate from the coracoid process (CP). The pectoralis minor (PM) attaches to the medial aspect
of the coracoid process. Also shown is the coracoacromial ligament (CAL). (Pec Major = pectoralis major.)

4. Points to remember: The long head of the biceps exhibits anisotropy in the SX and LX views,
which results in a hypoechoic appearance of the tendon. The probe should be placed parallel to
the long head of the biceps to minimize anisotropy in the LX view. In the SX view, a tilting or
fanning movement of the probe can help visualization of the tendon. The anterior circumflex
artery can be seen lateral to the long head of the biceps tendon in the intertubercular groove.

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85

Subscapularis
1. Patient position: Sitting with the elbow flexed to 90 degrees and the shoulder in neutral, then
externally rotated
2. Probe/transducer position: The probe is first positioned over the long head of the biceps tendon in the SX view. The patient is then asked to externally rotate the shoulder to bring the
subscapularis into view. In neutral position, the subscapularis tendon is under the coracoid
process and therefore cannot be visualized. With external rotation, the tendon moves laterally and is accessible for sonographic visualization. For the SX view of the tendon, the probe
is rotated 90 degrees from the LX view (Figures 4-4 and 4-5).

A

B

Figure 4-4. LX view of the
subscapularis. (A) Probe placement. (B)
LX view of the subscapularis tendon
(white arrow) attaching to the lesser
tuberosity (LT).

A

Figure 4-5. SX view of the subscapularis.
(A) Probe placement. (B) SX view of
the subscapularis tendon (white arrow).
Also shown is the lesser tuberosity (LT).

B

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Chapter 4

3. Relevant anatomy: The subscapularis originates from the anterior surface of the scapula and
courses laterally, passing under the coracoid process to insert on the lesser tuberosity where
the tendinous portion blends with the fibers of the joint capsule.3 Subscapularis insertion on
the lesser tuberosity is divided into the tendinous insertion on the superior two-thirds and
the thin membranous muscular insertion on the inferior one-third.4 The footprint of the subscapularis is about 4 cm in length (superior to inferior) and 1.6 cm in width (medial to lateral)
(Figures 4-6 and 4-7).3,4

Figure 4-6. Relevant anatomy of the subscapularis tendon and approximate dimensions of the footprint, which is
about 4 cm in length (superior to inferior) and 1.6 cm in width (medial to lateral).

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87

A

B

Figure 4-7. (A) Panoramic SX view of the subscapularis tendon. (B) Focused
view showing the wide tendon insertion comprising the hyperechoic
tendinous insertion on the superior two-thirds (between double-headed
blue arrow) and hypoechoic thin membranous muscular insertion on the
inferior one-third (between double-headed white arrow).

4. Points to remember: In the SX view of the tendon, tendinous tissue (hyperechoic) is seen interdigitating with muscular tissue (hypoechoic); therefore, the SX view is only used to confirm
tendon defects visualized in the LX view of the tendon.

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Chapter 4

Supraspinatus
1. Patient position: Sitting with the shoulder in internal rotation and hyperextension, with the
elbow flexed and the dorsal aspect of hand on the lower back midline (Crass position) or the
hand on the posterior aspect of the iliac crest or in the back pocket (Middleton or modified
Crass position).5,6 These positions bring the supraspinatus out from beneath the acromion for
sonographic visualization (Figure 4-8).

A

B

Figure 4-8. Patient position for supraspinatus scanning. (A) Crass position.
(B) Middleton or modified Crass position.

2. Probe/transducer position: The probe is placed in the oblique LX along the LX of the supraspinatus tendon with the proximal end of the probe pointing toward the ipsilateral ear. For
SX visualization, the probe is oriented transversely across the tendon (Figures 4-9 and 4-10).

A

B

Figure 4-9. LX view of the supraspinatus tendon. (A) Probe placement. (B) LX view of the supraspinatus (white arrow)
attaching to the superior facet of the greater tuberosity (GT). Just above the supraspinatus tendon, the hyperechoic
subacromial bursa (white triangle) is seen. Overlying the muscle is the deltoid above the bursa. The head of the
humerus is lined by anechoic cartilage (blue arrow).

Shoulder
A

89

B

Figure 4-10. SX view of the
supraspinatus tendon. (A) Probe
placement. (B) SX view of the
supraspinatus tendon (white arrow).

3. Relevant anatomy: The supraspinatus originates from the supraspinous fossa of the scapula
and then courses laterally, passing beneath the acromion to insert on the superior facet of
the greater tuberosity. Posterior fibers of the supraspinatus interdigitate, or blend, with the
infraspinatus tendon. The footprint of the supraspinatus is about 0.6 cm in width (medial to
lateral), 2 cm in medial length (anterior to posterior), and 0.6 cm in lateral length (anterior to
posterior; Figures 4-11 and 4-12).7

Figure 4-11. Relevant anatomy of the rotator cuff showing the supraspinatus, infraspinatus, and teres minor tendons
attaching to the greater tuberosity. Posterior fibers of the supraspinatus blend with the infraspinatus tendon (green
triangle). (ACR = acromion; CL = clavicle; CP = coracoid process; LHB = long head of the biceps.)

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Chapter 4

Figure 4-12. Footprint of the supraspinatus (Supra), infraspinatus (Infra), and teres (T) minor on the greater tuberosity
showing the inferior (I), middle (M), and superior (S) facets of the greater tuberosity. (LT = lesser tuberosity.)

4. Points to remember: The Crass or modified Crass position helps bring the tendon out from
beneath the acromion. In neutral position, a limited view of the distal portion of the tendon
is visible. The posterior portion of the tendon can appear disorganized or may lack normal
parallel fibrillary echotexture due to the transition zone or interdigitating infraspinatus and
supraspinatus fibers. This zone should not be confused with tendon pathology.

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Infraspinatus
1. Patient position: Sitting with a neutral shoulder or holding the opposite arm to stretch the
tendon for better visualization
2. Probe/transducer position:
a. LX view: The probe is placed transversely on the posterior aspect of the scapula over the
infraspinatus muscle belly, just under the spine of the scapula, and then the infraspinatus
is followed laterally as it crosses the glenohumeral joint to insert on the middle facet of the
greater tuberosity of the humerus.
b. SX view: The probe is rotated 90 degrees to visualize the tendon (Figures 4-13 and 4-14).

A

Figure 4-13. LX view of the infraspinatus
tendon. (A) Probe placement. (B) LX
view of the infraspinatus (Infra) muscle
belly overlying the posterior shoulder
joint. (HH = humeral head.) (C) LX view
of the infraspinatus tendon (white
arrow) attaching to the middle facet of
the greater tuberosity (GT).

B

C

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A

Chapter 4
B

Figure 4-14. SX view of the infraspinatus tendon. (A) Probe placement. (B) SX view of the infraspinatus tendon (white
arrow). (GT = greater tuberosity.)

3. Relevant anatomy: The infraspinatus originates from the infraspinous fossa of the scapula and
then courses superiorly and laterally to insert on the greater tuberosity. The footprint of the
infraspinatus is about 1.2 cm in width (medial to lateral), 2.3 cm in medial length (anterior to
posterior), and 2.6 cm in lateral length (anterior to posterior).7
4. Points to remember: Some cortical irregularities under the infraspinatus at the level just proximal to the greater tuberosity is a normal finding and should not be confused with erosions.

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Teres Minor
1. Patient position: Same as for the infraspinatus
2. Probe/transducer position: After obtaining the infraspinatus LX view, the probe is moved
inferiorly to scan the teres minor tendon, which is immediately inferior to the infraspinatus
tendon. The SX view is obtained by rotating the probe 90 degrees from the LX view (Figures
4-15 and 4-16).

A

Figure 4-15. LX view of the teres minor
tendon. (A) Probe placement. (B) LX
view of the teres minor tendon (white
arrow) attaching to the inferior facet of
the greater tuberosity (GT).

B

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Chapter 4
B

Figure 4-16. SX view of the teres minor tendon. (A) Probe placement. (B) SX view of the teres minor tendon (white
arrow). (GT = greater tuberosity.)

3. Relevant anatomy: The teres minor originates from the dorsal aspect of the lateral border of
the scapula and courses laterally to attach to the inferior facet of the greater tuberosity. It is the
most posterior tendon of the rotator cuff and functions to externally rotate the humerus.6 It
has muscular attachment to the posterior capsule and the humerus with a smaller tendinous
insertion. Unlike the supraspinatus and infraspinatus, the teres minor does not blend with
infraspinatus fibers posteriorly.8 The teres minor has a triangular footprint with a tapered
inferior end. The footprint of the teres minor is about 2.9 cm in length (superior to inferior)
and 2.1 cm in width (medial to lateral).9
4. Points to remember: The teres minor is about half the size of the infraspinatus tendon. An
intact teres minor is important for activities of daily living when there is a massive irreparable
rotator cuff tear.8

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95

Anterior Joint
1. Patient position: Supine or sitting with external rotation of the shoulder
2. Probe/transducer position: The probe is placed transversely on the anterior aspect of the shoulder, distal to the coracoid process, to visualize the anterior joint area (Figure 4-17).

A

B

Figure 4-17. Anterior shoulder joint. (A) Probe placement. (B) Anterior glenohumeral joint (white star), glenoid (white
arrow), cartilage lining the humeral head (HH; yellow arrow), and subscapularis muscle tendon complex (red arrow).

3. Relevant anatomy: The anterior joint is visualized deep to the subscapularis muscle-tendon
complex.
4. Points to remember: Ultrasound gives a limited view of the anterior joint and is therefore not
the first choice for imaging intra-articular pathology.

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Chapter 4

Coracoid Process Attachments
1. Patient position: Seated with neutral shoulder
2. Probe/transducer position: The probe is placed transversely over the coracoid process and
moved just distal enough to lose the view of the coracoid process to visualize the tendon
attachments in the SX view. For the LX view, the probe is aligned along the structure of interest with the coracoid process as a bony landmark (Figures 4-18 and 4-19).

A

B

Figure 4-18. Short head of the biceps
and coracobrachialis attachment at the
coracoid process. (A) Probe placement.
(B) SX view of the hyperechoic
tendinous portion of the short head
of the biceps (white arrow) and hypoechoic muscular portion of the coracobrachialis (red arrow). Laterally, the
subscapularis can be seen (white triangle).

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A

97

B

Figure 4-19. LX view of the pectoralis
minor. (A) Probe placement. (B) LX view
of the pectoralis minor (white arrows)
attaching to the coracoid process (CP).

3. Relevant anatomy: The short head of the biceps and coracobrachialis originate from the anterior aspect of the tip of the coracoid process. The pectoralis minor originates from the medial
aspect of the coracoid process.
4. Points to remember: The coracoid process gives attachment to multiple structures. It is important to note that very little movement of the probe is required to scan structures attaching to
the coracoid process.

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Chapter 4

Pectoralis Major
1. Patient position: Sitting
2. Probe position: The probe is placed transversely over the anterior shoulder to visualize the
long head of the biceps in the SX in the groove. The long head of the biceps is then followed
distally until the hyperechoic tendon of the pectoralis major is seen crossing over the long
head of the biceps. The SX view is obtained by rotating the probe 90 degrees from the LX view
(Figures 4-20 and 4-21).
A

B

Figure 4-20. LX view of the pectoralis
major. (A) Probe placement. The long
head of the biceps is first identified
at the intertubercular groove, then
followed distally until the LX of the
pectoralis tendon is visualized crossing
above the long head of the biceps in a perpendicular direction. (B) LX view of the pectoralis major (white arrow). The
muscle-tendon complex of the long head of the biceps (yellow arrow) is seen under the pectoralis major tendon.

A

B

Figure 4-21. SX view of the pectoralis major. (A) Probe placement. (B) SX view of the pectoralis major tendon (white
arrow).

3. Relevant anatomy: The pectoralis major is attached to the lateral lip of the intertubercular
groove.

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99

POSTERIOR SHOULDER
Posterior Joint
1. Patient position: Sitting
2. Probe/transducer position: The probe is placed transversely on the posterior aspect of the glenohumeral joint at the level of the infraspinatus muscle-tendon complex. Initially, the probe
is placed on the posterior aspect of the scapula just below the spine of the scapula to visualize
the infraspinatus muscle, and then the muscle is followed laterally as it crosses the posterior
glenohumeral joint (Figure 4-22).

A

B

Figure 4-22. Posterior glenohumeral
joint showing the glenoid (GL), glenoid
labrum (white arrow), and anechoic
cartilage lining the humeral head (red
arrow) and overlying infraspinatus (Inf).

3. Relevant anatomy: The infraspinatus muscle-tendon complex overlies the posterior joint.
4. Points to remember: To widen the joint space for better visualization, the patient is asked to
reach across and hold the opposite arm.

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Chapter 4

Suprascapular Nerve at the Spinoglenoid Notch
1. Patient position: Sitting
2. Probe/transducer position: The probe is placed on the posterior glenohumeral joint, and then
attention is focused on the spinoglenoid notch, which is just medial to the posterior glenohumeral joint (Figure 4-23).5

A

B

Figure 4-23. Suprascapular nerve at the spinoglenoid notch. (A) Probe placement. (B) The suprascapular nerve (red
arrow) with vessels (red area) sits deep in the spinoglenoid notch.

3. Relevant anatomy: The suprascapular nerve with vessels sits deep in the spinoglenoid notch,
where its terminal branches enter the infraspinatus muscle.10
4. Points to remember: Color Doppler is helpful in differentiating nerve from artery in the
spinoglenoid notch because the nerve and vascular bundle are very small structures and may
be difficult to distinguish with B-mode imaging.

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ACROMIOCLAVICULAR JOINT
1. Patient position: Sitting with shoulder in neutral position
2. Probe/transducer position: The probe is placed over the acromioclavicular (AC) joint in transverse orientation to bridge the articulating ends of the acromion and clavicle (Figure 4-24).

A

B

C

Figure 4-24. AC joint. (A) Probe placement: top view of the shoulder. (B)
Probe placement: front view of the shoulder. (C) AC joint. (ACR = acromion;
CL = clavicle.)

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Chapter 4

3. Relevant anatomy: The AC joint is a diarthrodial joint between the medial facet of the acromion and the lateral end of the clavicle. Articulating surfaces are lined with fibrocartilage.
There may be an intra-articular disk between the articulating surfaces. The AC joint is surrounded by a fibrous capsule that extends 2.8 mm lateral to the medial facet of the acromion
and 3.5 mm medial to the lateral clavicle articulating surface, with a mean capsule width
ranging from 1.6 to 2.9 mm.11 The capsule is reinforced by the superoposterior AC ligament,
which is well defined and well developed, and the anteroinferior AC ligament, which is less
developed. Superoposterior fibers run obliquely across the joint between the anterosuperior
aspect of the acromion to the posterior part of the distal end of the clavicle, at an angle about
30 degrees to the joint surface (Figure 4-25).12

Figure 4-25. Relevant anatomy of the AC joint showing the superoposterior AC ligament (green) and AC joint capsule
(yellow). (ACR = acromion; CL = clavicle.)

4. Points to remember: Standing behind the patient for an AC joint scan helps with proper probe
placement over the AC joint in the direction of the superoposterior band of the AC ligament,
thereby visualizing the joint, capsule, and ligament in one view.

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STERNOCLAVICULAR JOINT
1. Patient position: Sitting
2. Probe/transducer position: The probe is placed on the sternoclavicular (SC) joint bridging
the clavicle and manubrium. The orientation of the probe is oblique, with the medial end
of the probe rotated downward to align the probe along the LX of the articulating surface
(Figure 4-26).
A

B

Figure 4-26. SC joint. (A) Probe placement. (B) SC joint.

3. Relevant anatomy: The SC joint is a double arthrodial synovial joint. There is an articular disk
interposed between articulating surfaces of the clavicle and manubrium. The articular disk
attaches to the posterosuperior aspect of the medial articulating surface of the clavicle and
the anterosuperior aspect of the first costal cartilage, with remaining disk covered by capsule.
The disk is thicker in the periphery and at the attachment sites.13 The ligaments around the
joint area include the anterior SC ligament, posterior SC ligament, costoclavicular ligament,
and interclavicular ligament.14 The posterior SC ligament is the primary stabilizer of the SC
joint (Figure 4-27).15

Figure 4-27. Relevant anatomy of the SC joint.

4. Points to remember: Movement occurs in the anteroposterior and vertical axis. In elevation
and depression, movement occurs between the articular disk and clavicle. In protraction and
retraction, movement occurs between the articular disk and sternum.13

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Chapter 4

LIGAMENTS
Coracohumeral Ligament
1. Patient position: Sitting with shoulder in external rotation
2. Probe/transducer position: The probe is placed over the long head of the biceps in the SX and
then moved medially to visualize the coracoid process. Then the medial end of the probe is
fixed at the coracoid process, and the lateral end of the probe is rotated toward the humerus
to scan the coracohumeral ligament (Figure 4-28).

A

Figure 4-28. Coracohumeral ligament.
(A) Probe placement. (B) Coracohumeral
ligament (white arrow) attaching on the
lateral aspect of the coracoid process
(CP). (Subscap = subscapularis.)

B

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105

3. Relevant anatomy: The coracohumeral ligament originates from the lateral aspect of the base of
the coracoid process. Its lateral insertion varies greatly. The coracohumeral ligament inserts into
the rotator interval and into the supraspinatus tendon. It also envelops the subscapularis tendon
and is an important structure responsible for the stability of the glenohumeral joint. Based on
the histologic features, the coracohumeral ligament is more capsular than ligamentous. The coracohumeral ligament is composed of irregular and sparse fibers and interstitial vascularity and
contains type III collagen, which gives flexibility to the ligament (Figures 4-29 and 4-30).16,17

Figure 4-29. Coracohumeral ligament (CHL) attachments. The coracohumeral ligament originates from the lateral
aspect of the base of the coracoid process (CP). Its lateral insertion varies greatly. It inserts into the rotator interval and
into the supraspinatus tendon (SUP). It also envelops the subscapularis tendon (SUB). (INF = infraspinatus; LHB = long
head of the biceps.)

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Chapter 4

Figure 4-30. Relevant ligament anatomy of the anterior shoulder. (LHB = long head of the biceps.)

4. Points to remember: The coracohumeral ligament is best visualized close to its origin at the
coracoid process. The ligament then fans laterally and sends its fibers in different directions
to different structures; therefore, it is difficult to visualize laterally.

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Coracoacromial Ligament
1. Patient position: Sitting
2. Probe/transducer position: The probe is placed over the long head of the biceps in the SX and
then moved medially to visualize the coracoid process. Then the medial end of the probe is
fixed at the coracoid process, and the lateral end of the probe is rotated superiorly to bring the
acromion in the view. The coracoacromial ligament is visualized between the coracoid process
and acromion (Figure 4-31).

A

Figure
4-31.
Coracoacromial
ligament. (A) Probe placement. (B)
Coracoacromial ligament (white arrow)
between the acromion (ACR) laterally
and the coracoid process (CP) medially.

B

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Chapter 4

3. Relevant anatomy: The coracoacromial ligament has 2 bundles: the anterior bundle, which is
more prominent, and the posterior bundle, which attaches medial to the anterior bundle on the
coracoid process. The 2 bundles have a common attachment site at the acromion (Figure 4-32).18

Figure 4-32. Relevant anatomy of the coracoacromial ligament (CAL) and subacromial space. (CHL = coracohumeral
ligament; LHB = long head of the biceps; SUBSCAP = subscapularis.)

4. Points to remember: A forward head and rounded shoulder posture makes it difficult to scan
the ligament. An upright posture is recommended for better visualization of the ligament.

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109

ROTATOR INTERVAL
1. Patient position: Sitting in modified Crass position
2. Probe/transducer position: The probe is placed in the oblique SX view over the anterosuperior
aspect of the shoulder (Figure 4-33).

A

B

Figure 4-33. Rotator interval. (A) Probe
placement. (B) The rotator interval
is the anterosuperior aspect of the
capsule, which is reinforced externally
by the coracohumeral ligament (yellow
arrow) and reinforced internally by the
superior glenohumeral ligament (red
arrow). Contents of the rotator interval include the coracohumeral ligament, superior glenohumeral ligament,
glenohumeral capsule, and long head of the biceps (white star). The subscapularis (white triangle) and supraspinatus
(white arrow) are also seen.

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Chapter 4

3. Relevant anatomy: The rotator interval is located in the anterosuperior aspect of the shoulder
in a triangular area. The base of the triangle is medially at the coracoid process, the superior
border of the subscapularis forms the inferior border, the anterior margin of the supraspinatus
forms the superior border, and the transverse humeral ligament between the intertubercular
groove forms the apex. The rotator interval is the anterosuperior aspect of the capsule, which is
reinforced externally by the coracohumeral ligament and reinforced internally by the superior
glenohumeral ligament and capsular fibers, which blend together and insert medially and laterally to the bicipital groove. The contents of the rotator interval include the coracohumeral ligament, superior glenohumeral ligament, glenohumeral capsule, and long head of the biceps.19
The rotator interval plays an important role in the stability of the glenohumeral joint and
biceps tendon. Injury or pathology of the rotator interval can lead to contractures, instability,
or pathological conditions of the glenohumeral joint and biceps tendon (Figure 4-34).20,21

Figure 4-34. Relevant anatomy of the rotator interval, which is reinforced externally by the coracohumeral ligament
(CHL) and reinforced internally by the superior glenohumeral ligament (SGHL) and capsular fibers, which blend
together and insert medially and laterally to the bicipital groove. (LHB = long head of the biceps.)

4. Points to remember: While scanning the rotator interval region, it is important to remember
that anisotropy may affect the imaging; therefore, a tilting movement of the probe is required
for better visualization of the structures. It is important to not mistake anisotropy that presents as a hypoechoic signal in tissue for an abnormal signal. Color Doppler ultrasound should
be used in scanning the rotator interval region for signs of neoangiogenesis or vascularity.

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ROTATOR CABLE
1. Patient position: Same position as in a supraspinatus scan
2. Probe/transducer position: The probe is placed in the SX view of the supraspinatus tendon to
visualize the cable in the LX at the level of humeral head, where the cable is visualized over
the articular cartilage (Figures 4-35 and 4-36).

A

B

Figure 4-35. LX view of the rotator
cable. (A) Probe placement. (B) LX view
of the rotator cable (white arrows)
under the supraspinatus tendon.

A

Figure 4-36. SX view of the rotator
cable. (A) Probe placement. (B) In the SX
view, the rotator cable (white arrows)
appears as thickening of the capsule
under the supraspinatus tendon.

B

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3. Relevant anatomy: The rotator cable is a capsuloligamentous complex, which is essential for
normal biomechanics and kinematics of the shoulder.22 The rotator cable is a band of transversely oriented fibers of the coracohumeral ligament. These fibers course posteriorly on the
undersurface of the supraspinatus and infraspinatus tendons and terminate at the superior
margin of the teres minor muscle.23 The cable marks out the region of the overlying tendon
that is relatively hypovascular, known as the rotator crescent. Tendon tears most frequently
occur in the region overlying the rotator crescent. This cable-crescent region acts like a suspension bridge, where biomechanical load is transmitted to the cable region so that the stress
is distributed over the humeral head region between the anterior and posterior anchors of the
rotator cable, thereby assisting the rotator cuff tendons.23 In the absence of rotator cuff tendons, an intact cable attenuates the adverse consequence on the glenohumeral biomechanics
(Figures 4-37 and 4-38).23

Figure 4-37. Superior view of the shoulder without the overlying tendons. The rotator cable is a capsuloligamentous
complex formed by a band of transversely oriented fibers of the coracohumeral ligament. (GT = greater tuberosity;
HH = humeral head; LHB = long head of the biceps; LT = lesser tuberosity; Subscap = subscapularis.)

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Figure 4-38. Posterior view of the rotator cuff showing the rotator cable, which courses posteriorly on the
undersurface of the supraspinatus (Supra) and infraspinatus (Infra) tendons and terminates at the superior margin of
the teres (T) minor muscle. (GT = greater tuberosity; LHB = long head of the biceps; LT = lesser tuberosity.)

4. Points to remember: The rotator crescent provides capsular attachment to the greater tuberosity, and the rotator cable distributes the force to prevent capsular disruption from the humerus.
The rotator cable exerts the compressive force to stabilize the humeral head.22

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Chapter 4

REFERENCES
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8.
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10.
11.
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Virk MS, Cole BJ. Proximal biceps tendon and rotator cuff tears. Clin Sports Med. 2016;35(1):153-161.
Varacallo M, Mair SD. Biceps tendon dislocation and instability. In: StatPearls. Treasure Island, FL: StatPearls
Publishing; 2019. Updated March 13, 2020.
Ide J, Tokiyoshi A, Hirose J, Mizuta H. An anatomic study of the subscapularis insertion to the humerus: the
subscapularis footprint. Arthroscopy. 2008;24(7):749-753.
Arai R, Sugaya H, Mochizuki T, Nimura A, Moriishi J, Akita K. Subscapularis tendon tear: an anatomic and
clinical investigation. Arthroscopy. 2008;24(9):997-1004.
Jacobson JA. Shoulder US: anatomy, technique, and scanning pitfalls. Radiology. 2011;260(1):6-16.
Lee MH, Sheehan SE, Orwin JF, Lee KS. Comprehensive shoulder US examination: a standardized approach
with multimodality correlation for common shoulder disease. Radiographics. 2016;36(6):1606-1627.
Lumsdaine W, Smith A, Walker RG, Benz D, Mohammed KD, Stewart F. Morphology of the humeral insertion
of the supraspinatus and infraspinatus tendons: application to rotator cuff repair. Clin Anat. 2015;28(6):767-773.
Williams MD, Edwards TB, Walch G. Understanding the importance of the teres minor for shoulder function:
functional anatomy and pathology. J Am Acad Orthop Surg. 2018;26(5):150-161.
Curtis AS, Burbank KM, Tierney JJ, Scheller AD, Curran AR. The insertional footprint of the rotator cuff: an
anatomic study. Arthroscopy. 2006;22(6):609.e1.
Faruch Bilfeld M, Lapègue F, Sans N, Chiavassa Gandois H, Laumonerie P, Larbi A. Ultrasonography study of
the suprascapular nerve. Diagn Interv Imaging. 2017;98(12):873-879.
Saccomanno MF, De Ieso C, Milano G. Acromioclavicular joint instability: anatomy, biomechanics and evaluation. Joints. 2014;2(2):87-92.
Nakazawa M, Nimura A, Mochizuki T, Koizumi M, Sato T, Akita K. The orientation and variation of the acromioclavicular ligament: an anatomic study. Am J Sports Med. 2016;44(10):2690-2695.
Dhawan R, Singh RA, Tins B, Hay SM. Sternoclavicular joint. Shoulder Elbow. 2018;10(4):296-305.
van Tongel A, MacDonald P, Leiter J, Pouliart N, Peeler J. A cadaveric study of the structural anatomy of the
sternoclavicular joint. Clin Anat. 2012;25(7):903-910.
Lee JT, Campbell KJ, Michalski MP, et al. Surgical anatomy of the sternoclavicular joint: a qualitative and quantitative anatomical study. J Bone Joint Surg Am. 2014;96(19):e166.
Arai R, Nimura A, Yamaguchi K, et al. The anatomy of the coracohumeral ligament and its relation to the subscapularis muscle. J Shoulder Elbow Surg. 2014;23(10):1575-1581.
Yang HF, Tang KL, Chen W, et al. An anatomic and histologic study of the coracohumeral ligament. J Shoulder
Elbow Surg. 2009;18(2):305-310.
Chahla J, Marchetti DC, Moatshe G, et al. Quantitative assessment of the coracoacromial and the coracoclavicular ligaments with 3-dimensional mapping of the coracoid process anatomy: a cadaveric study of surgically
relevant structures. Arthroscopy. 2018;34(5):1403-1411.
Tamborrini G, Möller I, Bong D, et al. The rotator interval—a link between anatomy and ultrasound. Ultrasound
Int Open. 2017;3(3):E107-E116.
Hunt SA, Kwon YW, Zuckerman JD. The rotator interval: anatomy, pathology, and strategies for treatment. J Am
Acad Orthop Surg. 2007;15(4):218-227.
Petchprapa CN, Beltran LS, Jazrawi LM, Kwon YW, Babb JS, Recht MP. The rotator interval: a review of anatomy, function, and normal and abnormal MRI appearance. AJR Am J Roentgenol. 2010;195(3):567-576.
Adams CR, DeMartino AM, Rego G, Denard PJ, Burkhart SS. The rotator cuff and the superior capsule: why we
need both. Arthroscopy. 2016;32(12):2628-2637.
Bureau NJ, Blain-Paré E, Tétreault P, Rouleau DM, Hagemeister N. Sonographic visualization of the rotator
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infiltration and atrophy, and functional outcome. J Ultrasound Med. 2016;35(9):1899-1905.

5
Ankle and Foot
Mohini Rawat, DPT, MS, ECS, OCS, RMSK

Contents
• Anterior Ankle
º Joint Anatomy
º Tendons
º Anterior Inferior Tibiofibular Ligament
º Anterior Talofibular Ligament
º Deep Peroneal Nerve
• Lateral Ankle
º Peroneal Tendons
º Calcaneofibular Ligament
• Medial Ankle
º Tarsal Tunnel and Its Contents
º Deltoid Ligament Complex
• Posterior Ankle
º Achilles Tendon
º Posterior Inferior Tibiofibular Ligament
º Posterior Talofibular Ligament

- 115 -

Rawat M.
Atlas of Musculoskeletal Ultrasound of the Extremities (pp 115-158).
© 2021 SLACK Incorporated.

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Chapter 5

• Hindfoot
º Subtalar Joint
▪ Anterior Subtalar Joint (Medial Approach)
▪ Posterior Subtalar Joint (Medial Approach)
▪ Posterior Subtalar Joint (Lateral Approach)
▪ Posterior Subtalar Joint (Posterior Approach)
º Plantar Fascia
• Midfoot
º Lateral Ligaments
º Medial Ligaments
• Forefoot
º Metatarsophalangeal Joint and Plantar Plate
º Intermetatarsal Space

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117

ANTERIOR ANKLE
Joint Anatomy
1. Patient position: Supine with the ankle in slight plantar flexion
2. Probe/transducer position: The long axis (LX) view/longitudinal view is obtained by placing
the probe longitudinally along the anterior ankle (Figure 5-1).

A

B

Figure 5-1. Ankle joint. (A) Probe placement. (B) Ultrasound image of the tibiotalar joint. From proximal to distal, bony
landmarks are visualized in the following order: the distal tibia, talar dome, and talar head. Anechoic cartilage (white
arrow) lines the talar dome surface. Overlying the cartilage, a hyperechoic fat pad (white star) is visualized.

3. Relevant anatomy: From proximal to distal, bony landmarks are visualized in the following order: distal tibia, talar dome, and talar head. The talar dome presents with an anechoic
cartilage-lined surface. Overlying the cartilage, a hyperechoic fat pad is visualized.
4. Points to remember: Anterior joint effusions are visualized as hypoechoic/anechoic signals in
the tibiotalar joint area.

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Chapter 5

Tendons
Relevant anatomy is shown in Figure 5-2.

Figure 5-2. Relevant anatomy of the anterior tendons of the ankle.

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119

1. Patient position: Supine with the ankle in slight plantar flexion
2. Probe/transducer position:
a. Short axis (SX) view/transverse view: The probe is placed transversely on the anterior ankle at
the level of the talus to visualize the tendons on the anterior aspect of the ankle (Figure 5-3).

A

B

Figure 5-3. SX view of the anterior tendons of the ankle. (A) Probe placement. (B) SX view of the tendons. From
medial to lateral, they are the tibialis anterior (white arrow), EHL (yellow arrow), and EDL (red arrow). The EHL shows
the hyperechoic tendon and hypoechoic muscle part. The deep peroneal nerve (white triangle) is present deep to the
tendons in the middle, right under the EHL tendon. (A = dorsalis pedis artery.)

b. The LX view/longitudinal view can be obtained along each tendon to look for any focal
tendon pathology (Figures 5-4 through 5-6).

A

B

Figure 5-4. LX view of the tibialis anterior tendon. (A) Probe placement. (B) LX view of the tibialis anterior tendon
(white arrow).

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B

Figure 5-5. LX view of the EHL tendon. (A) Probe placement. (B) LX view of the EHL tendon (white arrows). The
underlying muscle of the EHL (white stars) can be seen. (A = dorsalis pedis artery.)

A

B

Figure 5-6. LX view of the EDL tendon. (A) Probe placement. (B) LX view of the EDL tendon (white arrow).

3. Relevant anatomy: There are 3 tendons on the anterior aspect of the ankle. From medial to
lateral, they are the tibialis anterior, extensor hallucis longus (EHL), and extensor digitorum
longus (EDL). The dorsalis pedis artery and deep peroneal nerve are present deep to the tendons in the middle, right under the EHL tendon.1
4. Points to remember: The synovial sheath of the extensor tendons of the ankle typically does not
contain fluid. Tenosynovitis should be considered in the presence of even a small amount of
fluid.1

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Anterior Inferior Tibiofibular Ligament
Relevant anatomy is shown in Figure 5-7.

Figure 5-7. Relevant anatomy of the anterolateral ligaments of the ankle.

1. Patient position: Ankle in slight plantar flexion and inversion
2. Probe/transducer position: The probe is placed along the ligament bridging the distal tibial and
the fibula (Figure 5-8).
A

B

Figure 5-8. Anterior inferior tibiofibular ligament. (A) Probe placement. (B) Anterior inferior tibiofibular ligament
(white arrow) between the tibia and fibula.

3. Relevant anatomy: The ligament is obliquely oriented from the anterior margin of the fibular
tubercle of the tibial to the anterior margin of the distal fibular shaft and lateral malleolus.
The thickness of the ligament ranges from 2.6 to 4 mm, and the length measures about 12 to
15.5 mm.2,3 The ligament is a flattened band and is partially blended with the anterior interosseous membrane.4
4. Points to remember: The anterior inferior tibiofibular ligament has an important role in the
stability of the distal tibiofibular joint. Injury to this ligament may result in instability and
widening of the ankle mortise.2

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Anterior Talofibular Ligament
1. Patient position: Ankle in slight plantar flexion and inversion
2. Probe/transducer position: The probe is placed along the ligament bridging the talus and fibula
anteriorly (Figure 5-9).

A

B

Figure 5-9. Anterior talofibular ligament. (A) Probe placement. (B) Anterior talofibular ligament (white arrow)
between the talus and fibula.

3. Relevant anatomy: The ligament connects the anterolateral border of the lateral malleolus and
lateral surface of the talar neck. Some fibers of the ligament blend with the tibiotalar capsule.
Its primary function is to restrain the anterior displacement of the talus with respect to the
fibula and tibia.2,4
4. Points to remember: The anterior talofibular ligament is the most commonly injured ligament
of the lateral collateral complex of the ankle.2

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Deep Peroneal Nerve
1. Patient position: Foot in neutral or slight plantar flexion
2. Probe/transducer position: The probe is placed transversely over the anterior ankle to visualize 3 tendons; from medial to lateral, they are the tibialis anterior, EHL, and EDL. The deep
peroneal nerve is seen deep to the EHL tendon, accompanied with an artery (Figure 5-10).

A

B

C

Figure 5-10. Deep peroneal nerve. (A) Probe placement. (B) The deep peroneal nerve (white arrow) is seen deep to
the EHL tendon, accompanied by the dorsalis pedis artery (white A) at the level of anterior ankle. (C) Color Doppler
ultrasound image showing the dorsalis pedis artery (black A) and deep peroneal nerve (white arrow).

3. Relevant anatomy: The deep peroneal nerve and dorsalis pedis artery are together at the level
of the anterior ankle. The deep peroneal nerve gives a motor branch to the extensor digitorum
brevis and extensor hallucis brevis in the foot. It also gives sensory branches to the ankle joint
and dorsal aspect of the first web space.
4. Points to remember: The branching pattern of the deep peroneal nerve may differ. In some
ankles, the dorsalis pedis artery may be accompanied by medial and lateral branches of the
deep peroneal nerve at the level of the anterior ankle.

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LATERAL ANKLE
Peroneal Tendons
Relevant anatomy is shown in Figure 5-11.

Figure 5-11. Relevant anatomy of the peroneal tendons.

1. Patient position: Prone with the foot over the edge of the table
2. Probe/transducer position:
a. SX view: The probe is placed transversely between the lateral malleolus and the Achilles
tendon to visualize the peroneal tendons in stacked formation behind the fibula.

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b. LX view: From the SX view, the probe is rotated 90 degrees to align with the LX of the
tendons (Figures 5-12 through 5-15).

A

B

Figure 5-12. SX view of the peroneal tendons. (A) Probe placement. (B) SX view of the peroneal tendons behind the
lateral malleolus. Shown are the peroneus longus (yellow arrow), peroneus brevis (white arrow), and peroneus brevis
muscle (white star).

A

B

Figure 5-13. LX view of the peroneal tendons. (A) Probe placement. (B) LX view of the peroneal tendons behind the
lateral malleolus. Shown are the peroneus longus (yellow arrow) and peroneus brevis (white arrow).

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Figure 5-14. SX view of the peroneal tendons from the proximal to distal levels around the lateral malleolus and lateral
foot. (PB = peroneus brevis; PL = peroneus longus.)

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A

B

Figure 5-15. (A) LX view of the peroneal tendons from the proximal to distal level around the lateral malleolus and
lateral foot. The peroneus longus (PL) tendon wraps around the lateral foot to enter the plantar aspect of the foot
(note the hypoechoic tendon due to anisotropy). The peroneus brevis (PB) tendon attaches on the lateral aspect of the
tuberosity at the base of fifth metatarsal (MT). (B) LX view of the peroneus longus on the plantar aspect of the foot.
(i) Relevant anatomy. (ii) The peroneus longus tendon (white arrows) from the lateral aspect to the plantar aspect of
the foot, inserting on the plantar aspect of the base of first metatarsal. (iii) Probe placement.

3. Relevant anatomy: The peroneus brevis is deeper than the peroneus longus. At the level of the
distal end of the fibula or tip of the lateral malleolus, the calcaneofibular ligament (CFL) runs
deep to the peroneal tendons in a direction roughly perpendicular to the tendons.
4. Points to remember: The peroneal tendons take a sharp turn around the tip of the lateral malleolus as they course along the lateral border of the foot. An anomalous muscle, the peroneus
quartus, may be present as a third tendon, along with the peroneus brevis and longus.5 It
should not be confused with a split tear of the peroneus brevis.

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Calcaneofibular Ligament
1. Patient position: Ankle in slight dorsiflexion
2. Probe/transducer position: The probe is placed along the CFL, bridging the tip of the lateral
malleolus and the lateral surface of the calcaneus. Alternatively, the peroneal tendons can be
followed in the SX view as they wrap around the lateral malleolus, and the CFL is seen under
the tendons, between the lateral malleolus and calcaneus (Figure 5-16).

A

B

C

D

Figure 5-16. CFL. (A) Probe placement.
(B) LX view of the CFL (white arrow)
with overlying peroneal tendons in
the SX view. (C) Relevant anatomy and
probe placement. (D) SX view of the
CFL (white arrow) with overlying peroneal tendons in the LX view. Due to anisotropy, the CFL appears hypoechoic.
Tilting the probe can make the CFL hypoechoic or hyperechoic.

3. Relevant anatomy: The CFL is a long cord-like ligament that runs deep to the peroneal tendons
(see Figure 5-7). The primary function of the CFL is to restrain inversion of the calcaneus with
respect to the fibula.2
4. Points to remember: With ankle dorsiflexion, the peroneal tendons move superficially. If there
is no superficial displacement of the peroneal tendons upon dorsiflexion, a tear of the CFL
should be considered.

Ankle and Foot

MEDIAL ANKLE
Tarsal Tunnel and Its Contents
Relevant anatomy is shown in Figure 5-17.

Figure 5-17. Relevant anatomy of the medial ankle/tarsal tunnel structures.

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1. Patient position: Supine
2. Probe/transducer position: The probe is placed along the flexor retinaculum at the level of the
medial malleolus to scan the contents of the tarsal tunnel in the SX view (Figure 5-18). The
LX view of each structure can be obtained by rotating the probe 90 degrees from the SX view
(Figures 5-19 through 5-22).

A

B

Figure 5-18. SX view of the tarsal tunnel
(medial ankle). (A) Probe placement. (B)
SX view of the medial ankle showing
the tibialis posterior tendon (white
arrow), FDL tendon (red arrow), posterior tibial artery (white A), posterior tibial nerve (yellow arrow), vein (V), and FHL
tendon (blue arrow) with hypoechoic muscle under the tendon. Also shown is the flexor retinaculum (white triangle).

A

B

Figure 5-19. LX view of the
tibialis posterior tendon.
(A) Probe placement.
(B) LX view of the tibialis
posterior tendon (white
arrow).

A

Figure 5-20. LX view of
the FDL tendon. (A) Probe
placement. (B) LX view of the
FDL tendon (white arrow).

B

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131

B

Figure 5-21. LX view of the posterior tibial nerve. (A) Probe placement. (B) LX view of the posterior tibial nerve (white
arrow). (A = artery.)

A

B

Figure 5-22. LX view of the FHL tendon. (A) Probe placement on the posteromedial aspect of the ankle along the
posterior ankle joint. (B) LX view of the FHL tendon (white arrow).

3. Relevant anatomy: From anterior to posterior, structures are arranged in the following order:
tibialis posterior, flexor digitorum longus (FDL), posterior tibial artery, posterior tibial nerve,
vein, and flexor hallucis longus (FHL).
4. Points to remember: The FHL tendon should not be confused with the posterior tibial nerve
because they both appear as hyperechoic structures at this level. Using dynamic examination
by passively flexing and extending the big toe may help differentiate the FHL from the posterior tibial nerve.

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Deltoid Ligament Complex
The deltoid ligament, or medial collateral ligament, complex has 2 layers: (1) a deep layer that
extends from the medial malleolus to the talus and consists of the anterior and posterior tibiotalar
ligaments and (2) a superficial layer in a triangular shape that extends from the medial malleolus
to the navicular bone, spring ligament, and calcaneus. The superficial layer consists of the tibionavicular ligament, tibiospring ligament, and tibiocalcaneal ligament (Figure 5-23).

Figure 5-23. Relevant anatomy of the deltoid ligament.

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1. Patient position: Ankle in dorsiflexion for posterior tibiotalar (Figure 5-24), tibiocalcaneal
(Figure 5-25), and tibiospring ligaments (Figure 5-26). Ankle in plantar flexion for anterior
tibiotalar (Figure 5-27) and tibionavicular ligaments (Figure 5-28). Ankle in dorsiflexion for
medial talocalcaneal ligament (Figure 5-29).

A

B

C

Figure 5-24. Posterior tibiotalar ligament. (A) Probe placement with the
ankle in dorsiflexion. (B) Posterior tibiotalar ligament (white arrow) between
the tibia and the talus, with the overlying tibialis posterior (TP) and FDL
tendons. (C) Relevant anatomy and probe placement.

A

B

C

Figure 5-25. Tibiocalcaneal ligament. (A) Probe placement with the ankle
in dorsiflexion. (B) Tibiocalcaneal ligament (white arrows) between the tibia
and the sustentaculum tali (ST). (C) Relevant anatomy and probe placement.

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B

C

Figure 5-26. Tibiospring ligament. (A) Probe placement with the ankle in
dorsiflexion. (B) Tibiospring ligament (white arrows) between the tibia and
the spring ligament (SP). (C) Relevant anatomy and probe placement.

A

B

C
Figure 5-27. Tibionavicular ligament. (A) Probe placement with the ankle in
plantar flexion. (B) Tibionavicular ligament (white arrows) between the tibia
and the navicular bone (N). (C) Relevant anatomy and probe placement.

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A

135

B

C

Figure 5-28. Anterior tibiotalar ligament. (A) Probe placement with the ankle
in plantar flexion. (B) Anterior tibiotalar ligament (white arrows) between the
tibia and the talus. (C) Relevant anatomy and probe placement.

A

B

C

Figure 5-29. Medial talocalcaneal ligament. (A) Probe placement with
the ankle in dorsiflexion. (B) Medial talocalcaneal ligament (white arrows)
between the sustentaculum tali (ST) and the medial tubercle of the talus (T).
(C) Relevant anatomy and probe placement.

2. Probe/transducer position: The probe is placed along the ligament scanned in the LX, keeping
one end of the probe fixed at the medial malleolus and moving the other end of the probe in a
fan-shape movement from the talus to the sustentaculum tali of the calcaneus, the superomedial
portion of the spring ligament, the dorsomedial aspect of the navicular bone, and the anteromedial aspect of the talus to scan the medial collateral complex (see Figures 5-24 through 5-29).
3. Relevant anatomy: The deep layer is much stronger than the superficial layer. The entire medial collateral ligament complex acts like a unit to stabilize the ankle and resist eversion. There
is an interlacing of the fibers of the tibionavicular, tibiospring, and spring ligament complex.

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4. Points to remember: An isolated tear of the deltoid ligament is rare. A deltoid ligament tear is
usually associated with other injuries of the ankle, such as a lateral malleolus fracture, or a
less common injury, such as an avulsion fracture of the medial malleolus. The tibionavicular
ligament is present in 55% of the population. The tibiocalcaneal ligament is present in 88% of
the population.2 The anterior tibiotalar ligament is a very thin ligament, and its absence can
be attributed to normal anatomical variation. The posterior tibiotalar ligament is the thickest
ligament of the medial collateral ligament complex.2
The tibiotalar ligament complex may appear hypoechoic on ultrasound due to fiber orientation and interspersed fat between the tendon fascicles. The tibiocalcaneal band appears as a
thin band with the posterior tibialis tendon overlying it.

POSTERIOR ANKLE
Achilles Tendon
1. Patient position: Prone with foot over the edge of the table
2. Probe/transducer position:
a. LX view: The probe is placed along the Achilles tendon, with the calcaneus bone in view.
The Achilles tendon is scanned from the bony insertion site at the calcaneus to the muscletendon junction proximally (Figures 5-30 and 5-31).
b. SX view: The probe is placed transversely across the Achilles tendon, which is scanned in
an inferior-to-superior direction to visualize the entire tendon (Figure 5-32).
A

B

Figure 5-30. LX view of the Achilles tendon. (A) Probe placement. (B) LX view of the
Achilles tendon showing Kager’s fat pad (white star).

Figure 5-31. Panoramic LX view of the Achilles tendon from the calcaneal insertion to the myotendinous area showing
the hyperechoic Kager’s fat pad (white star).

Ankle and Foot

Figure 5-32. SX view of the Achilles tendon at different levels from distal to proximal.

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3. Relevant anatomy: The calcaneal tuberosity has 3 facets: superior, middle, and inferior
(Figure 5-33). The retrocalcaneal bursa overlies the superior facet. The middle facet is divided
into 2 parts: The fascicles of the lateral head of the gastrocnemius tendon attach on the lateral
aspect of the middle facet, and the fascicles of the soleus tendon attach to the medial aspect of
the middle facet. The fascicles of the medial head of the gastrocnemius attach on the inferior
facet (Figure 5-34).6

Figure 5-33. Facets of the calcaneal tuberosity.

A

B

Figure 5-34. (A) Facets of the calcaneal tuberosity. (B) LX view of the Achilles
tendon showing the superior (S), middle (M), and inferior (I) facets.

Kager’s fat pad is a triangular region made up of the Achilles tendon, flexor hallucis tendon,
and a wedge of fat adjacent to the calcaneus bone.7

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139

4. Points to remember: The most superficial part of the Achilles tendon is formed by the medial
gastrocnemius, which inserts on the entire width of the calcaneal tuberosity.
It has been reported that the Achilles tendon may be continuous with the plantar fascia via
the paratenon (Figure 5-35).6,8

A

B

Figure 5-35. (A) Probe placement. (B) Achilles tendon (big white arrow) continuous with the plantar fascia (yellow
arrow) via the paratenon (small white arrows).

The plantaris tendon is absent in 6% to 8% of the population.9 When present, the plantaris
tendon attaches to the middle facet on the medial aspect. There are variations in the plantaris
tendon insertion footprint reported in the literature.10
During plantar flexion, Kager’s fat pad extends into the retrocalcaneal bursa as far as the
enthesis. In neutral position, Kager’s fat pad gets retracted so that the tendon is against the
bone (the superior tuberosity of the calcaneus).7

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Posterior Inferior Tibiofibular Ligament
Relevant anatomy is shown in Figure 5-36.

Figure 5-36. Relevant anatomy of the posterior ligaments of the ankle.

1. Patient position: Ankle in slight dorsiflexion and eversion
2. Probe/transducer position: The probe is placed along the ligament, bridging the distal tibia and
fibula posteriorly (Figure 5-37).

A

B

Figure 5-37. Posterior tibiofibular ligament. (A) Probe placement with the ankle in dorsiflexion and eversion. (B) Posterior tibiofibular
ligament (white arrow) between the tibia and the fibula (lateral malleolus).

3. Relevant anatomy: The ligament is obliquely oriented from the posterior tubercle of the tibial
shaft to the posterior aspect of the lateral malleolus.
4. Points to remember: The posterior inferior tibiofibular ligament is much stronger than the
anterior inferior tibiofibular ligament and is rarely involved in ankle sprains.

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Posterior Talofibular Ligament
1. Patient position: Ankle in slight dorsiflexion
2. Probe/transducer position: The probe is placed along the ligament, bridging the talus and
fibula posteriorly (Figure 5-38).

A

B

Figure 5-38. Posterior talofibular ligament. (A) Probe placement with the ankle in dorsiflexion. (B) Posterior
talofibular ligament (white arrows) between the talus and fibula (Fib; lateral malleolus).

3. Relevant anatomy: The ligament connects the lateral tubercle of the posterior process of the
talus to the posterior aspect of the lateral malleolus. The ligament is intracapsular but extrasynovial. It is the deepest ligament of the lateral collateral complex. The primary function of
the ligament is to restrain the posterior displacement of the talus.
4. Points to remember: Full dorsiflexion puts the ligament under the greatest strain. The posterior talofibular ligament is rarely involved in ankle sprains because the bony stability protects
the ligament in dorsiflexion. Due to its deep location, there is a limited window to scan the
ligament, and the ligament can only be partially visualized.

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HINDFOOT
Subtalar Joint
The subtalar joint is divided into the anterior subtalar joint (ASTJ) and posterior subtalar joint
(PSTJ). There is lack of communication between the ASTJ and PSTJ; therefore, the anterior and
posterior joints should be evaluated separately (Figure 5-39).11

Figure 5-39. Relevant anatomy of the subtalar joint.

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Anterior Subtalar Joint (Medial Approach)
1. Patient position: Supine with the leg externally rotated to examine the medial aspect of the foot
2. Probe/transducer position: The probe is placed to bridge the medial malleolus and distal pole
of the sustentaculum tali. While keeping the distal part of the probe fixed on the sustentaculum tali, the proximal part of the probe is rotated anteriorly toward the navicular bone until
the ASTJ is visualized (Figure 5-40).11

A

B

Figure 5-40. ASTJ (medial approach). (A) Probe placement between the sustentaculum tali and the navicular bone. (B)
ASTJ (white arrow). (N = navicular bone; ST = sustentaculum tali.)

3. Relevant anatomy: The spring ligament overlying the talar cartilage is visualized at this level.
Overlying the spring ligament is the oblique SX view of the tibialis posterior tendon.
4. Points to remember: The sustentaculum tali is an important bony landmark and needs to be
correctly identified to scan the ASTJ.

Posterior Subtalar Joint (Medial Approach)
1. Patient position: Supine with the leg externally rotated to examine the medial aspect of the foot
2. Probe/transducer position: Initially the probe is placed in the LX to bridge the medial malleolus and distal pole of the sustentaculum tali. The probe is then moved posterior to the medial
malleolus in the same orientation to scan the FHL tendon in the LX view. The PSTJ is visualized underneath the FHL tendon (Figure 5-41).11

A

B

Figure 5-41. PSTJ (medial approach). (A) Probe placement posterior to the
medial malleolus to visualize the FHL tendon. The subtalar joint is seen
underneath the FHL tendon. (B) Subtalar joint (white arrow) and overlying FHL tendon. The posterior tibiotalar joint
(white triangle) can be seen proximally.

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3. Relevant anatomy: The tibiotalar joint is immediately proximal to the PSTJ in the view.
4. Points to remember: There is communication between PSTJ and the posterior recess of the
tibiotalar joint (ankle joint).

Posterior Subtalar Joint (Lateral Approach)
1. Patient position: Supine with the leg internally rotated to examine the lateral aspect of the foot
or side-lying with the foot to be examined on the top to access the lateral aspect of the foot
2. Probe/transducer position: Initially the probe is placed in the LX to bridge the tip of the lateral
malleolus and lateral calcaneal surface. The probe is then moved slightly anterior to the lateral
malleolus in the same orientation to scan the PSTJ, visualizing 3 bony landmarks: calcaneus,
talus, and distal end of the fibula (lateral malleolus; Figure 5-42).11

A

B

Figure 5-42. PSTJ (lateral approach). (A) Probe placement anterior to the lateral malleolus in the LX orientation,
bridging the lateral malleolus, talus, and calcaneus. (B) Subtalar joint (white arrow).

3. Relevant anatomy: Three bony landmarks are the calcaneus, talus, and fibula (lateral malleolus). The PSTJ is between the calcaneus and talus. The peroneus longus and brevis are visualized overlying the bony landmarks.
4. Points to remember: There is communication between the PSTJ and the posterior recess of the
tibiotalar joint (ankle joint).

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Posterior Subtalar Joint (Posterior Approach)
1. Patient position: Side-lying with the foot to be examined on the top to scan the posterior aspect
or lying prone to examine the posterior aspect; ankle in neutral or slightly dorsiflexed
2. Probe/transducer position: The probe is placed along the LX of the Achilles tendon with the
distal end of the probe on the calcaneus bone. The depth of the scan is increased to visualize
the PSTJ, deep to Kager’s fat pad (Figure 5-43).11

A

B

Figure 5-43. PSTJ (posterior approach). (A) Probe placement along the LX of the Achilles tendon. The depth of the
scan is increased to visualize the PSTJ, deep to Kager’s fat pad. (B) PSTJ (white arrow). (Ach = Achilles tendon.)

3. Relevant anatomy: Three bony landmarks are the distal tibia, talus, and calcaneus. The
Achilles tendon and Kager’s fat pad overlie the PSTJ.
4. Points to remember: Adding dorsiflexion helps visualize the PSTJ better.

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Plantar Fascia
Relevant anatomy is shown in Figures 5-44 and 5-45.

Figure 5-44. Relevant anatomy of the plantar fascia.

Figure 5-45. Relevant anatomy of the lateral cord of the plantar fascia and other attachments at the fifth metatarsal
(MT) base.

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147

1. Patient position: Prone with the foot to be examined over the edge of the table
2. Probe/transducer position: The probe is placed along the LX of the plantar fascia with the
proximal end of the probe on the medial calcaneal tuberosity to scan the central cord (Figures
5-46 and 5-47). For the lateral cord, the probe is moved laterally toward the fifth metatarsal
(Figure 5-48).

A

B

C

Figure 5-46. Central cord of the
plantar fascia. (A) Probe placement.
(B) LX view of the central cord of the
plantar fascia (white arrow). (C) SX view
of the central cord of the plantar fascia
(white arrow).

Figure 5-47. Panoramic view of the
central cord of the plantar fascia
(white arrows).

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A

Figure 5-48. (A) Lateral cord of the plantar fascia (white
arrows) between the calcaneus and the tuberosity of the
fifth metatarsal (MT). (B) Relevant anatomy and probe
placement.

B

3. Relevant anatomy: There are 2 cords of the plantar fascia that originate from the medial calcaneal tuberosity: central cord and lateral cord. The central cord continues distally and divides
into 5 fascicles to attach to the plantar plate of each toe. The lateral cord of the plantar fascia
changes its course from plantigrade orientation to sagittal orientation as it attaches to the
lateral aspect of the fifth metatarsal tuberosity.12,13
4. Points to remember: The lateral cord of plantar fascia enthesopathy at the fifth metatarsal
tuberosity may be suspected in nontraumatic foot pain arising from the fifth metatarsal base.12

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MIDFOOT
Lateral Ligaments
The dorsal calcaneocuboid ligament and dorsal talonavicular ligament are shown in Figure 5-7.
1. Patient position: Foot in slight inversion for the calcaneocuboid ligament; foot in plantar flexion for the dorsal talonavicular ligament
2. Probe/transducer position:
a. Dorsal calcaneocuboid ligament: The distal end of probe is placed over the base of the
fifth metatarsal, which is an initial bony landmark, then the probe is moved proximally to
visualize the calcaneocuboid joint (Figure 5-49).

A

C

B

Figure 5-49. Dorsal calcaneocuboid ligament. (A) Probe placement with
the foot in slight inversion. The distal end of the probe is placed over the
base of the fifth metatarsal, which is the initial bony landmark, then the
probe is moved proximally to visualize the calcaneocuboid joint. (B) Dorsal
calcaneocuboid ligament (white arrows) between the calcaneus and the
cuboid bone. (C) Relevant anatomy and probe placement.

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b. Dorsal talonavicular ligament: Initially the probe is placed along the LX of the anterior tibiotalar joint recess, and then the probe is moved distally until the neck of the talus is visualized as the ligament spans from the neck of the talus to the navicular bone (Figure 5-50).2

A

C

B

Figure 5-50. Dorsal talonavicular ligament. (A) Probe placement along the
LX of the anterior tibiotalar joint recess. The probe is then moved distally
until the neck of the talus is visualized as the ligament spans from the neck
of the talus to the navicular bone. (B) Dorsal talonavicular ligament (white
arrows) between the talus and the navicular bone. (C) Relevant anatomy and
probe placement.

3. Relevant anatomy: The dorsal calcaneocuboid ligament is the thickening of the dorsolateral
aspect of the capsule of the calcaneocuboid joint. The dorsal talonavicular ligament blends
with the capsule of the talonavicular joint and is covered by the extensor tendons.2
4. Points to remember: The dorsal talonavicular ligament is not parallel to the skin; therefore,
slight distal tilt is required to avoid anisotropy.

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Medial Ligaments
The plantar calcaneonavicular ligament or spring ligament complex includes 3 parts: superomedial, medioplantar oblique, and inferoplantar longitudinal (see Figure 5-23).
1. Patient position: Foot in neutral to slight dorsiflexion
2. Probe/transducer position: The superomedial portion is scanned by placing one end of the
probe on the sustentaculum tali and the other end on the superomedial aspect of the navicular
bone (Figure 5-51).

A

B

C

Figure 5-51. Spring ligament, or plantar calcaneonavicular ligament. (A)
Probe placement between the sustentaculum tali and the superomedial
aspect of the navicular bone. (B) Plantar calcaneonavicular ligament (white
arrows) between the sustentaculum tali (ST) and the navicular bone (N).
(C) Relevant anatomy and probe placement.

The medioplantar oblique and inferoplantar longitudinal components of the spring ligament complex are deep and therefore difficult to visualize. Dynamic evaluation with valgus
stress may be used to check the medioplantar and inferoplantar portions for their intactness.2
3. Relevant anatomy: The superomedial portion of the spring ligament appears as a hyperechoic
band. The overlying posterior tibialis tendon can be visualized.2
4. Points to remember: The spring ligament complex is a major stabilizer of the plantar arch. Due
to its close proximity to the posterior tibialis tendon, injury or dysfunction is closely related to
posterior tibialis tendon dysfunction, and vice versa.

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FOREFOOT
Metatarsophalangeal Joint and Plantar Plate
Relevant anatomy is shown in Figure 5-52.

Figure 5-52. Relevant anatomy of the metatarsophalangeal (MTP) joint and plantar plate region.

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153

1. Patient position: Supine with the foot in neutral position
2. Probe/transducer position:
a. Plantar aspect: The probe is placed in the LX along the plantar aspect of the MTP joint. The
probe is placed transversely for the SX view (Figures 5-53 through 5-55).
A

B

Figure 5-53. LX view of the first MTP joint on the plantar aspect. (A) Probe placement. (B) FHL tendon (white arrows)
and hyperechoic plantar plate (yellow arrow) overlying the MTP region.

A

B

Figure 5-54. SX view of the first MTP joint on the plantar aspect. (A) Probe placement. (B) FHL tendon (white arrow)
between 2 sesamoid bones (SB). Also shown is the intersesamoid ligament (blue arrow).

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A

B

Figure 5-55. LX view of the second MTP joint on the plantar aspect. (A) Probe placement. (B) Flexor tendons (white
arrows) and hyperechoic plantar plate (between the yellow arrows) overlying the MTP region.

b. Dorsal aspect: The probe is placed in the LX along the dorsal aspect of the MTP joint
(Figure 5-56). The probe is placed transversely for the SX view.

A

B

Figure 5-56. LX view of the first MTP joint on the dorsal aspect. (A) Probe placement. (B) MTP joint and overlying
extensor tendon (white arrows).

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3. Relevant anatomy:
a. First MTP: There are 2 sesamoid bones present on the plantar aspect of the first MTP joint
held together by ligaments. Between the 2 sesamoid bones is the small window to visualize
the plantar plate region, which lies deep to the intersesamoid ligament and just above the
MTP joint articulation. The FHL runs above the intersesamoid ligament to insert distally
at the base of the distal phalanx.14,15
b. Lesser MTP joints: In the lesser MTP joints, 2 tendons overlie the plantar plate region: the
FDL and the flexor digitorum brevis (FDB). The FDB divides into 2 slips distally to attach
on either side of the proximal phalanx. The FDL attaches distally at the base of the distal
phalanx (see Figure 5-55).15,16
4. Points to remember: The plantar plates act as a primary stabilizer of the MTP joint and are
formed by the fiber contribution from multiple structures blending together, such as the flexor
hallucis tendon, deep intermetatarsal ligament, distal margin of the intersesamoid ligament,
plantar fascia, and aponeurotic fibers of the extensor hood. In the lesser MTP joints, the plantar plate consists of fibrocartilage and type I collagen.16,17

Intermetatarsal Space
Relevant anatomy is shown in Figure 5-57.

Figure 5-57. Relevant anatomy of the intermetatarsal space. (EDB = extensor digitorum brevis; M = metatarsal.)

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1. Patient position: Supine with the foot in neutral position
2. Probe/transducer position: The probe is placed transversely at the level of the metatarsal heads
on the plantar aspect for plantar examination or the dorsal aspect for dorsal examination
(Figures 5-58 and 5-59).

A

Figure 5-58. Intermetatarsal space
on the plantar aspect. (A) Probe
placement with relevant anatomy. (B)
Intermetatarsal space on the plantar
aspect showing the FHL (yellow arrow),
FDB (white arrow), FDL (red arrow),
artery (red triangle), digital nerve
(yellow triangle), and sesamoid bone
(SB). (M = metatarsal.) (C) Color Doppler
image showing an artery (red triangle)
and nerve (yellow triangle).

B

C

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157

A

B

Figure 5-59. Intermetatarsal space
on the dorsal aspect. (A) Probe
placement with relevant anatomy.
(B) Intermetatarsal space on the
dorsal aspect showing the extensor
digitorum brevis (blue arrow), EDL
(red arrow), EHL (white arrow), digital
nerve (yellow arrow), artery (white A),
and dorsal interosseous muscle (DI).
(M = metatarsal.)

3. Relevant anatomy: The intermetatarsal space on the dorsal aspect contains the neurovascular
bundle, dorsal interosseous muscle, plantar interosseous muscle, and intermetatarsal bursa. On
the plantar space, the neurovascular bundle and lumbrical muscle occupy the intermetatarsal
space.18
4. Points to remember: Intermetatarsal bursal effusion and bursitis can present similar to Morton
neuroma. Evaluation of the intermetatarsal space can be performed by placing the probe on
the dorsal or plantar aspect with one of the examiner’s fingers providing counterpressure
toward the probe from the opposite aspect of the metatarsal space. This procedure will help
differentiate fluid (bursal effusion) from a solid mass, as in neuroma.19

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Chapter 5

REFERENCES
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.

14.
15.
16.
17.
18.
19.

Ng JM, Rosenberg ZS, Bencardino JT, Restrepo-Velez Z, Ciavarra GA, Adler RS. US and MR imaging of the
extensor compartment of the ankle. Radiographics. 2013;33(7):2047-2064.
Sconfienza LM, Orlandi D, Lacelli F, Serafini G, Silvestri E. Dynamic high-resolution US of ankle and midfoot
ligaments: normal anatomic structure and imaging technique. Radiographics. 2015;35(1):164-178.
Hermans JJ, Beumer A, de Jong TA, Kleinrensink GJ. Anatomy of the distal tibiofibular syndesmosis in adults:
a pictorial essay with a multimodality approach. J Anat. 2010;217(6):633-645.
Golano P, Vega J, de Leeuw PA, et al. Anatomy of the ankle ligaments: a pictorial essay. Knee Surg Sports
Traumatol Arthrosc. 2010;18(5):557-569.
Bilgili MG, Kaynak G, Botanlioglu H, et al. Peroneus quartus: prevalence and clinical importance. Arch Orthop
Trauma Surg. 2014;134(4):481-487.
Ballal MS, Walker CR, Molloy AP. The anatomical footprint of the Achilles tendon: a cadaveric study. Bone
Joint J. 2014;96-B(10):1344-1348.
Theobald P, Bydder G, Dent C, Nokes L, Pugh N, Benjamin M. The functional anatomy of Kager’s fat pad in
relation to retrocalcaneal problems and other hindfoot disorders. J Anat. 2006;208(1):91-97.
Stecco C, Corradin M, Macchi V, et al. Plantar fascia anatomy and its relationship with Achilles tendon and
paratenon. J Anat. 2013;223(6):665-676.
Dalmau-Pastor M, Fargues-Polo B Jr, Casanova-Martinez D Jr, Vega J, Golanó P. Anatomy of the triceps surae:
a pictorial essay. Foot Ankle Clin. 2014;19(4):603-635.
Olewnik L, Wysiadecki G, Polguj M, Topol M. Anatomic study suggests that the morphology of the plantaris
tendon may be related to Achilles tendonitis. Surg Radiol Anat. 2017;39(1):69-75.
Mandl P, Bong D, Balint PV, et al. Sonographic and anatomic description of the subtalar joint. Ultrasound Med
Biol. 2018;44(1):119-123.
Hoffman DF, Nazarian LN, Smith J. Enthesopathy of the lateral cord of the plantar fascia. J Ultrasound Med.
2014;33(9):1711-1716.
Moraes do Carmo CC, Fonseca de Almeida Melão LI, Valle de Lemos Weber MF, Trudell D, Resnick D.
Anatomical features of plantar aponeurosis: cadaveric study using ultrasonography and magnetic resonance
imaging. Skeletal Radiol. 2008;37(10):929-935.
Nery C, Fonseca LF, Gonçalves JP, et al. First MTP joint instability—expanding the concept of “turf-toe” injuries. Foot Ankle Surg. 2020;26(1):47-53.
Nery C, Baumfeld D, Umans H, Yamada AF. MR imaging of the plantar plate: normal anatomy, turf toe, and
other injuries. Magn Reson Imaging Clin N Am. 2017;25(1):127-144.
Finney FT, Cata E, Holmes JR, Talusan PG. Anatomy and physiology of the lesser metatarsophalangeal joints.
Foot Ankle Clin. 2018;23(1):1-7.
Stone M, Eyler W, Rhodenizer J, van Holsbeeck M. Accuracy of sonography in plantar plate tears in cadavers.
J Ultrasound Med. 2017;36(7):1355-1361.
Theumann NH, Pfirrmann CW, Chung CB, et al. Intermetatarsal spaces: analysis with MR bursography, anatomic correlation, and histopathology in cadavers. Radiology. 2001;221(2):478-484.
Bianchi S. Practical US of the forefoot. J Ultrasound. 2014;17(2):151-164.

6
Knee
Mohini Rawat, DPT, MS, ECS, OCS, RMSK

Contents
• Anterior Knee
º Suprapatellar Region
º Quadriceps Tendon
º Femoral Trochlear Cartilage
º Patellar Tendon
º Anterior Bursae
º Medial and Lateral Patellar Retinaculum
• Medial Knee
º Medial Joint and Meniscus
º Medial Collateral Ligament, Posterior Oblique Ligament, Adductor Magnus Tendon, and
Medial Patellofemoral Ligament
º Pes Anserine Tendons
• Lateral Knee
º Lateral Joint and Meniscus
º Popliteus Tendon
º Lateral Collateral Ligament
º Iliotibial Band
º Biceps Femoris Tendon
º Common Fibular Nerve
• Posterior Knee
º Joint Anatomy
º Semimembranosus Muscle-Tendon Complex
º Tibial Nerve and Blood Vessels
- 159 -

Rawat M.
Atlas of Musculoskeletal Ultrasound of the Extremities (pp 159-199).
© 2021 SLACK Incorporated.

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ANTERIOR KNEE
Suprapatellar Region
1. Patient position: Supine with the knee flexed at 30 degrees and supported on a roll/pillow
2. Probe/transducer position:
a. Long axis (LX) view/longitudinal view: Use the patella as a bony landmark to scan the
region in the LX view (Figure 6-1).

A

C

B

Figure 6-1. LX view of the suprapatellar
region. (A) Limb positioning: supine
with the knee flexed at 30 degrees and supported on a roll/pillow. (B) Probe placement. (C) LX view of the suprapatellar
region showing the quadriceps tendon (big white arrow) and the suprapatellar fat pad (thin white arrow) separated
from the prefemoral fat pad (yellow arrow) by the thin hypoechoic capsule.

b. Short axis (SX) view/transverse view: Place the probe transversely across the quadriceps
tendon just proximal to its attachment at the patella to visualize the distal portion of the
tendon in the SX view (Figure 6-2).

A

Figure 6-2. SX view of the suprapatellar
region. (A) Probe placement. (B) SX view
of the suprapatellar region showing the
quadriceps tendon (big white arrow)
and fat pad (thin white arrow) above
the femur.

B

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3. Relevant anatomy: From superficial to deep, structures are visualized as skin, subcutaneous
layer, quadriceps tendon attaching to the patella, prefemoral fat pad and suprapatellar fat pad,
and femoral bony interface as the deepest structure (Figure 6-3).

Figure 6-3. Sagittal section of the knee showing relevant anatomy of the suprapatellar region.

4. Points to remember: Knee flexion at approximately 30 degrees is the optimal position to visualize the anatomy of the suprapatellar region to minimize anisotropy artifact due to tendon slack.

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Quadriceps Tendon
1. Patient position: Same as the position for a suprapatellar scan, with added flexion to take out
the tendon slack if tendons show anisotropy artifact
2. Probe/transducer position: Same as for a suprapatellar scan
3. Relevant anatomy: When scanned in the LX view, the quadriceps tendon shows a multilayer
arrangement. From superficial to deep, there are 3 layers: the rectus femoris, vastus medialis/
lateralis, and vastus intermedius (Figures 6-4 through 6-7).

A

B

Figure 6-4. LX view of the quadriceps
tendon. (A) Probe placement. (B) LX
view of the quadriceps tendon showing
the multilayer arrangement of the
rectus femoris (white triangle), vastus
lateralis/medialis (red triangle), and
vastus intermedius (yellow triangle).

A

Figure 6-5. SX view of the quadriceps
tendon. (A) Probe placement. (B) SX
view of the quadriceps tendon showing
the rectus femoris (white arrow) on top,
vastus lateralis (VL) and vastus medialis
(VM) in the middle (red arrow), and
vastus intermedius (yellow arrow) as
the deep layer.

B

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Figure 6-6. Panoramic LX view of the quadriceps (white arrow).

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Chapter 6

Figure 6-7. Panoramic SX view of the quadriceps muscle showing the rectus femoris (white arrow), vastus lateralis (VL)
and vastus medialis (VM; red arrows), and vastus intermedius (yellow arrow).

4. Points to remember: A slack tendon may appear hypoechoic due to anisotropy. It is important
to scan the tendon in a stretched position so that the ultrasound beam strikes the tendon at 90
degrees for optimal scanning. Too much stretch should be avoided because it can obliterate the
small blood vessels in cases of neoangiogenesis and color Doppler may not show hyperemia or
positive color Doppler sign.

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165

Femoral Trochlear Cartilage
1. Patient position: Supine with maximum knee flexion
2. Probe/transducer position:
a. LX view/longitudinal view: With the patella as a bony landmark, the probe is oriented
along the quadriceps tendon in the LX view (Figure 6-8).

A

C

Figure 6-8. Femoral trochlear cartilage. (A) Limb positioning: supine with
maximum knee flexion. (B) Probe placement for the LX view. (C) Femoral
trochlear cartilage (white arrow) is seen as an anechoic structure over the
femoral bony interface.

B

b. SX view/transverse view: Place the probe transversely at the level just proximal to the superior border of the patella to visualize the femoral trochlear cartilage (Figure 6-9).

A

Figure 6-9. Sunrise view of the
femoral trochlear cartilage. (A) Probe
placement for sunrise view. (B) Sunrise
view showing the anechoic cartilage
overlying the femoral bony interface.

B

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3. Relevant anatomy: In the SX view, the femoral trochlear cartilage appears as an anechoic
uniform area following the bony contour of the femoral trochlea. A sharp bony edge/protuberance on the medial aspect is the normal finding. Anechoic cartilage can also be seen in
the LX view.
4. Points to remember: Adding maximum flexion to the knee exposes the femoral trochlear cartilage anteriorly for sonographic visualization. If there is range of motion limitation of knee
flexion, the femoral trochlear cartilage view may be restricted.

Patellar Tendon
1. Patient position: Supine with 30-degree knee flexion
2. Probe/transducer position:
a. LX view/longitudinal view: Scan the patellar tendon longitudinally by bridging the patella
and tibial tuberosity (Figure 6-10).

A

B

Figure 6-10. LX view of the patellar tendon. (A) Probe placement. (B) LX view of the patellar tendon.

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167

b. SX view/transverse view: Place the probe transversely across the patellar tendon. The tendon should be scanned along the length of the tendon in the SX view for complete evaluation (Figure 6-11).

A

Figure 6-11. SX view of the patellar
tendon. (A) Probe placement. (B) SX
view of the patellar tendon (white
arrow) at mid-length. (C) SX view of the
patellar tendon (white arrow) distally
over the tibia.

B

C

3. Relevant anatomy: There is a proximal bony attachment of the patellar tendon at the patella
and a distal tendon attachment at the tibial tuberosity. From superficial to deep, the structures
are visualized as skin, subcutaneous tissue, patellar tendon attaching proximally to the patella
and distally to the tibial tuberosity, and fat pad/Hoffa’s fat pad.
4. Points to remember: The patellar tendon should be scanned in the LX and SX views from its
proximal attachment site at the patella to the distal attachment site at the tibial tuberosity
(Figure 6-12).
Figure 6-12. Panoramic LX view of
the patellar tendon (white arrows).

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Anterior Bursae
1. Patient position: Supine with slight knee flexion
2. Probe/transducer position:
a. LX view/longitudinal view: The probe is placed longitudinally over the patella and
then moved distally over the patellar tendon and tibial tuberosity with light pressure
(Figure 6-13).

A

B

Figure 6-13. Anterior bursae. (A) Probe placement. (B) LX view of the anterior knee with light pressure to evaluate the
subcutaneous bursae.

b. SX view/transverse view: The SX view is only used to confirm abnormal findings in the
LX view.

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3. Relevant anatomy: There are 2 subcutaneous bursae on the anterior aspect of the knee: the
prepatellar bursa, which is just above the patella, and the superficial infrapatellar bursa, which
is just superficial to the distal patellar tendon and tibial tuberosity. There is a deep bursa called
the deep infrapatellar bursa, which is present between the distal patellar tendon and the tibia
(Figures 6-14 through 6-16).1

Figure 6-14. Relevant anatomy of the anterior bursae and fascial layers.

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Figure 6-15. LX view of the anterior fascial layers over the quadriceps and patella showing the tendon layer (white
arrows), oblique fascia (blue arrow), and superficial fascia (pink arrow). (Q = quadriceps tendon.)

A

B

Figure 6-16. (A) LX view over the patellar tendon showing the location of the deep
infrapatellar bursa (white arrow). There is minimal fluid. (B) Same view with increased probe
pressure causing disappearance of the minimal fluid seen before.

4. Points to remember: Lots of gel and very light transducer pressure is required to scan these
subcutaneous bursae because increased pressure will force the fluid away from the probe, and
therefore, bursal fluid may not be visualized. In a normal state, these bursae are not visible.
An anatomic variant of the bipartite or tripartite patellae may be present, which can be
confused with a fracture or breach in the continuity of the bony surface of the patella. This
anatomic variant is caused by nonunion of an accessory ossification center of the patella.
Misinterpretation can be avoided with thorough history taking, clinical correlation, and, in
some cases, follow-up radiographs.
Hoffa’s fat pad should not be confused with deep infrapatellar bursal effusion because the
fat pad between the distal patellar tendon and the tibia can sometimes appear hypoechoic.
Any abnormal signal should be confirmed in the SX view. Deep infrapatellar bursal effusion,
when present, is accompanied with posterior enhancement artifact.

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Medial and Lateral Patellar Retinaculum
1. Patient position: Supine with the knee extended and resting on the table
2. Probe/transducer position: The probe is placed along the medial retinaculum bridging the
patella and the medial femoral condyle (Figure 6-17). For the lateral retinaculum, the probe
is placed along the lateral retinaculum bridging the patella and the lateral femoral condyle
(Figure 6-18).

A

B

Figure 6-17. Medial retinaculum. (A) Probe placement. (B) Medial retinaculum (white arrows) as a bilaminar structure.

A

B

Figure 6-18. Lateral retinaculum. (A) Probe placement. (B) Lateral retinaculum (white arrows) as a bilaminar structure.

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3. Relevant anatomy: The patellar retinaculum appears as a bilaminar structure that stabilizes the
patella in the transverse plane (Figure 6-19). With the knee extended, the medial patellar facet
can be seen by pushing the patellar medially from the lateral edge. The medial patellar retinaculum is longer and laxer than the lateral patellar retinaculum, which allows the visualization of
the medial patellar facet by pushing the patella medially from the lateral edge of the bone (Figure
6-20). The lateral patellar facet cannot be visualized by pushing the medial edge laterally.

Figure 6-19. Relevant anatomy of the patellar retinaculum. (ITB = iliotibial band; LCL = lateral collateral ligament;
MCL = medial collateral ligament.)

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A

173

B

Figure 6-20. Medial patellar facet. (A)
Initial probe placement is similar to
medial retinaculum scanning. After
pushing the patella medially, the probe
is hooked under the patella so that the
beam is directed toward the medial
patellar facet. (B) Cartilage-lined medial patellar facet (red arrow) and overlying retinaculum (white arrow).

4. Points to remember: It is important to remember when placing the probe along the patellar
retinaculum that the orientation of the probe is along the fiber length and not in SX/transverse
orientation with respect to the knee.

MEDIAL KNEE
Medial Joint and Meniscus
1. Patient position: Supine with the leg externally rotated and the knee flexed approximately 30
degrees with a pillow or roll on the lateral aspect of the knee for slight valgus stress
2. Probe/transducer position: For the LX view of the medial joint space, the probe is placed longitudinally to bridge the femur and tibia (Figure 6-21).

A

B

Figure 6-21. Medial meniscus. (A) Probe placement. (B) Medial meniscus (white arrow) as a triangular hyperechoic
structure.

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Chapter 6

3. Relevant anatomy: The medial meniscus in the medial joint space appears as a hyperechoic
triangular structure (Figure 6-22).

Figure 6-22. Relevant anatomy of the medial joint. (ACL = anterior cruciate ligament; dMCL = deep medial collateral
ligament; PCL = posterior cruciate ligament; sMCL = superficial medial collateral ligament.)

4. Points to remember: Ultrasound provides a limited view of the medial meniscus and therefore
cannot assess the extent of meniscal pathology. Other imaging modalities, such as magnetic
resonance imaging (MRI), are preferred when meniscal pathology is in question.

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175

Medial Collateral Ligament, Posterior Oblique Ligament,
Adductor Magnus Tendon, and Medial Patellofemoral Ligament
1. Patient position: Supine with the leg externally rotated and the knee flexed approximately 30
degrees with a pillow or roll on the lateral aspect of the knee for slight valgus stress
2. Probe/transducer position: The probe is placed in the LX along the MCL (Figures 6-23 and
6-24).

A

B

Figure 6-23. MCL. (A) Probe placement. (B) LX view of the MCL (white arrows).

Figure 6-24. Panoramic view of the MCL (white arrows). The darker area over the distal part of the MCL is the pes
anserine tendons (red arrows) in the oblique SX view.

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Chapter 6

3. Relevant anatomy: The MCL is a bilaminar structure composed of the dMCL and the sMCL
(see Figure 6-22). The dMCL can be divided into the meniscofemoral and meniscotibial ligaments. The dMCL blends with the medial meniscus. The footprint of the sMCL at the femoral insertional area is about 3 cm from the medial joint line, and the footprint at the tibial
insertional area is about 6.3 cm from the medial joint line. The footprint of the dMCL at the
femoral insertional area is about 2 cm from the joint line, and the footprint of the dMCL at
the tibial insertional area is about 0.7 cm from the joint line.2,3 The posterior oblique ligament (POL) attachment is just posterior to the sMCL attachment at the femur (Figures 6-25
through 6-27).

Figure 6-25. Relevant anatomy and footprint of the MCL. The footprint of the sMCL at the femoral insertional area is
about 3 cm from the medial joint line, and the footprint at the tibial insertional area is about 6.3 cm from the medial
joint line. The footprint of the dMCL at the femoral insertional area is about 2 cm from the joint line, and the footprint
of the tibial insertional area is about 0.7 cm from the joint line.2,3 The POL attachment is just posterior to the sMCL
attachment at the femur.

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177

Figure 6-26. Meniscofemoral (yellow arrows) and meniscotibial (red arrows) portions of the dMCL.

Figure 6-27. Relevant anatomy of the medial knee ligaments and tendons. (MPFL = medial patellofemoral ligament.)

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Chapter 6

4. Points to remember: The MCL is wider at the joint level, and the posterior portion of the sMCL
blends with the medial meniscus.2 The MCL is tight at 30 degrees of flexion, and the POL is
tight in extension. The POL, adductor magnus tendon, and medial patellofemoral ligament
can be scanned medially (Figures 6-28 through 6-31).

A

B

C

Figure 6-28. POL. (A) Relevant anatomy
and probe placement. (B) Proximal MCL
(small red arrow). (C) POL (white arrow).

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A

179

B

Figure 6-29. SX view of the MCL and POL. (A) Relevant anatomy and probe placement. (B) Proximal MCL (red arrow)
and POL (white arrow).

A

B

Figure 6-30. Adductor magnus tendon. (A) Relevant anatomy and probe placement. (B) LX view of the adductor
magnus tendon (white arrows) attaching to the adductor tubercle, showing an oblique view of the MCL (red arrow).

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Chapter 6

A

B

Figure 6-31. Medial patellofemoral ligament. (A) Relevant anatomy and probe placement. (B) LX view of the medial
patellofemoral ligament (white arrows).

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181

Pes Anserine Tendons
1. Patient position: Same position as for MCL scanning
2. Probe/transducer position: The probe is placed in the LX view along the MCL, and the MCL
is followed distally just before its insertion at the tibia. Three diffused hypoechoic structures
can be visualized crossing over the MCL. By tilting the probe, the echotexture of the tendons
changes from hypoechoic to hyperechoic, which is due to anisotropy (Figure 6-32).

A

B

C
Figure 6-32. Pes anserine tendons.
(A) Relevant anatomy and probe
placement. (B) SX view of the pes
anserine tendons showing the sartorius
(white arrow), gracilis (small red arrow),
and semitendinosus (yellow arrow). (C)
LX view of the pes anserine tendon
(white arrows).

3. Relevant anatomy: From superior to inferior, the pes anserine tendons are arranged as sartorius, gracilis, and semitendinosus. The pes anserine bursa lies between the MCL and the pes
anserine tendons (see Figure 6-27).
4. Points to remember: Close to their distal insertion, the pes anserine tendons are thin, flattened
structures, and therefore the distinction between the tendons on ultrasound is based on their
relative position.

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LATERAL KNEE
Lateral Joint and Meniscus
1. Patient position: Knee flexed 30 degrees with a pillow between the knees for some varus stress
2. Probe/transducer position: The probe is placed along the lateral aspect of the knee joint in the
LX view (Figure 6-33).

A

B

Figure 6-33. Lateral meniscus. (A) Probe placement. (B) Lateral meniscus (white arrow) as a hyperechoic triangular
structure.

3. Relevant anatomy: The lateral meniscus appears as a hyperechoic triangular structure in the
lateral joint space.
4. Points to remember: You may need to increase gain, or brightness, to visualize the lateral
meniscus.

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Popliteus Tendon
1. Patient position: Same position as for the lateral joint
2. Probe/transducer position: The probe is placed along the lateral aspect of the knee joint in the
LX view, and attention is focused on the femur to visualize the groove where the popliteus
tendon sits. The popliteus tendon is visualized in the oblique SX in this view. The probe can
be rotated to be exactly short on the tendon and then rotated long on the tendon to obtain the
LX view (Figure 6-34).

A

B

C
Figure 6-34. Popliteus tendon. (A)
Probe placement. (B) SX view of the
popliteus tendon (white arrow) in the
popliteus groove of the femur. (C) LX
view of the popliteus tendon (white
arrow).

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3. Relevant anatomy: The popliteus muscle originates from the posteromedial aspect of the
proximal tibia above the soleal line. It is a thin, flat, triangular muscle that forms part of the
floor of the popliteal space. It continues superiorly and laterally, forming a tendon that lies
intracapsular laterally. The tendon attaches to the depression on the lateral aspect of the lateral
femoral condyle. The tendon passes beneath the LCL and biceps femoris tendon. The insertion
of the tendon is anteroinferior to the proximal attachment of the LCL. The popliteus bursa,
which lies between the posterior knee and the popliteus, is an extra-articular extension of the
synovial membrane of the knee joint. It extends from the popliteus hiatus to the proximal part
of the tendon. Other ligament attachments of popliteus include the popliteofibular ligament
and the ligament between the popliteus and the posterior horn of the lateral meniscus (Figure
6-35).4,5

Figure 6-35. Relevant anatomy of the popliteus muscle. (Ant. = anterior; PFL = popliteofibular ligament;
Post. = posterior.)

4. Points to remember: The popliteus tendon is intracapsular but extra-articular and extrasynovial. Repeated stress on the popliteus with activities like downhill walking or running can lead
to tendinosis or tenosynovitis.4

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Lateral Collateral Ligament
1. Patient position: Knee flexed 30 degrees with a pillow between the knees for some varus stress
2. Probe/transducer position: The probe is placed along the lateral aspect of the knee joint in the
LX view, visualizing the 3 bony landmarks; distal to proximal, they are the fibula, tibia, and
femur. The LCL is visualized from the distal attachment at the proximal end of the fibula to
the proximal attachment at the lateral condyle of the femur (Figure 6-36).

A

B

Figure 6-36. LCL. (A) Probe placement along the lateral aspect of the knee
joint in the LX view visualizing the 3 bony landmarks; distal to proximal, they
are the fibula, tibia, and femur. (B) LCL (white arrows). (F = fibula; P = popliteus
tendon.)

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3. Relevant anatomy: The LCL attaches on the lateral femoral condyle, anterior to the lateral head
of the gastrocnemius attachment and posterosuperior to the popliteus tendon attachment.
There is a conjoint attachment of the LCL and biceps femoris tendon on the proximal fibula
(Figures 6-37 and 6-38).6

Figure 6-37. Relevant anatomy of the lateral knee. (PFL = popliteofibular ligament.)

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187

Figure 6-38. Footprints of the LCL, popliteofibular ligament (PFL), and biceps femoris (BF) insertion on the proximal
fibula. (Ant. = anterior.)

4. Points to remember: Due to its course, the LCL may exhibit anisotropy close to its distal and
proximal portions.

Iliotibial Band
1. Patient position: Supine or side-lying
2. Probe/transducer position: The probe is placed on the lateral aspect of the knee with Gerdy’s tubercle as a bony landmark to orient the probe along the iliotibial band (Figures 6-39 through 6-41).

A

B

Figure 6-39. Iliotibial band. (A) Probe placement. (B) LX view of the iliotibial band (white arrows) attaching to Gerdy’s
tubercle.

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A

Chapter 6
B

Figure 6-40. Iliotibial band attachment to the patella. (A) Probe placement. (B) LX view of
the iliotibial band (white arrows) attachment to the patella.

Figure 6-41. Panoramic view of the iliotibial band (white arrows) attaching to Gerdy’s tubercle.

3. Relevant anatomy: The iliotibial band attaches to Gerdy’s tubercle on the anterolateral tibia
distally. Proximally, it is divided into superficial and deep layers, anchors the tensor fascia lata
muscle to the iliac crest, and receives most of the tendon of the gluteus maximus. The iliotibial band is dense, fibrous connective tissue that runs laterally from the iliac crest to Gerdy’s
tubercle on the lateral aspect of the thigh that passes over the femoral epicondyle, where it is
anchored by fibrous strands associated with a layer of fat that is richly innervated and vascularized.7 The iliotibial band has 2 distinct attachments to Gerdy’s tubercle of the tibia and to
the patella. The iliotibial band is an important dynamic stabilizer.
4. Points to remember: Gerdy’s tubercle is an important landmark in sonographic visualization
of the iliotibial band. From anterior to posterior, 3 important bony landmarks are seen: the
tibial tuberosity, Gerdy’s tubercle, and the head of the fibula.

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Biceps Femoris Tendon
1. Patient position: Prone or side-lying
2. Probe/transducer position: The probe is placed in the LX along the biceps femoris tendon distal
attachment at the fibular head, and the tendon is scanned proximally to scan the entire length
of the tendon. The SX view can be obtained by rotating the probe to place it transversely across
the tendon (Figure 6-42).

A

B

C

Figure 6-42. Biceps femoris tendon. (A) Probe placement. (B) LX view of the biceps femoris tendon (white arrow)
attaching to the fibula. (C) SX view of the biceps femoris tendon (white arrow) just proximal to the fibula.

3. Relevant anatomy: The biceps femoris muscle has 2 heads: (1) the long head that arises from
the medial aspect of the ischial tuberosity and (2) the short head that arises from the lateral
lip of the linea aspera, the proximal two-thirds of the supracondylar line of the femur, and
the lateral intermuscular septum. Distally, the tendon inserts on the head of fibula, the crural
fascia, and the proximal tibia.5,8
4. Points to remember: The biceps femoris long head is supplied by the tibial component of the
sciatic nerve, and the short head is supplied by the common peroneal component of the sciatic nerve. There may be selective atrophy of the short head of the biceps femoris in peroneal
neuropathy.

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Chapter 6

Common Fibular Nerve
1. Patient position: Prone or side-lying
2. Probe/transducer position: The probe is placed transversely across the common peroneal nerve
on the posterior aspect of the fibular head. After identifying the nerve, the LX view can be
obtained by rotating the probe (Figure 6-43).

A

B

C

Figure 6-43. Common fibular nerve.
(A) Probe placement. Patient is sidelying. (B) SX view of the nerve (white
arrow) showing the biceps femoris
tendon (small red arrow). (C) SX view
of the nerve (white arrow) around the
fibula neck.

3. Relevant anatomy: The common fibular nerve behind the fibular head is covered with skin
and subcutaneous tissue. As it courses around the fibular neck to move anteriorly, it is covered
by the peroneus longus muscle (fibular tunnel). The nerve then divides into superficial and
deep branches.9
4. Points to remember: The common fibular nerve appears as a hyperechoic flattened oval structure traveling between the fascial planes. The common fibular nerve view can be confirmed
by following it proximally at the level of the posterior knee where it joins the tibial counterpart
to form the sciatic nerve.

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191

POSTERIOR KNEE
Joint Anatomy
1. Patient position: Prone
2. Probe/transducer position:
a. SX view/transverse view: The probe is placed transversely across the popliteal aspect to
examine the joint and other soft tissue structures overlying the joint, such as tendons,
muscles, nerves, and blood vessels (Figure 6-44).

A

B

Figure 6-44. SX view of the posterior knee. (A) Probe placement. (B) SX view of the posterior knee showing the tibial
nerve (yellow arrow) and popliteal artery (red A).

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Chapter 6
b. LX view/longitudinal view: The probe is placed on the posterior aspect of the joint in the
LX. Sweeping the probe from medial to lateral examines the entire posterior aspect from
the medial femoral condyle to the lateral femoral condyle (Figures 6-45 and 6-46).

A

Figure 6-45. LX view of the
posterior knee. (A) Probe placement.
(B) Posterolateral LX view. (C)
Posteromedial LX view.

B

C

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A

193

B

Figure 6-46. LX view of the posterior
knee at the midline. (A) Probe
placement. (B) LX view of the posterior
knee at the midline showing the PCL
(white arrow) and joint capsule (red
arrow).

3. Relevant anatomy: At the midline, the capsule and a small portion of the PCL are visualized.
As you go lateral or medial, femoral condyles and articulating tibial bony interfaces are visualized, with some visualization of the menisci.
4. Points to remember: MRI is the best choice for cruciate ligament imaging, and ultrasound does
not give much information about ACL or PCL pathology. Indirect signs of an ACL tear can be
seen as a femoral notch sign, PCL wave sign, or capsular protrusion.10

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Chapter 6

Semimembranosus Muscle-Tendon Complex
1. Patient position: Prone
2. Probe/transducer position: The probe is placed transversely across the posteromedial aspect of
the knee at the level of the medial femoral condyle (Figure 6-47). For the LX view, the probe is
rotated 90 degrees from the SX view to visualize the tendon at its direct insertion site on the
tibia (Figure 6-48).

A

B

Figure 6-47. SX view of the
semimembranosus tendon. (A)
Probe placement. (B) SX view of
the semimembranosus tendon
(white arrow) also showing the
semitendinosus tendon (yellow arrow).

Figure 6-48. LX view of the semimembranosus tendon (white arrows) directly inserting on the tibia.

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195

3. Relevant anatomy: The distal semimembranosus muscle-tendon unit reinforces the posterior
aspect of the knee via multiple tendinous expansions. These distal expansions include the
oblique popliteal expansion, anterior expansion, and inferior expansion (direct tendon). The
oblique popliteal expansion is the most proximal limb that blends with the posterior capsule
to form the oblique popliteal ligament. The anterior expansion sends off fibers to the medial
meniscus and the MCL. The inferior expansion sends off fibers to the fascia of the popliteus
muscle and inserts at the posteroinferior aspect of the medial tibial condyle (direct tendon;
Figures 6-49 through 6-51).11

Figure 6-49. Relevant anatomy of the semimembranosus and its tendinous expansions.

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Chapter 6

A

B

Figure 6-50. Semimembranosus tendinous expansion to the popliteus muscle fascia. (A) Relevant anatomy and probe
placement. (B) Tendinous expansion (white arrows) to the popliteus muscle fascia.

A

B

Figure 6-51. Oblique popliteal ligament
expansion of the semimembranosus.
(A) Relevant anatomy and probe
placement. (B) Oblique popliteal
ligament (white arrows) blending with
the posterior capsule.

4. Points to remember: The semimembranosus is an important structure providing stability to
the posteromedial aspect of the knee. When present, the neck/stalk of Baker’s cyst can be seen
between the tendon of the semimembranosus and the medial gastrocnemius. Baker’s cyst is
essentially a bursal effusion of the semimembranosus and medial gastrocnemius tendon.

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197

Tibial Nerve and Blood Vessels
1. Patient position: Prone
2. Probe/transducer position: The probe is placed transversely at the posterior aspect of the knee
to scan the nerve in the SX view. The probe is moved in a proximal-to-distal direction to visualize the sciatic nerve splitting into the tibial and common peroneal counterparts. Once the
tibial nerve is confirmed, it can be scanned distally toward the leg (Figure 6-52).

A

Figure 6-52. Tibial nerve. (A) Probe
placement. (B) Tibial nerve (white
arrow), common fibular nerve (red
arrow), vein (V), and artery (white A).

B

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Chapter 6

3. Relevant anatomy: After splitting from the main trunk of the sciatic nerve, the tibial nerve
courses straight down from the popliteal fossa and passes deep to the gastrocnemius muscle.
4. Points to remember: The branching pattern may differ; therefore, it is recommended to scan
the nerve in the SX view in a proximal-to-distal direction to visualize the sciatic nerve splitting into the tibial and common fibular nerves (Figure 6-53).

Figure 6-53. Relevant anatomy of the sciatic nerve and its branches.

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199

REFERENCES
1.

Flores DV, Mejia Gomez C, Pathria MN. Layered approach to the anterior knee: normal anatomy and disorders
associated with anterior knee pain. Radiographics. 2018;38(7):2069-2101.
2. Liu F, Yue B, Gadikota HR, et al. Morphology of the medial collateral ligament of the knee. J Orthop Surg Res.
2010;5:69.
3. Saigo T, Tajima G, Kikuchi S, et al. Morphology of the insertions of the superficial medial collateral ligament
and posterior oblique ligament using 3-dimensional computed tomography: a cadaveric study. Arthroscopy.
2017;33(2):400-407.
4. Jadhav SP, More SR, Riascos RF, Lemos DF, Swischuk LE. Comprehensive review of the anatomy, function, and
imaging of the popliteus and associated pathologic conditions. Radiographics. 2014;34(2):496-513.
5. Rosas HG. Unraveling the posterolateral corner of the knee. Radiographics. 2016;36(6):1776-1791.
6. Chahla J, Moatshe G, Dean CS, LaPrade RF. Posterolateral corner of the knee: current concepts. Arch Bone Jt
Surg. 2016;4(2):97-103.
7. Fairclough J, Hayashi K, Toumi H, et al. The functional anatomy of the iliotibial band during flexion and extension of the knee: implications for understanding iliotibial band syndrome. J Anat. 2006;208(3):309-316.
8. Tubbs RS, Caycedo FJ, Oakes WJ, Salter EG. Descriptive anatomy of the insertion of the biceps femoris muscle.
Clin Anat. 2006;19(6):517-521.
9. Van den Bergh FR, Vanhoenacker FM, De Smet E, Huysse W, Verstraete KL. Peroneal nerve: normal anatomy
and pathologic findings on routine MRI of the knee. Insights Imaging. 2013;4(3):287-299.
10. Mautner K, Sussman WI, Nanos K, Blazuk J, Brigham C, Sarros E. Validity of indirect ultrasound findings in
acute anterior cruciate ligament ruptures. J Ultrasound Med. 2019;38(7):1685-1692.
11. Benninger B, Delamarter T. Distal semimembranosus muscle-tendon-unit review: morphology, accurate terminology, and clinical relevance. Folia Morphologica. 2013;72(1):1-9.

7
Hip
Mohini Rawat, DPT, MS, ECS, OCS, RMSK

Contents
• Anterior Hip
º Joint Anatomy
º Iliopsoas Tendon
º Tendons Originating From the Anterior Superior Iliac Spine
º Tendons Originating From the Anterior Inferior Iliac Spine
• Lateral Hip
º Greater Trochanter and Gluteal Tendon Attachments
• Posterior Hip
º Piriformis and Sciatic Nerve
º Other Small Rotators of the Hip
º Hamstring Tendon Origin at the Ischial Tuberosity
• Inguinal and Medial Hip Regions
º Inguinal Canal and Its Contents
º Adductor Group of Muscles

- 201 -

Rawat M.
Atlas of Musculoskeletal Ultrasound of the Extremities (pp 201-229).
© 2021 SLACK Incorporated.

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Chapter 7

ANTERIOR HIP
Joint Anatomy
1. Patient position: Supine with the hip in extension and slight abduction
2. Probe/transducer position: The probe is along the long axis (LX) of the femur anteriorly at the
level of greater trochanter (but not placed on the lateral aspect over the greater trochanter),
and then the probe is rotated medially toward the midline and moved proximally to be along
the LX of the femoroacetabular joint (Figures 7-1 through 7-3).
Figure 7-1. Probe positioning for the
LX view of the femoroacetabular joint.

A

B

Figure 7-2. LX view of the hip joint. (A) Probe placement. (B) LX view of the hip joint showing the acetabulum (Ace),
femoral head (FH), femoral neck (FN), iliopsoas muscle-tendon complex (IP), hyperechoic labrum (white arrow), and
hyperechoic capsuloligamentous layer (yellow arrow).

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A

203

B

Figure 7-3. Short axis (SX) view of the hip joint. (A) Probe placement. (B) SX view of the hip joint showing the femoral
head (FH), iliopsoas muscle-tendon complex (IP), hyperechoic femoral nerve (yellow arrow), and anechoic femoral
artery (red arrow).

3. Relevant anatomy: The acetabulum, labrum, and femoral head and neck are visualized.1 The
capsuloligamentous structure follows the bony contour of the head and neck of the femur.2
4. Points to remember: The joint is evaluated for excess fluid, capsular thickening, synovial
hypertrophy, labral pathology (limited view), loose bodies, or bony irregularity or erosion,
or to study the soft tissue structures overlying the joint like the iliopsoas bursa and iliopsoas
muscle-tendon complex. Femoroacetabular impingement is suspected with the following
changes in the anterior hip joint: presence of nonspherical head neck junction (cam deformity), focal bony protuberance at the femoral neck, or waist deficiency or convexity at the
femoral head-neck junction (Figure 7-4).3
Figure 7-4. The femoral head is
normally spherical. Femoroacetabular
impingement is suspected with the
following changes in the anterior hip
joint: presence of nonspherical headneck junction (cam deformity), focal
bony protuberance at the femoral
neck, or waist deficiency or convexity
at the femoral head-neck junction.

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Iliopsoas Tendon
1. Patient position: Supine using the flexion, abduction, and external rotation (FABER) maneuver, where the patient is asked to place the lateral aspect of the foot on the side to be studied
on the contralateral knee at the suprapatellar region4
2. Probe/transducer position: The probe is initially placed along the LX of the femoral head to
identify the iliopsoas tendon overlying the joint, then the iliopsoas tendon is followed to its
insertion site at the lesser trochanter (Figures 7-5 and 7-6).

A

Figure 7-5. LX view of the iliopsoas
tendon. (A) Probe placement with
the patient supine using the FABER
maneuver. The probe is initially placed
along the LX of the femoral head to
identify the iliopsoas tendon overlying
the joint, then the iliopsoas tendon
is followed to its insertion site at the
lesser trochanter. (B) LX view of the
hyperechoic iliopsoas tendon (white
arrows). (FH = femoral head; LT = lesser
trochanter.)

B

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A

205

B

Figure 7-6. (A) Relevant anatomy of the iliopsoas muscle-tendon complex. (B) Corresponding LX view of the iliopsoas
tendon (white arrows) inserting on the lesser trochanter (LT). (FH = femoral head.)

3. Relevant anatomy: The main tendon in the distal iliopsoas is the psoas tendon, including
fibers from the medial portion of the iliacus. The lateral iliacus muscle runs parallel to the
iliopsoas tendon and attaches directly onto the proximal femoral shaft (Figures 7-7 and 7-8).5,6

Figure 7-7. Relevant cross-sectional anatomy of the iliopsoas muscle-tendon complex at the level of the iliopectineal
eminence.

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Chapter 7
A

B

Figure 7-8. (A) SX view of the iliopsoas muscle-tendon complex at the level of
the iliopectineal eminence showing the lateral iliacus muscle (LI), medial iliacus
muscle (MI), tendon (T), psoas muscle (PM), and femoral artery (red A). (B) Relevant
anatomy

4. Points to remember: The most medial fibers of the iliacus form an accessory tendon that
merges with the psoas tendon to form the main tendon. There is a fatty fascial plane that
separates the distal iliopsoas tendon from the intramuscular tendon within the lateral portion
of the iliacus muscle, which should not be confused with a split tear of the iliopsoas muscletendon complex.5

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207

Tendons Originating From the Anterior Superior Iliac Spine
Anatomy of the anterior superior iliac spine (ASIS) and surrounding iliac crest region is shown
in Figures 7-9 and 7-10.

Figure 7-9. Relevant anatomy showing the footprints of various structures originating from the ASIS, iliac crest, and
ilium. (ITB = iliotibial band.)

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Chapter 7

Figure 7-10. Relevant anatomy of the iliotibial band and lateral thigh muscles. (ITB = iliotibial band; TFL = tensor fascia
lata.)

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209

1. Patient position: Supine
2. Probe/transducer position: The probe is placed in the SX orientation at the ASIS to evaluate the
sartorius and tensor fascia lata origin in SX view (Figure 7-11), and then rotated to LX orientation to evaluate the sartorius (Figure 7-12) followed by the tensor fascia lata, proximal iliotibial
band, and gluteal aponeurotic fascia in LX view (Figure 7-13). To scan these structures as they
attach to the pelvic bone, a good understanding of the anatomy is required.

A

B

C

Figure 7-11. SX view of the sartorius and tensor fascia lata. (A) Probe placement. First the probe is placed on the ASIS
and then moved slightly distal to visualize the sartorius medially and the tensor fascia lata laterally. (B) SX view at the
ASIS. (C) SX view at the level just distal to the ASIS showing the sartorius (S) medially and the tensor fascia lata (TFL)
laterally.

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Chapter 7

Figure 7-12. (A) SX view of the sartorius
(white arrow). (TFL = tensor fascia lata.)
(B) LX view of the sartorius (white arrow).

A

B

Figure 7-13. Panoramic view of the anterolateral thigh showing the tensor fascia lata (TFL), superficial layer of the
iliotibial band (yellow arrow), deep layer of iliotibial band (blue arrow), and common iliotibial band distally (white
arrow). (VL = vastus lateralis.)

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211

3. Relevant anatomy: The sartorius originates from the ASIS and runs anteromedially along the
thigh to attach to the proximal aspect of the medial tibial surface as the most proximal tendon
of the pes anserine tendons. The sartorius is a biarticular muscle, and the medial border of
the sartorius forms the lateral border of the femoral triangle. The iliotibial band has 3 layers:
superficial, intermediate, and deep. The superficial layer originates from the ilium superficial
to the origin of the tensor fascia lata muscle, the intermediate layer originates from the ilium
distal to the tensor fascia lata muscle, and the deep layer originates from the supra-acetabular
fossa between the hip joint capsule and the reflected head of the rectus femoris. Posteriorly,
the iliotibial band also receives tendinous fibers from the gluteal aponeurotic fascia and
gluteus maximus muscle. All the layers of iliotibial band merge together at the level of the
greater trochanter to continue distally along the entire length of the thigh and attach distally
at Gerdy’s tubercle of the tibia (see Figure 7-10).
4. Points to remember: The superficial layer of the iliotibial band is thicker posteriorly at the level
of the iliac tubercle compared with the anterior portion, which runs superficial to the tensor
fascia lata. The posterior contribution from the gluteal aponeurosis is much thinner. The tensor fascia lata muscle has a unique echotexture due to internal fat content.7,8

Tendons Originating From the Anterior Inferior Iliac Spine
1. Patient position: Supine
2. Probe/transducer position: The probe is placed in the LX orientation to the rectus femoris
direct head attachment at the anterior inferior iliac spine (AIIS; Figures 7-14 and 7-15). This
view can be obtained by first visualizing the femoral head-neck and then moving the probe
slightly proximal and lateral until the AIIS is visualized. To scan the indirect head of the
rectus femoris, the probe is moved slightly distal and lateral from the direct head with more
pressure on the proximal end of the probe to counter anisotropy because the indirect rectus
femoris fibers do not run parallel to the superficial structures (Figure 7-16).

A

B

Figure 7-14. LX view of the rector femoris. (A) Probe placement. (B) Hyperechoic rectus femoris direct head (white
arrow) attaching to the AIIS. The indirect head (yellow arrow) appears hypoechoic due to anisotropy as the tendon
attaches to the superolateral margin of the acetabulum.

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Chapter 7

Figure 7-15. Relevant anatomy of the rectus femoris tendon origin. The direct tendon of the rectus femoris arises from
the AIIS as a short, strong tendon. The indirect tendon of the rectus femoris arises from the superolateral margin of
the acetabulum.

A

Figure 7-16. Indirect head of the rectus
femoris. (A) Probe placement. (B) LX view
of the indirect head of the rectus femoris
(yellow arrow). The probe is moved slightly
distal and lateral from the direct head with
more pressure on the proximal end of the
probe to counter anisotropy.

B

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213

3. Relevant anatomy: The direct tendon of the rectus femoris arises from the AIIS as a short,
strong tendon. The indirect tendon of the rectus femoris arises from the superolateral margin
of the acetabulum (see Figure 7-15). The indirect tendon travels with the central aponeurosis
of the rectus femoris, and the direct tendon travels with the superficial fascia.1,2
4. Points to remember: In the LX view, the direct head appears as a hyperechoic fibrillar structure, whereas the indirect head appears as a hypoechoic structure due to anisotropy. Increase
the pressure on the proximal end of the probe in an attempt to counter anisotropy artifact to
visualize the indirect head better.

LATERAL HIP
Greater Trochanter and Gluteal Tendon Attachments
1. Patient position: Side-lying with the hip neutral to slight flexion
2. Probe/transducer position: The probe is placed on the lateral aspect of the thigh at the level of
the greater trochanter in the SX orientation. The SX orientation helps identify the bony facets
of the greater trochanter as anterior, lateral, superoposterior, and posterior (Figures 7-17 and
7-18). After identifying the bony facets of the greater trochanter, imaging can be focused on a
specific structure (eg, gluteus medius anterior or posterior band, gluteus minimus, or trochanteric bursa; Figures 7-19 through 7-22).2

Figure 7-17. The 4 facets of the greater trochanter: anterior, lateral, superoposterior, and posterior.

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Chapter 7

Figure 7-18. SX view of the greater
trochanter (GT) showing 3 facets:
anterior (A), lateral (L), and posterior
(P). The bony apex (white arrow) of
the greater trochanter differentiates
the anterior from the lateral facet.
The posterior facet is more rounded,
whereas the anterior and lateral
facets are flat.

Figure 7-19. Footprints of the gluteal tendons on the greater trochanter. The gluteus minimus attaches to the anterior
facet, the gluteus medius anterior band attaches to the lateral facet, and the gluteus medius posterior band attaches
to the superoposterior facet. (G = gluteus.)

Hip
A

215

B

Figure 7-20. LX view of the gluteus minimus. (A) Probe placement. The black star indicates the greater trochanter. (B)
LX view of the gluteus minimus (white arrow).

A

B

Figure 7-21. LX view of the gluteus medius anterior band. (A) Probe placement. The black star indicates the greater
trochanter. (B) LX view of the gluteus medius anterior band (white arrow).

216
A

Chapter 7
B

Figure 7-22. LX view of the gluteus medius posterior band. (A) Probe placement. The black star indicates the greater
trochanter. From the anterior band view, the probe is rotated slightly posterior, and pressure is increased on the
proximal end of the probe. (B) LX view of the gluteus medius posterior band (white arrow).

3. Relevant anatomy: The greater trochanter has 4 facets: anterior, lateral, superoposterior, and
posterior. The mean size of the facets is as follows: anterior = 2.6 × 3.0 cm; lateral = 2.0 × 3.7 cm;
superoposterior = 1.5 × 1.7 cm; posterior = 2.5 × 2.8 cm.9 The gluteus minimus attaches to the
anterior facet, the gluteus medius attaches to the lateral and superoposterior facets, and there
is no attachment on the posterior facet. The trochanteric bursa overlies the posterior facet. The
gluteus medius has 2 bands: anterior and posterior. The anterior band attaches to the lateral
facet, and the posterior band attaches to the superoposterior facet.9,10

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217

4. Points to remember:
a. It is important to remember that probe orientation will change slightly if the patient adds
more hip flexion or assumes a more comfortable fetal position for gluteal tendon scanning.
Adding more flexion will result in more anterior rotation of the tendon fibers.
b. The posterior band of the gluteus medius plays an important role in gait biomechanics; therefore, a tear of the posterior band is associated with greater discomfort and
impairment.11
c. There are bursae under the gluteus medius tendon (subgluteus medius bursa) and gluteus
minimus tendon (subgluteus minimus bursa) as they insert on the greater trochanter.9
d. The trochanteric bursa is also called the subgluteus maximus bursa (Figure 7-23). This
bursa is present between the gluteus medius tendon and the gluteus maximus muscle,
overlying the posterior facet of the greater trochanter, to prevent friction between the
greater trochanter and the gluteus maximus as it sends fibrous extensions to the fascia lata.
Branches of the inferior gluteal nerve supply the trochanteric bursa.12
Figure 7-23. The trochanteric bursa,
or subgluteus maximus bursa (white
arrows), is present between the
gluteus medius tendon (white star)
and gluteus maximus muscle (GMax),
overlying the posterior facet (P) of the
greater trochanter. (A = anterior facet;
L = lateral facet.)

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Chapter 7

POSTERIOR HIP
Piriformis and Sciatic Nerve
1. Patient position: Prone
2. Probe/transducer position: The probe is placed over the posterior aspect of the greater trochanter, transversely along the LX of the piriformis muscle. The probe is placed along the
imaginary line running between the sacrum and the greater trochanter. The sciatic nerve is
visualized in the SX, passing under the piriformis muscle to course distally toward the thigh
(Figure 7-24).

A

Figure 7-24. Piriformis muscle. (A)
Probe placement. (B) Piriformis muscle
(white arrow), sciatic nerve (yellow
arrow), and greater trochanter (GT).

B

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219

3. Relevant anatomy: The piriformis originates from the anterior surface of the sacrum at the
level of S2-S4 around the sacroiliac joint capsule and inserts as a short, round tendon on the
superomedial aspect of the greater trochanter (Figure 7-25). The sciatic nerve exits the greater
sciatic foramen, passing under the piriformis muscles. There are some variations in about
22% of the population where the sciatic nerve may pierce the piriformis, split the piriformis,
or both, in which one branch may pierce the piriformis muscle belly (usually the common
peroneal/fibular portion) and the other (the tibial portion) pass under or over the piriformis
muscle belly.13

Figure 7-25. Relevant anatomy of the piriformis, sciatic nerve, and other posterior hip musculature.

4. Points to remember: External rotation may help differentiate the piriformis from the overlying
gluteus maximus muscle. The piriformis attachment is very close to the gluteus medius attachment. Other internal rotators of the hip attach very close, slightly distal to the piriformis.

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Chapter 7

Other Small Rotators of the Hip
1. Patient position: Prone
2. Probe/transducer position: The probe is placed along the piriformis muscle as described in the
previous section. The probe is then moved slightly distal to evaluate the attachment of the
obturator externus and then the attachment of the quadratus femoris (Figures 7-26 and 7-27).

A

B

Figure 7-26. Obturator externus. (A) Relevant anatomy and probe placement. From the piriformis view, the probe is
moved slightly distal and rotated posteriorly to visualize the obturator externus tendon. (B) Obturator externus (white
arrows) and sciatic nerve (yellow arrow).

A

B

Figure 7-27. Quadratus femoris.
(A) Relevant anatomy and probe
placement. From the obturator
externus view, the probe is moved slightly distal, bridging the lateral aspect of the ischium and intertrochanteric
crest of the femur. (B) The quadratus femoris (white arrow) attaches medially on the lateral aspect of the ischium and
laterally on the intertrochanteric crest of the femur. It is a flat quadrilateral muscle. Also shown is the sciatic nerve
(yellow arrow).

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221

3. Relevant anatomy: The conjoint tendon is closely associated with the piriformis attachment,
with fibroconnective interdigitations present. The superior gemellus, obturator internus, and
inferior gemellus form a single tendon at the level of the head-neck junction and pass obliquely
inferior and anterior to the piriformis to insert near the anterior tip of the greater trochanter.
The obturator externus courses anterior and superior to the quadratus femoris to insert on the
obturator fossa, which is present at the junction of the femoral neck and the medial face of the
greater trochanter. The quadratus femoris has a teardrop-shaped footprint on the posterior
femur, overlying the inferior margin of the intertrochanteric crest. The quadratus femoris
is a rectangular-shaped muscle that covers the posterior aspect of the obturator externus
(Figure 7-28).14

Figure 7-28. Relevant anatomy of the footprints of the posterior hip muscles.

4. Points to remember: The small rotators of the hip are challenging structures to visualize with
ultrasound because they are deeper and smaller structures. Knowledge of their anatomy and
their relative position is vital to visualize the structures. In ischiofemoral impingement, the
quadratus femoris muscle may present with edema.

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Chapter 7

Hamstring Tendon Origin at the Ischial Tuberosity
1. Patient position: Prone
2. Probe/transducer position: The probe is placed in the SX at the ischial tuberosity to scan the
hamstring tendons in the SX (Figure 7-29). The probe can be moved distally in the SX view
to visualize the hamstring muscle-tendon complex in the SX. The probe is then moved in the
LX orientation to visualize tendons in the LX in a proximal-to-distal direction (Figure 7-30).

A

B

Figure 7-29. Hamstring tendon origin.
(A) Probe placement. (B) SX view of
the hamstring tendon origin from the
ischial tuberosity (Isch T) showing the
conjoint tendon of the biceps femoris
and semitendinosus (white arrow),
semimembranosus tendon (blue
arrow), and sciatic nerve (yellow arrow).

A

Figure 7-30. LX view of the hamstring
tendon. (A) Probe placement. (B) LX
view of the hamstring tendon (white
arrow) origin at the ischial tuberosity
(Isch T).

B

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3. Relevant anatomy: There is a conjoint insertion of the biceps femoris and semitendinosus at
the ischial tuberosity that is medial and superficial. The semimembranosus tendon is lateral
and deep and immediately medial to the sciatic nerve (Figures 7-31 and 7-32).2 There are 2
bursae in this region: the bursa of the ischial tuberosity that overlies the bony prominence and
the bursa of the proximal biceps femoris that can be present between the common attachment
of the biceps femoris (semitendinosus and semimembranosus attachment). The sciatic nerve
can be seen overlying the quadratus femoris muscle. Parallel to the sciatic nerve is the posterior femoral cutaneous nerve and its perineal branches. The perineal branches of the posterior
femoral cutaneous nerve supply the bursa of the ischial tuberosity.15

Figure 7-31. Relevant anatomy of the hamstring tendon attachment at the ischial tuberosity. The conjoint insertion
of the biceps femoris and semitendinosus at the ischial tuberosity is medial and superficial. The semimembranosus
tendon is lateral and deep.

224
A

Chapter 7
B

Figure 7-32. Relevant anatomy of the individual muscle-tendon units of the hamstring group. (A) Biceps femoris (long
and short heads) and semitendinosus. (B) Semimembranosus.

4. Points to remember: The biceps femoris short head originates from the middle third of the
femur from the lateral lip of the linea aspera and descends laterally for the common attachment of the long and short head at the fibular head.15
Injury of the conjoint tendon of the biceps femoris and semitendinosus is the most common sports injury, and it is important to determine whether it is a free-tendon or myotendinous injury.16
Ultrasound imaging and magnetic resonance imaging (MRI) are the imaging modalities of
choice for hamstring muscle complex pathology. Combined with a good understanding of the
anatomy, imaging of the hamstring muscle complex will help differentiate a wide spectrum of
injuries and pathology at this area.17

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225

INGUINAL AND MEDIAL HIP REGIONS
Inguinal Canal and Its Contents
Anatomy of the lateral femoral cutaneous nerve (LFCN), femoral nerve, vessels, and other soft
tissue structures is shown in Figure 7-33.

Figure 7-33. Relevant anatomy of the inguinal canal.

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Chapter 7

1. Patient position: Supine
2. Probe/transducer position: The probe is placed along the inguinal ligament, with the ASIS as a
bony landmark. Structures passing under the inguinal ligaments are visualized (Figure 7-34).

Figure 7-34. Inguinal ligament (white arrows), femoral nerve (yellow arrow), femoral artery (red A), and femoral vein
(V).

3. Relevant anatomy: From lateral to medial, structures are arranged as follows: LFCN, iliacus
and psoas muscle and tendon complex, femoral nerve, femoral artery, femoral vein, femoral
ring, pectineus muscle.
4. Points to remember: The LFCN appears as a small, round, flattened, hypoechoic structure
between 2 fascial layers: the fascia lata and fascia iliaca (Figure 7-35). It is a pure sensory nerve
and may show anterior and posterior division over the sartorius muscle. Anatomical variations are common. It is difficult to evaluate on MRI; therefore, ultrasound is the preferred
choice for LFCN imaging.18
Figure 7-35. A shallow depth and
higher frequency probe are needed
to visualize the LFCN (yellow arrow).

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227

Adductor Group of Muscles
1. Patient position: Supine with the hip in external rotation or frog-leg position
2. Probe/transducer position: The probe is placed in the LX over the pubic symphysis to visualize
the common adductor tendon attachment (Figures 7-36 and 7-37).

A

B

Figure 7-36. LX view of the adductor tendon origin at the pubis. (A) Probe
placement. (B) LX view of the common adductor tendon (white arrow) origin at the
pubis. Distally, each muscle can be seen from superficial to deep: adductor longus
(Add L), adductor brevis (Add B), and adductor magnus (Add M).

Figure 7-37. The relevant anatomy of the adductor tendons.

228

Chapter 7

3. Relevant anatomy: The adductor longus has a tendinous attachment on the anterior pubic
body. It is contiguous with the rectus abdominis aponeurosis (Figure 7-38). Posterior to the
tendon, the adductor longus has a direct muscle attachment to the pubis. The adductor brevis
originates immediately posterior and lateral to the adductor longus and is also contiguous
with the rectus abdominis aponeurosis. The adductor magnus originates from the lower border of the inferior pubic ramus, ischial ramus, and ischial tuberosity. The gracilis originates
from the anterior aspect of the pubic body and inferior pubic ramus.2

Figure 7-38. Relevant anatomy of the adductor group of muscles and the rectus abdominis aponeurosis.

4. Points to remember: The rectus abdominis aponeurosis and adductor longus can be seen
blending at the pubic symphysis. It is difficult to differentiate each of the adductor tendons
proximally. Distally, the adductor longus is the most superficial, and the adductor brevis and
adductor magnus are deep to it.2

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229

REFERENCES
1.
2.
3.

4.
5.
6.
7.
8.
9.

10.
11.
12.
13.
14.
15.
16.
17.
18.

Molini L, Precerutti M, Gervasio A, Draghi F, Bianchi S. Hip: anatomy and US technique. J Ultrasound.
2011;14(2):99-108.
Lungu E, Michaud J, Bureau NJ. US assessment of sports-related hip injuries. Radiographics. 2018;38(3):867-889.
Buck FM, Hodler J, Zanetti M, Dora C, Pfirrmann CW. Ultrasound for the evaluation of femoroacetabular
impingement of the cam type: diagnostic performance of qualitative criteria and alpha angle measurements.
Eur Radiol. 2011;21(1):167-175.
Balius R, Pedret C, Blasi M, et al. Sonographic evaluation of the distal iliopsoas tendon using a new approach.
J Ultrasound Med. 2014;33(11):2021-2030.
Polster JM, Elgabaly M, Lee H, Klika A, Drake R, Barsoum W. MRI and gross anatomy of the iliopsoas tendon
complex. Skeletal Radiol. 2008;37(1):55-58.
Guillin R, Cardinal E, Bureau NJ. Sonographic anatomy and dynamic study of the normal iliopsoas musculotendinous junction. Eur Radiol. 2009;19(4):995-1001.
Deshmukh S, Abboud SF, Grant T, Omar IM. High-resolution ultrasound of the fascia lata iliac crest attachment:
anatomy, pathology, and image-guided treatment. Skeletal Radiol. 2019;48(9):1315-1321.
Hyland S, Varacallo M. Anatomy, bony pelvis and lower limb, iliotibial band (tract). In: StatPearls. Treasure
Island, FL: StatPearls Publishing; 2019. Updated January 4, 2019.
Pfirrmann CW, Chung CB, Theumann NH, Trudell DJ, Resnick D. Greater trochanter of the hip: attachment
of the abductor mechanism and a complex of three bursae—MR imaging and MR bursography in cadavers and
MR imaging in asymptomatic volunteers. Radiology. 2001;221(2):469-477.
Robertson WJ, Gardner MJ, Barker JU, Boraiah S, Lorich DG, Kelly BT. Anatomy and dimensions of the gluteus
medius tendon insertion. Arthroscopy. 2008;24(2):130-136.
Hoffman DF, Smith J. Sonoanatomy and pathology of the posterior band of the gluteus medius tendon.
J Ultrasound Med. 2017;36(2):389-399.
Dunn T, Heller CA, McCarthy SW, Dos Remedios C. Anatomical study of the “trochanteric bursa.” Clin Anat.
2003;16(3):233-240.
Boyajian-O’Neill LA, McClain RL, Coleman MK, Thomas PP. Diagnosis and management of piriformis syndrome: an osteopathic approach. J Am Osteopath Assoc. 2008;108(11):657-664.
Philippon MJ, Michalski MP, Campbell KJ, et al. Surgically relevant bony and soft tissue anatomy of the proximal femur. Orthop J Sports Med. 2014;2(6):2325967114535188.
Stępień K, Śmigielski R, Mouton C, Ciszek B, Engelhardt M, Seil R. Anatomy of proximal attachment, course, and
innervation of hamstring muscles: a pictorial essay. Knee Surg Sports Traumatol Arthrosc. 2019;27(3):673-684.
Balius R, Pedret C, Iriarte I, Sáiz R, Cerezal L. Sonographic landmarks in hamstring muscles. Skeletal Radiol.
2019;48(11):1675-1683.
Koulouris G, Connell D. Hamstring muscle complex: an imaging review. Radiographics. 2005;25(3):571-586.
Tagliafico A, Bignotti B, Rossi F, Sconfienza LM, Messina C, Martinoli C. Ultrasound of the hip joint, soft tissues, and nerves. Semin Musculoskelet Radiol. 2017;21(5):582-588.

8
Peripheral Nerves
Mohini Rawat, DPT, MS, ECS, OCS, RMSK

Contents
• Upper Extremity Nerves
º Brachial Plexus and Thoracic Outlet
▪ Cervical Nerve Roots
▪ Vagus Nerve and Cervical Ganglion
▪ Greater Auricular Nerve
▪ Spinal Accessory Nerve
▪ Dorsal Scapular Nerve
▪ Facial Nerve
▪ Greater and Lesser Occipital Nerves
▪ Phrenic Nerve
▪ Subclavian Nerve
▪ Long Thoracic Nerve
º Shoulder and Arm Region
▪ Suprascapular Nerve
▪ Axillary Nerve
▪ Ulnar, Median, Radial, and Musculocutaneous Nerves

- 231 -

Rawat M.
Atlas of Musculoskeletal Ultrasound of the Extremities (pp 231-287).
© 2021 SLACK Incorporated.

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Chapter 8

º Elbow and Forearm Region
▪ Lateral Antebrachial Cutaneous Nerve
▪ Medial Antebrachial Cutaneous Nerve
▪ Posterior Antebrachial Cutaneous Nerve
▪ Ulnar Nerve
▪ Radial Nerve and Its Branches
▪ Median and Anterior Interosseous Nerves
º Wrist, Hand, and Digits
▪ Median Nerve
▪ Palmar Cutaneous Branch of the Median Nerve
▪ Ulnar Nerve
▪ Dorsal Ulnar Cutaneous Nerve
▪ Digital Nerves
• Lower Extremity Nerves
º Hip and Pelvic Region
▪ Lateral Femoral Cutaneous Nerve
▪ Ilioinguinal and Iliohypogastric Nerves
▪ Pudendal Nerve
▪ Femoral and Saphenous Nerves
▪ Obturator Nerve
▪ Sciatic Nerve
º Knee and Lower Leg Region
▪ Tibial and Common Fibular Nerves and Their Branches
▪ Sural Nerve
▪ Saphenous Nerve
º Ankle and Foot Region
▪ Deep Peroneal Nerve
▪ Superficial Peroneal Sensory Nerve
▪ Tibial Nerve at the Tarsal Tunnel and Its Branches
▪ Medial Plantar Nerve
▪ Lateral Plantar Nerve
▪ Digital Nerves

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233

UPPER EXTREMITY NERVES
Brachial Plexus and Thoracic Outlet
Cervical Nerve Roots
1. Probe/patient position: The patient’s head is rotated to the opposite side, and the probe is positioned on the sagittal oblique axis over the scalene anterior, perpendicular to the supraclavicular vessels, to visualize the cervical nerve roots in the short axis (SX) from C5-C8. Tracing the
nerve roots proximally, C5 and C6 can be seen emerging between the anterior and posterior
tubercles (Figure 8-1). The C7 nerve root lacks an anterior tubercle (Figure 8-2). Moving a
few millimeters distally, the trunk level can be visualized in the long axis (LX) through the
acoustic window of the scalene middle (Figures 8-3 through 8-5). Further distally, at the level
of lateral third of the supraclavicular fossa and between the clavicle and first rib in the sagittal oblique view, 6 divisions of the brachial plexus appear as a cluster of hypoechoic fascicles
between the omohyoid muscle and the subclavian artery and vein (Figure 8-6). The cord level
of the brachial plexus is best visualized in the subpectoralis minor space, where the probe is
placed in the sagittal oblique orientation over the pectoralis minor muscle and the axillary
artery is identified (Figure 8-7). The posterior, medial, and lateral cords are identified around
the axillary artery as hyperechoic structures.1-4

A

Figure 8-1. C5 nerve root. (A) Probe
placement. (B) SX view of the C5 nerve
root (yellow arrow) emerging between
the anterior tubercle (AT) and posterior
tubercle (PT).

B

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Chapter 8

Figure 8-2. C7 nerve root (yellow arrow), posterior tubercle (PT), and overlying C5 and C6
nerve roots (white arrows).

Figure 8-3. SX view of the C5 (white arrow), C6 (yellow arrow), C7 (blue arrow), C8 (red arrow),
and T1 (green arrow) nerve roots emerging between the anterior scalene (AS) and middle
scalene (MS) muscles. Also shown is the overlying sternocleidomastoid muscle (SCM).

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A

235

B

Figure 8-4. LX view of the C5, C6, and
C7 nerve roots. (A) Probe placement.
(B) LX view of the nerve roots as they
emerge between the anterior and
posterior tubercles (T).

Figure 8-5. LX view, slightly distal
to the view in Figure 8-4, showing
C5, C6, C7, and C8 nerve roots.

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Chapter 8

A

B

Figure 8-6. Six divisions of the brachial
plexus. (A) Probe placement. (B) SX view
at the division level (white arrows). The
brachial plexus appears as a cluster of
hypoechoic fascicles between the
omohyoid muscle (red arrow), the
subclavian artery (red A), and vein (blue V).

A

Figure 8-7. Cord level of the brachial
plexus in the subpectoralis minor
space. (A) Probe placement in the
sagittal oblique orientation over the
pectoralis minor muscle and axillary
artery. (B) Posterior (blue arrow), medial
(yellow arrow), and lateral (white arrow)
cords are identified around the axillary
artery (red A) as hyperechoic structures.
(PMin = pectoralis minor muscle.)

B

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237

2. Landmarks:
a. External: Posterior border of the sternocleidomastoid muscle or scalene anterior muscle
b. Internal: Anterior scalene muscle, middle scalene muscle, anterior and posterior tubercles
of the vertebra, subclavian artery, carotid artery
3. Relevant anatomy: The brachial plexus arises from the ventral rami of the C5-T1. C8 and T1
are difficult to visualize with ultrasound.
4. Points to remember: Rami or roots are identified by the tubercles on the transverse process.
The C5 and C6 roots are between the anterior and posterior tubercles. The C7 nerve root
lacks an anterior tubercle, and only the posterior tubercle is seen. The brachial plexus is best
imaged in the SX view for better identification, and then LX views can be obtained at the area
of interest.

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Chapter 8

Vagus Nerve and Cervical Ganglion
1. Probe/patient position: The probe is placed transversely over the sternocleidomastoid muscle at
the level of the C6 anterior tubercle. The vagus nerve is visualized between the carotid artery
and internal jugular vein (Figure 8-8).4

A

B

Figure 8-8. Vagus nerve. (A) Probe
placement transversely over the
sternocleidomastoid muscle at the
level of the C6 anterior tubercle. (B)
With the sternocleidomastoid muscle
(SCM) as the most superficial structure
and the thyroid gland (Thy) medially,
the vagus nerve (yellow arrow) is
visualized between the internal carotid artery (CA) and internal jugular vein (JV), inside the carotid sheath.

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239

2. Landmarks: With the sternocleidomastoid as the most superficial structure and the thyroid
gland medially, the vagus nerve is visualized between the internal carotid artery and internal
jugular vein, inside the carotid sheath. Lateral to the carotid artery are the longus capitis and
longus colli muscles. The cervical ganglion can be seen between the longus capitis and longus
colli muscles (Figure 8-9).4
Figure 8-9. Cervical ganglion.
Probe placement is the same as
for the vagus nerve, with slightly
lateral placement. Lateral to
the carotid artery (CA) are the
longus capitis (LCA) and longus
colli (LCO) muscles. The cervical
ganglion (white arrow) can be
seen between them. (JV = jugular
vein; SCM = sternocleidomastoid
muscle; Thy = thyroid gland.)

3. Relevant anatomy: The vagus nerve is the tenth cranial nerve with both motor and sensory
fibers.5
4. Points to remember: There are 3 cervical ganglia connected by intervening cords: superior,
middle, and inferior. At the level of the C6 vertebra, the middle cervical ganglion can be seen;
it receives ganglia contribution from C5 and C6.5

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Chapter 8

Greater Auricular Nerve
1. Probe/patient position: The patient’s head is rotated to the opposite side, and the probe is
placed posteriorly on the sternocleidomastoid muscle in the slight sagittal oblique axis in the
upper third of the muscle. The greater auricular nerve is visualized overlying the sternocleidomastoid muscle (Figure 8-10).4

A

B

Figure 8-10. Greater auricular nerve.
(A) Probe placement posteriorly on
the sternocleidomastoid muscle in the
slight sagittal oblique axis in the upper third of the muscle. (B) The greater auricular nerve (white arrow) is visualized
overlying the sternocleidomastoid muscle (SCM).

2. Landmark: Sternocleidomastoid muscle in the upper third of the muscle belly
3. Relevant anatomy: The greater auricular nerve originates from the cervical plexus and is
composed of the C2 and C3 spinal nerves. It emerges around the posterior border of the sternocleidomastoid muscle and ascends superiorly to give sensory innervation to the skin over
the parotid gland, mastoid process, and outer ear.5

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241

Spinal Accessory Nerve
1. Probe/patient position: The patient’s head is rotated to the opposite side, and the probe is
placed on the sternocleidomastoid muscle in the sagittal oblique axis in the upper third of the
muscle in a posterior-to-anterior orientation. The spinal accessory nerve is visualized within
the belly of the sternocleidomastoid muscle (Figure 8-11).4

A

B

Figure 8-11. Spinal
accessory
nerve. (A) Probe placement on the
sternocleidomastoid muscle in the
sagittal oblique axis in the upper third
of the muscle in a posterior-to-anterior
orientation. (B) The spinal accessory
nerve (white arrow) is visualized within
the belly of the sternocleidomastoid
muscle.

2. Landmark: Sternocleidomastoid muscle in the upper third of the belly
3. Relevant anatomy: The spinal accessory nerve is the 11th cranial nerve. It gives motor innervation to the sternocleidomastoid and trapezius muscles. It pierces the sternocleidomastoid
muscle and courses obliquely across the posterior triangle of the neck. As it traverses the
sternocleidomastoid muscle, it gives innervating branches to the muscle and is then joined by
branches from the C2, C3, and C4 spinal nerve roots posteriorly to form a plexus that gives
innervation to the trapezius muscle.5

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Chapter 8

Dorsal Scapular Nerve
1. Probe/patient position: The patient’s head is rotated to the opposite side, and t he probe is
placed in the sagittal oblique axis, posterior to the sternocleidomastoid muscle and over the
middle scalene belly at the level of the C5 nerve root. The dorsal scapular nerve is visualized
within the middle scalene muscle belly (Figure 8-12).4

A

B

Figure 8-12. Dorsal scapular nerve.
(A) Probe placement in the sagittal
oblique axis, posterior to the
sternocleidomastoid muscle and over
the middle scalene belly at the level of
the C5 nerve root. (B) The dorsal scapular nerve (white arrow) is visualized within the middle scalene (MS) muscle belly.

2. Landmarks: Middle scalene muscle and C5 nerve root
3. Relevant anatomy: The dorsal scapular nerve arises from the brachial plexus and has fiber
contribution from the C5 nerve root. It gives motor innervation to the rhomboids and levator
scapulae muscle. It pierces the middle scalene and then passes beneath the levator scapulae
muscle as it courses posteriorly.3,5

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243

Facial Nerve
1. Probe/patient position: The patient’s head is rotated to the opposite side, and the probe is
placed along the LX of the nerve just below the ear. The nerve is visualized in the LX going
through the parotid gland (Figure 8-13).6

A

B

Figure 8-13. Facial nerve. (A) Probe
placement. (B) The facial nerve (white
arrows) is visualized in the LX going
through the parotid gland (PG).

2. Landmarks:
a. Internal: Parotid gland
b. External: Just below the ear
3. Relevant anatomy: The facial nerve is the seventh cranial nerve. It exits the skull through the
stylomastoid foramen and divides into 5 branches as it pierces through the parotid gland:
temporal, zygomatic, buccal, mandibular, and cervical.

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Chapter 8

Greater and Lesser Occipital Nerves
1. Probe/patient position:
a. Greater occipital nerve: The probe is placed in an oblique axis between the spinous process
of the C2 and mastoid process. The greater occipital nerve is visualized between the semispinalis capitis and obliquus capitis inferior muscles (Figure 8-14).4

A

Figure 8-14. Greater occipital nerve.
(A) Probe placement in the oblique
axis between the spinous process of
the C2 and mastoid process. (B) The
greater occipital nerve (white arrow)
is visualized between the semispinalis
capitis (SSC) and obliquus capitis
inferior (OCI) muscles.

B

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245

b. Lesser occipital nerve: The patient’s head is rotated to the opposite side, and the probe is
placed transversely on the posterior border of the sternocleidomastoid at the level of the
upper third of the muscle, just below the hairline. The lesser occipital nerve is visualized
between the sternocleidomastoid and levator scapulae muscles (Figure 8-15).

A

B

Figure 8-15. Lesser occipital nerve.
(A) Probe placement transversely
on the posterior border of the
sternocleidomastoid muscle at the
level of the upper third of the muscle,
just below the hairline. (B) The lesser
occipital nerve (white arrow) is visualized between the sternocleidomastoid (SCM) and levator scapulae (LS) muscles.

2. Landmarks:
a. Greater occipital nerve: The spinous process of the C2 and mastoid process are external
landmarks. The semispinalis capitis and obliquus capitis inferior muscles are internal
landmarks.
b. Lesser occipital nerve: The posterior border of the sternocleidomastoid and levator scapulae muscles. The levator scapulae muscle is lined by the hyperechoic deep cervical fascia.
3. Relevant anatomy: The greater occipital nerve arises from the medial branch of the dorsal
ramus of the C2. The lesser occipital nerve arises from the ventral ramus of the C2.

246

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Phrenic Nerve
1. Probe/patient position: The patient’s head is rotated to the opposite side, and the probe is
placed on the sternocleidomastoid muscle at the level of the mid-belly. The phrenic nerve is
visualized superficial to the anterior scalene muscle and deep to the thyrocervical trunk of the
subclavian artery (Figure 8-16).4

A

B

Figure 8-16. Phrenic nerve. (A) Probe
placement on the sternocleidomastoid
muscle at the mid-belly level. (B)
The phrenic nerve (yellow arrow) is
visualized superficial to the anterior
scalene muscle (AS).

2. Landmarks:
a. External: Posterior border of the sternocleidomastoid muscle at the mid-belly level
b. Internal: Anterior scalene muscle and thyrocervical trunk of the subclavian artery and
sternocleidomastoid muscle
3. Relevant anatomy: The phrenic nerve originates from the anterior division of C3, C4, and C5.
It receives contribution from both the cervical plexus and brachial plexus.

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247

Subclavian Nerve
1. Probe/patient position: The patient’s head is rotated to the opposite side, and the probe is
placed above and along the clavicle. The subclavian nerve is visualized just above the subclavian artery. Immediately next to it, the brachial plexus cluster can be visualized (Figure 8-17).4

A

B

Figure 8-17. Subclavian nerve. (A)
Probe placement above and along
the clavicle. (B) The subclavian nerve
(between the yellow arrows) is
visualized just above the subclavian
artery (A) and immediately next to the
brachial plexus cluster (white arrows).

2. Landmarks:
a. External: Clavicle
b. Internal: Subclavian artery and brachial plexus
3. Relevant anatomy: The subclavian nerve originates from the junction point of the C5 and C6
nerve roots. It is connected by a filament with the phrenic nerve.5

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Chapter 8

Long Thoracic Nerve
1. Probe/patient position: The probe is placed in the SX over the middle scalene muscle at the
level of the C5 and C6 nerve root. The long thoracic nerve is visualized within the middle
scalene muscle, posterior to the C5 and C6 nerve roots (Figure 8-18).4

A

B

Figure 8-18. Long thoracic nerve.
(A) Probe placement in the SX over
the middle scalene muscle at the level
of the C5 and C6 nerve roots. (B) The
long thoracic nerve (yellow arrow) is
visualized within the middle scalene
muscle, posterior to the C5 and C6
nerve roots.

2. Landmarks: Middle scalene muscle and C5 and C6 nerve roots
3. Relevant anatomy: The long thoracic nerve arises from the C5, C6, and C7 nerve roots and
supplies the serratus anterior muscle.5

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249

Shoulder and Arm Region
Suprascapular Nerve
1. Probe/patient position:
a. Suprascapular notch: The probe is positioned over the suprascapular notch and aligned
along the direction of the axis of the coracoid process. The suprascapular nerve is visualized in the suprascapular notch with the superior transverse ligament overlying it and the
suprascapular artery superficial to the ligament (Figure 8-19).

A

B

Figure 8-19. Suprascapular nerve from
the suprascapular notch. (A) Probe
placement over the suprascapular
notch, with the probe aligned along
the direction of the axis of the coracoid process. (B) Suprascapular nerve (yellow arrow) and artery (red arrow).

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Chapter 8

b. Spinoglenoid notch: The probe is placed over the posterior glenohumeral joint and then
moved medially and rotated slightly in the SX to the spinoglenoid notch area. The suprascapular nerve is visualized with the suprascapular artery in the notch (Figure 8-20).7

A

B

Figure 8-20. Suprascapular nerve
from the spinoglenoid notch. (A)
Probe placement over the posterior
glenohumeral joint, then moved
medial and rotated slightly to the SX
view of the spinoglenoid notch area. (B)
Suprascapular nerve (yellow arrow) and
artery (red area).

2. Landmarks: Suprascapular notch and coracoid process (for probe orientation); spinoglenoid
notch and posterior glenohumeral joint
3. Relevant anatomy: The supraspcapular nerve arises from the superior trunk of the brachial
plexus and has fibers derived from the C5 and C6 nerve roots. It gives motor supply to the
supraspinatus and infraspinatus muscles and sensory innervation to the acromioclavicular
joint, subacromial bursa, and glenohumeral joint.
4. Points to remember: It is important to turn on color Doppler mode to identify the artery, which
helps in visualization of suprascapular nerve. The artery is superficial to the superior transverse ligament in the suprascapular notch. The artery accompanies the suprascapular nerve
in the spinoglenoid notch.

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251

Axillary Nerve
1. Probe/patient position: The posterior cord from the subpectoralis minor space is followed
laterally to visualize the axillary nerve between the subscapularis and coracobrachialis/short
head of the biceps muscle (Figure 8-21). The probe is placed in the LX on the posterior aspect
of the shoulder at the level of the teres minor muscle. The axillary nerve (posterior branch) is
seen between the teres minor and the lateral head of the triceps, overlying the humeral bony
interface and accompanied by the posterior circumflex humeral artery (Figure 8-22).1
A

B

Figure 8-21. Axillary nerve anteriorly.
(A) Probe placement. The posterior
cord of the subpectoralis minor space
is followed laterally to visualize the axillary nerve between the subscapularis and coracobrachialis/short head of the
biceps muscle. (B) The axillary nerve (yellow arrow) is seen between the subscapularis (SubS) and coracobrachialis/
short head of the biceps muscle (small white B).

A

B

Figure 8-22. Axillary nerve posteriorly.
(A) Probe placement in the LX on the
posterior aspect of the shoulder at the
level of the teres minor muscle. (B) The
axillary nerve posterior branch (yellow
arrow) is seen between the teres minor
(TM) and lateral head of the triceps,
overlying the humeral bony interface and accompanied by the posterior circumflex humeral artery (red arrow).

2. Landmarks: The teres minor muscle, lateral head of the triceps, and posterior circumflex
artery are internal landmarks.
3. Relevant anatomy: The axillary nerve arises from the posterior cord of the brachial plexus and
derives fibers from the C5 and C6 roots.

252

Chapter 8

Ulnar, Median, Radial, and Musculocutaneous Nerves
1. Probe/patient position: The probe is placed in the oblique LX along the anterior axillary fold, and
the axillary artery is identified. With respect to the axillary artery, the median nerve is lateral,
the ulnar nerve is medial, and the radial nerve is posterior (Figure 8-23). Laterally, the musculocutaneous nerve is seen between the biceps brachii and coracobrachialis muscles (Figure 8-24).3
A

B

Figure 8-23. Median, ulnar, and radial
nerves at the anterior axillary fold. (A)
Probe placement. (B) Median (yellow
arrow), ulnar (white arrow), and radial
(red arrow) nerves around the axillary
artery (white A).
Figure 8-24. The musculocutaneous
nerve (white arrow) is seen between
the biceps brachii (SHbr) and
coracobrachialis (Cbr) muscles.

2. Landmarks:
a. External: Anterior axillary fold
b. Internal: Axillary artery as an internal landmark for the median, ulnar, and radial nerves;
biceps brachii and coracobrachialis muscles as internal landmarks for the musculocutaneous
nerve

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253

Elbow and Forearm Region
Lateral Antebrachial Cutaneous Nerve
1. Probe/patient position: The probe is placed transversely at the elbow crease to visualize the
lateral antebrachial cutaneous (LABC) nerve in the SX view. The LABC nerve is visualized
lateral to the distal biceps tendon, just below or next to the cephalic vein (Figure 8-25). Tracing
the nerve proximally, it can be seen joining the musculocutaneous nerve.8

A

B

Figure 8-25. LABC nerve. (A) Probe placement transversely at the elbow
crease. (B) The LABC nerve (white arrow) is visualized lateral to the distal
biceps tendon (BT), just below or next to the cephalic vein (CV).

2. Landmarks:
a. Internal: Cephalic vein and distal biceps tendon. The nerve is lateral to the distal biceps
tendon.
3. Relevant anatomy: The LABC nerve is the terminal sensory branch of the musculocutaneous
nerve. It branches out from the musculocutaneous nerve, piercing the deep fascia at the level
proximal to the elbow joint to lie lateral to the distal biceps tendon. It runs along the cephalic
vein and divides distally into the ventral and dorsal branches that supply the lateral and posterior aspects of the forearm up to the wrist.
4. Points to remember: The LABC nerve can be injured due to injury to the cephalic vein (eg, during venipuncture) or due to distal biceps tendon tears due to its close proximity to the cephalic
vein and distal biceps tendon.8

254

Chapter 8

Medial Antebrachial Cutaneous Nerve
1. Probe/patient position: The probe is placed in the sagittal oblique axis on the axillary fossa. The
medial antebrachial cutaneous (MABC) nerve is seen above the axillary artery and vein, close
to the ulnar and median nerves (Figure 8-26). The MABC nerve can be followed distally as it
travels with the basilic vein between the brachialis and triceps brachii muscles (Figure 8-27).8

A

B

Figure 8-26. MABC nerve. (A) Probe placement in the sagittal oblique axis on the axillary fossa. (B) The MABC nerve
(white arrow) is seen above the axillary artery (red A) and vein (blue V).

A

B

Figure 8-27. The MABC nerve with the basilic vein distally at the mid-arm level. (A) Probe placement. (B) The MABC
nerve (yellow arrow) with the basilic vein (BV) and ulnar nerve (white arrow).

2. Landmarks: Axillary artery in the axillary fossa; basilic vein in the arm
3. Relevant anatomy: The MABC nerve is derived from the medial cord of the brachial plexus.
It pierces the brachial fascia and courses at the ulnar aspect of the brachial artery and along
the basilic vein.

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255

Posterior Antebrachial Cutaneous Nerve
1. Probe/patient position: The probe is placed on the posterior aspect of the mid-arm in SX orientation. The radial nerve is seen under the lateral head of the triceps muscle. Following the
radial nerve distally, the posterior antebrachial cutaneous (PABC) nerve is seen leaving the
radial nerve and is seen subcutaneously (Figure 8-28).8

A

B

C

Figure 8-28. PABC nerve. (A) Probe
placement on the posterior aspect
of the mid-arm in the SX orientation
to visualize the radial nerve. The
radial nerve is followed distally to
visualize the PABC nerve leaving the
radial nerve and travelling lateral and
superficial. (B) The radial nerve (white
arrow) is seen under the lateral head of
the triceps muscle. (C) The PABC nerve
(white arrow) is in close proximity to
the lateral epicondyle. Accompanying
blood vessel can be seen (red area).

2. Landmarks: Radial nerve and lateral head of the triceps
3. Relevant anatomy: The PABC nerve is a branch of the radial nerve. It branches from the main
trunk of the radial nerve at the outlet of the spiral groove. It travels between the lateral head
of the triceps and the brachialis muscle and then emerges subcutaneously, giving anterior and
posterior branches to supply the posterolateral aspect of the forearm.
4. Points to remember: The PABC nerve is in close proximity to the lateral epicondyle and should
be examined in cases of chronic lateral epicondylitis or recalcitrant lateral epicondylitis.8

256

Chapter 8

Ulnar Nerve
1. Probe/patient position: The probe is placed in the SX over the ulnar nerve at the medial elbow,
bridging the medial epicondyle and the olecranon process (Figure 8-29). The ulnar nerve is
closer to the medial epicondyle bony landmark. The ulnar nerve can be followed proximally
where it lies just above the medial triceps muscle. It can be followed distally in the true cubital
tunnel as it travels between the 2 heads of the flexor carpi ulnaris (FCU) muscle (see Figures
3-19 and 3-20).

A

B

Figure 8-29. Ulnar nerve. (A) Probe
placement in the SX over the ulnar nerve
at the medial elbow, bridging the medial
epicondyle and olecranon process. (B)
SX view of the ulnar nerve (white arrow)
showing the medial epicondyle (ME)
and olecranon (OL).

2. Landmarks: The medial epicondyle and olecranon are bony landmarks. The 2 heads of the
FCU muscle are internal landmarks for scanning the nerve distal to the medial epicondyle in
the true cubital tunnel.
3. Relevant anatomy: The ulnar nerve travels along the medial aspect of the arm and overlies the
medial triceps as it approaches posterior to the medial epicondyle. The fascia of the medial
triceps brachii and the intermuscular septum form Osborne’s fascia, which covers the ulnar
nerve at the level proximal to the medial epicondyle. Just distal to the medial epicondyle, the
ulnar nerve is covered by the arcuate ligament, which forms the roof of the cubital tunnel
between the humeral and ulnar heads of the FCU muscle.9
4. Points to remember: The ulnar nerve should be scanned with the elbow in about 60 to
70 degrees of flexion. Scanning the nerve in 90 degrees or more of elbow flexion is not recommended because it has been reported that 20% of the asymptomatic population may have
ulnar nerve dislocation, and at 90 degrees of flexion the ulnar nerve may be at the apex of the
medial epicondyle or anterior to the medial epicondyle.10

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257

Radial Nerve and Its Branches
1. Probe/patient position: The probe is positioned on the radial aspect of the anterior elbow
crease in SX orientation. The radial nerve is located between the brachialis and brachioradialis
muscles. The radial nerve is followed distally where it divides into the superficial and deep
branches of the radial nerve (Figure 8-30).

A

B

Figure 8-30. Radial nerve. (A) Probe placement on the radial aspect of the
anterior elbow crease in SX orientation. (B) The radial nerve is visualized
between the brachialis (BR) and brachioradialis (BrD) muscles. Also shown are
the superficial branch (yellow arrow) and deep branch (white arrow).

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Chapter 8
The superficial branch of the radial nerve is seen branching out from the medial aspect of
the radial nerve and descending underneath the brachioradialis muscle.8 Distally, the superficial branch pierces the antebrachial fascia between the extensor carpi radialis longus and
brachioradialis tendons, approximately 10 cm proximal to the anatomical snuff box, and then
runs the dorsal-radial aspect of hand to give sensory innervation of the dorsal-radial aspect of
the hand up to the radial aspect of the fourth digit (Figure 8-31).

A

B

Figure 8-31. Superficial branch of the radial nerve. (A) Probe placement.
(B) Superficial branch of the radial nerve (yellow arrow) and overlying
brachioradialis muscle (BrD).

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259

The deep branch passes through the arcade of Frohse between the 2 heads of the supinator
muscle to pass dorsally, where it becomes the posterior interosseous nerve supplying other
extrinsic wrist extensor muscles (Figure 8-32).

A

B

Figure 8-32. Deep branch of the radial
nerve. (A) Probe placement. (B) Deep
branch of the radial nerve (yellow
arrow) between the superficial head
(SS) and the deep head (DS) of the
supinator muscle. (R = radius.)

2. Landmarks: Brachialis and brachioradialis muscles to locate the main trunk of the radial
nerve at the anterior elbow crease; 2 heads of the supinator muscle to locate the deep branch
3. Relevant anatomy: The main trunk of the radial nerve at the elbow divides into 2 branches:
the superficial branch, which branches out from the medial aspect of the main trunk, and the
deep branch, which enters the arcade of Frohse to pass between the 2 heads of the supinator
muscle to become the posterior interosseous nerve. The deep branch gives motor innervation to the supinator and extensor carpi radialis brevis muscles before entering the arcade
of Frohse. The posterior interosseous nerve supplies all the extrinsic wrist extensor muscles
except the extensor carpi radialis longus. Distally, the posterior interosseous nerve gives sensory supply to the dorsal wrist capsule.
4. Points to remember: In suspected cases of radial tunnel syndrome, the radial nerve should
be checked in SX and LX view as it enters the arcade of Frohse. Focal compression may be
evident as an hour-glass deformity or a focal constriction of the nerve as it enters the arcade
of Frohse. Other causes of focal neuropathy include ganglion cyst, soft tissue masses, or other
space occupying lesions.

260

Chapter 8

Median and Anterior Interosseous Nerves
1. Probe/patient position: The probe is placed on the anteromedial aspect of the elbow crease in
SX orientation. The median nerve is seen between the brachialis and pronator teres muscles,
medial to the brachial artery (Figure 8-33). The median nerve can be followed distally where
it travels between the humeral and ulnar heads of the pronator teres. The brachial artery at
this point divides into the radial and ulnar arteries, with the ulnar artery deep to the ulnar
head of the pronator teres muscles and the median nerve on the medial aspect of the ulnar
artery. In the mid-forearm, the median nerve leaves the ulnar artery and travels in the fascial
plane between the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS)
muscles, where it is easy to locate (Figure 8-34).9

A

B

Figure 8-33. Median nerve. (A) Probe placement on the anteromedial aspect
of the elbow crease in the SX orientation. (B) The median nerve (white arrow)
is visualized between the brachialis (BR) and pronator teres (PrTr) muscles,
medial to the brachial artery (white A).

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261

Figure 8-34. Median nerve (yellow
arrow) between the fascial planes
of the FDP and FDS muscles.

The anterior interosseous nerve (AIN) branching pattern is variable. The AIN can branch
off from the posterior aspect to the posteromedial aspect of the main median nerve at the level
proximal or distal to the pronator teres muscle.11
2. Landmarks: Brachial artery, brachialis muscle, and pronator teres muscle for median nerve
localization at the anterior elbow
3. Relevant anatomy: The median nerve innervates all the forearm flexors except the FCU
muscle and the ulnar aspect of the FDP muscle, with no sensory supply to the forearm. The
AIN emerges from the posterior aspect of the median nerve at the elbow level with a variable
branching pattern, which may be proximal or distal to the pronator teres level. Distally, the
AIN lies between the flexor pollicis longus (FPL) muscle laterally and FDP muscle medially,
sending motor innervation to these muscles. It follows along the anterior interosseous artery
and rests on the anterior surface of the interosseous membrane to give motor innervation to
the pronator quadratus distally and sensory innervation to the volar wrist joint capsule.11
4. Points to remember: The AIN can be compressed by the fibrous arch of the pronator teres, the
fibrous arch of the FDS muscle, and Gantzer’s muscle when hypertrophied and anterior to the
AIN. The median nerve can be compressed by the ligament of Struthers.9,11

262

Chapter 8

Wrist, Hand, and Digits
Median Nerve
1. Probe/patient position: The probe is placed in the SX view with the pisiform as the internal
landmark. The median nerve is visualized in the carpal tunnel with 9 tendon slips: 4 slips of
the FDP muscle, 4 slips of the FDS muscle, and 1 slip of the FPL muscle (Figure 8-35).

A

B

Figure 8-35. Median nerve at the wrist. (A) Probe placement. (B) SX view of the median nerve (white arrow), with the
pisiform (P) as an internal landmark.

2. Landmarks:
a. External: Pisiform
b. Internal: Pisiform, scaphoid bone, flexor retinaculum, and flexor tendons. Mean crosssectional area of the median nerve is 9 mm2 at the pisiform-scaphoid level.12
3. Relevant anatomy: The median nerve enters the hand through the fibro-osseous tunnel or
carpal tunnel. The roof of the carpal tunnel is formed by the flexor retinaculum, and the floor
of the carpal tunnel is formed by the carpal bones.
4. Points to remember: Tilting the probe will make the tendons of the carpal tunnel appear
darker in one direction and brighter in other direction as tendons exhibit a greater degree
of anisotropy. This maneuver will help differentiate the nerve, which is hypoechoic and less
prone to anisotropy artifact, from the tendons.

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263

Palmar Cutaneous Branch of the Median Nerve
1. Probe/patient position: The median nerve is localized at the carpal tunnel region and then
traced proximally to the distal forearm level (approximately 5 cm proximal to the wrist
crease). In the distal forearm, the palmar cutaneous nerve branches off from the median
nerve. It travels distally into the palm, passing superficial to the flexor retinaculum and just
medial to the flexor carpi radialis (FCR) tendon (Figure 8-36).

A

B

Figure 8-36. (A) Palmar cutaneous nerve (yellow arrow) splitting from the median nerve
(white triangle) in the distal forearm. (B) Palmar cutaneous branch of the median nerve
(yellow arrow) passing superficial to the flexor retinaculum (white arrows) and just medial to
the FCR tendon. (MN = median nerve.)

2. Landmarks: Median nerve in the carpal tunnel and FCR tendon
3. Relevant anatomy: The palmar cutaneous branch arises from the radial border of the median
nerve and provides sensory innervation to the skin of the radial aspect of the palm.9 After
branching off, it travels with the median nerve for 2 to 3 cm and then runs along the ulnar
aspect of the FCR tendon.

264

Chapter 8

Ulnar Nerve
1. Probe/patient position: The probe is placed in the SX view at the level of the pisiform bone. The
ulnar nerve is visualized immediately radial to the pisiform bone. The ulnar artery is visualized radial to the ulnar nerve (Figure 8-37).
Figure 8-37. Ulnar nerve (white
arrow) at the wrist with the ulnar
artery (red arrow) radial to it and
the pisiform (P) as an internal
landmark.

2. Landmarks:
a. External: Pisiform
b. Internal: Ulnar artery
3. Relevant anatomy: The ulnar nerve enters the hand through Guyon’s canal with the ulnar
artery and vein. Guyon’s canal is formed by the pisiform medially and the hook of the hamate
laterally. The floor is formed by the flexor retinaculum, and the root is formed by the palmar
carpal ligament and palmaris brevis muscle.9

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265

Dorsal Ulnar Cutaneous Nerve
1. Probe/patient position: The probe is placed transversely on the volar-ulnar aspect of the distal
third of the forearm to locate the ulnar nerve under the FCU muscle. Following the ulnar nerve
distally, the dorsal cutaneous nerve can be seen branching off from the medial aspect of the
ulnar nerve8 at about 6 cm proximal to the distal aspect of the head of the ulna (Figure 8-38).

A

B

Figure 8-38. Dorsal ulnar cutaneous nerve. (A) Probe placement transversely
on the volar-ulnar aspect of the distal third of the forearm to locate the ulnar
nerve under the FCU muscle. (B) The dorsal cutaneous nerve (yellow arrow)
can be seen branching off from the medial aspect of the ulnar nerve (white
arrow).

2. Landmarks: Ulnar nerve and FCU muscle at the distal third of the forearm
3. Relevant anatomy: The dorsal ulnar cutaneous nerve arises from the ulnar nerve and courses
distally, piercing the deep fascia to move dorsally to innervate the skin of the dorsoulnar
aspect of hand, dorsal aspect of the fifth digit, and dorsoulnar aspect of the fourth digit of
the hand.

266

Chapter 8

Digital Nerves
1. Probe/patient position: The probe is placed in SX orientation on the volar aspect of the digit.
The palmar digital nerve and blood vessel bundle can be seen on either side of the flexor tendons as the radial and ulnar digital nerves and blood vessel bundle (Figure 8-39).

A

B

Figure 8-39. Digital nerves. (A) Probe placement. (B) The palmar digital nerve (white arrows) and blood vessel (red
areas) bundle can be seen on the either side of the flexor tendons (FT).

2. Landmark: Accompanying blood vessels with digital nerves on color Doppler
3. Points to remember: Digital nerves can be scanned from proximal to distal as they branch out
from median and ulnar nerves into smaller digital branches.

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267

LOWER EXTREMITY NERVES
Hip and Pelvic Region
Lateral Femoral Cutaneous Nerve
1. Probe/patient position: The probe is placed at the anterior superior iliac spine (ASIS) to visualize the lateral femoral cutaneous nerve (LFCN; Figure 8-40). The nerve is then traced distally
as it passes beneath the inguinal ligament and courses anterolateral to the sartorius muscle,
where it divides into anterior and posterior branches (Figure 8-41).8

A

Figure 8-40. LFCN. (A) Probe
placement. (B) The LFCN (white arrow)
medial to the ASIS.

Figure 8-41. The LFCN (white
arrow) slightly distal to the
inguinal ligament, where it can
be seen overlying the sartorius
muscle.

B

268

Chapter 8

2. Landmarks:
a. Internal: Inguinal ligament and sartorius muscle
b. External: ASIS
3. Relevant anatomy: The LFCN originates from the lumbar plexus and L2 and L3 spinal nerves.
It courses inferiorly and laterally on the iliacus muscle before it reaches the medial aspect of
the ASIS. The LFCN runs under the inguinal ligament between 2 fascial planes: fascia iliaca
and fascia latae. It then runs in the fat compartment anterior and lateral to the sartorius
muscle.8 It gives sensory innervation to the skin of the anterolateral aspect of the thigh.
4. Points to remember: The LFCN is a very small nerve and may require a higher frequency probe
in the range of 18 to 20 megahertz (MHz).

Ilioinguinal and Iliohypogastric Nerves
1. Probe/patient position: The probe is placed at a level 5 cm proximal to the ASIS in an orientation perpendicular to the iliac crest, with the lateral end of the probe resting on the iliac crest.
Between the transverse abdominis and internal oblique muscles, the ilioinguinal nerve is seen
medial to the iliac crest and the iliohypogastric nerve is seen 1 cm medial to the ilioinguinal
nerve (Figure 8-42).4,13

A

B

Figure 8-42. Ilioinguinal and iliohypogastric nerves. (A) Probe placement. (B) Ilioinguinal (white arrow) and
iliohypogastric (yellow arrow) nerves between the transverse abdominis (TA) and internal oblique (IO) muscles.
(EO = external oblique muscle.)

2. Landmarks:
a. External: ASIS
b. Internal: External oblique, internal oblique, and transverse abdominis muscles
3. Relevant anatomy: The ilioinguinal and iliohypogastric nerves arise from the anterior ramus
of the L1 spinal root. The ilioinguinal nerve gives cutaneous innervation to the superior
medial thigh. In males, it gives innervation to the skin over the anterior third of the scrotum
and the root of the penis. In females, it innervates the anterior one-third of the labia majora
and the root of the clitoris. The ilioinguinal nerve gives motor branches to the internal oblique
and transverse abdominis muscles. The iliohypogastric nerve gives cutaneous innervation to
the posterolateral gluteal region and pubic region.
4. Points to remember: The ilioinguinal nerve may form a common trunk with the iliohypogastric nerve in 20% of cases.14

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269

Pudendal Nerve
1. Probe/patient position: The probe is placed in the SX at the level of the lesser sciatic notch of
the ischium. The pudendal nerve is seen overlying the curved course of the obturator internus
muscle, which overlies the ischium (Figure 8-43).4

A

C

B

Figure 8-43. Pudendal nerve. (A and C) Probe placement and relevant
anatomy. (B) The probe is placed in the SX at the level of the lesser sciatic
notch of the ischium. The pudendal nerve (yellow arrow) overlies the curved
course of the obturator internus muscle, which overlies the ischium. Also
shown is the sciatic nerve (white arrow).

2. Landmarks: Ischial spine to locate the lesser sciatic notch level; curved course of the obturator
internus muscle over the ischium as an internal landmark
3. Relevant anatomy: The pudendal nerve arises from the S2, S3, and S4 nerve roots of the anterior division of the sacral plexus and is the nerve of the perineum.

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Chapter 8

Femoral and Saphenous Nerves
1. Probe/patient position: The probe is placed along the inguinal ligament, and the femoral artery
is identified as an anechoic pulsatile structure (Figure 8-44). Lateral to the femoral artery, the
femoral nerve appears as a hyperechoic triangular structure.

B

A

Figure 8-44. Femoral nerve. (A) Probe
placement and relevant anatomy.
(B) Femoral nerve (white arrow) and
femoral artery (white A).

For the saphenous nerve, the probe is placed in the SX in the femoral triangle region. The
saphenous nerve is seen accompanied by the femoral artery, deep to the sartorius muscle, medial
to the vastus medialis muscle, and superficial to the adductor longus muscle (Figure 8-45).15

A

B

Figure 8-45. Saphenous nerve in the femoral triangle area. (A) Probe placement. (B) Saphenous nerve (yellow arrow)
accompanied by the femoral artery (red A), deep to the sartorius muscle, medial to the vastus medialis muscle (VM),
and superficial to the adductor longus muscle (AL).

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271

2. Landmarks: Femoral artery in the inguinal canal for femoral nerve localization; femoral
artery, sartorius muscle, vastus medialis muscle, and adductor longus muscle in the femoral
triangle for saphenous nerve localization
3. Relevant anatomy: The femoral nerve exits the pelvis into the anterior compartment of the
thigh after passing beneath the inguinal ligament. The femoral nerve divides into the motor
and sensory branches 2 to 3 cm distal to the inguinal ligament. The sensory branch of the
femoral nerve is the saphenous nerve, which innervates the skin of the anteromedial thigh,
anteromedial knee, and medial leg.15

Obturator Nerve
1. Probe/patient position: The probe is placed along the inguinal ligament, medial to the femoral artery, over the pectineus muscle with the probe oriented superiorly and dorsally (tilt the
probe). The obturator nerve is seen between the pectineus muscle superiorly and the obturator
externus muscle inferior to the nerve (Figure 8-46).

A

Figure 8-46. Obturator nerve. (A)
Probe placement along the inguinal
ligament, medial to the femoral artery,
and over the pectineus muscle, with the
probe oriented superiorly and dorsally
(tilt the probe). (B) Obturator nerve
(white arrow) between the pectineus
muscle superiorly and the obturator
externus muscle inferior to the nerve.

B

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Chapter 8
The probe is then moved distally to visualize the anterior and posterior divisions of the
nerves. The probe orientation is in the SX without any tilt because the nerve branches are anterior between the adductor group of muscles. Anterior division is seen in the SX between the
adductor longus and adductor brevis muscles. Posterior division is seen between the adductor
brevis and adductor magnus muscles (Figure 8-47).

Figure 8-47. Obturator nerve
anterior (white arrow) and
posterior (yellow arrow) divisions
between the adductor group
of muscles: adductor longus
(AL), adductor brevis (AB), and
adductor magnus (AM).

2. Landmarks:
a. External: Inguinal ligament and femoral artery
b. Internal: Pectineus muscle, obturator externus muscle, and superior and inferior pubic
rami; adductor longus, adductor brevis, and adductor magnus muscles for the anterior and
posterior divisions
3. Relevant anatomy: The obturator nerve arises from L2-L4. It enters the thigh through the
obturator canal. The anterior branch innervates the adductor longus, adductor brevis, and
gracilis muscles. The posterior branch innervates the adductor brevis, adductor magnus, and
obturator externus muscles.

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273

Sciatic Nerve
1. Probe/patient position: The probe is placed along the piriformis muscle to visualize the sciatic
nerve as a hyperechoic structure under the piriformis muscle belly (Figure 8-48). The probe
is then moved distally to visualize the sciatic nerve overlying the quadratus femoris muscle
(Figure 8-49).

A

B

Figure 8-48. Sciatic nerve. (A) Probe
placement. (B) Piriformis muscle (white
arrow), sciatic nerve (yellow arrow), and
greater trochanter (GT).

A

Figure 8-49. Sciatic nerve overlying
the quadratus femoris muscle. (A)
Probe placement and relevant
anatomy. (B) The sciatic nerve (yellow
arrow) overlying the quadratus femoris
muscle (QF).

B

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Chapter 8

2. Landmarks:
a. External: Greater trochanter to identify the distal part of the piriformis, which is then
traced medially to identify the sciatic nerve running under it.
b. Internal: LX view of the piriformis muscle. Moving the probe distally, the nerve is lateral to
the ischial tuberosity and superficial to the quadratus femoris muscle.
3. Relevant anatomy: The sciatic nerve is the largest nerve of the body, with root supply from
L4-S3. It supplies the posterior muscles of the thigh, lower leg, and foot. It provides sensory
innervation to the leg and foot, except the medial aspect.

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275

Knee and Lower Leg Region
Tibial and Common Fibular Nerves and Their Branches
1. Probe/patient position: The probe is placed in the SX on the posterior aspect of the knee to
visualize the hyperechoic sciatic nerve accompanied by the popliteal artery and vein. The
sciatic nerve is then followed distally to see the nerve dividing into the tibial and common
fibular branches (Figure 8-50).

A

Figure 8-50. Tibial and common
fibular nerves. (A) Probe placement.
(B) Hyperechoic sciatic nerve (white
arrow) on the posterior aspect of the
knee. (C) Sciatic nerve splitting into
the tibial (white arrow) and common
fibular (yellow arrow) nerves.

B

C

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Chapter 8
The tibial nerve runs deep on the posterior aspect of the leg. The fibular nerve moves laterally and has a superficial course as it wraps around the fibular neck to divide into the deep and
superficial fibular nerves (Figure 8-51). The superficial fibular nerve passes deep between the
peroneal muscles to give motor supply to the peroneus longus and peroneus brevis muscles.

A

B

Figure 8-51. Common fibular nerve at the fibular neck. (A) Probe placement.
(B) Common fibular nerve (white arrow) at the fibular neck area.

2. Landmarks: Sciatic nerve, popliteal artery, and vein
3. Relevant anatomy: The sciatic nerve divides into the tibial and common peroneal nerves at the
apex of the popliteal fossa.
4. Points to remember: There is variation in the branching levels of the sciatic nerve. If the sciatic
nerve trunk is not found at the apex of the popliteal fossa, the probe can be moved proximally
to locate the common nerve trunk.

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277

Sural Nerve
1. Probe/patient position: The probe is positioned in the SX view in the posterior aspect of the
lower leg at the level of the musculotendinous junction of the Achilles tendon or 14 cm proximal from the lateral malleolus. The sural nerve is seen accompanied by the lesser saphenous
vein subcutaneously, overlying the tendinous portion of the Achilles (Figure 8-52). The sural
nerve can be traced distally as it branches into smaller sensory branches or proximally where
it is formed by the medial sural cutaneous nerve (MSCN) and lateral sural cutaneous nerve
(LSCN).

A

B

Figure 8-52. Sural nerve. (A) Probe placement in the SX view in the posterior
aspect of the lower leg at the level of the musculotendinous junction of the
Achilles tendon or 14 cm proximal from the lateral malleolus. (B) The sural
nerve (white arrow) is seen accompanied by the lesser saphenous vein (LSV)
subcutaneously, overlying the tendinous portion (red arrow) of the Achilles.

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Chapter 8

2. Landmark: Lesser saphenous vein
3. Relevant anatomy: The sural nerve is formed by the MSCN and LSCN. The MSCN originates
from the tibial nerve at the popliteal fossa, and the LSCN originates from the common fibular
nerve (Figure 8-53). The MSCN and LSCN merge together in the mid-calf to form the sural
nerve.8,16
Figure 8-53. The MSCN (white
arrow) originates from the tibial
nerve (white triangle) at the
popliteal fossa, and the LSCN
(yellow arrow) originates from
the common fibular nerve (yellow
triangle). The MSCN and LSCN
merge together in the mid-calf to
form the sural nerve.

4. Points to remember: To locate the sural nerve at the distal level, very light pressure with the
probe is required because more pressure will obliterate the lesser saphenous vein, which is a
landmark for visualization of the sural nerve.

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279

Saphenous Nerve
1. Probe/patient position: The probe is placed in the SX view on the medial aspect of the thigh at
the adductor canal. The saphenous nerve is seen as a hyperechoic structure next to the femoral
artery and vein, with the sartorius muscle above it, the vastus medialis muscle lateral to it, and
the adductor longus muscle deep to it. As the saphenous nerve is followed distally, it gives an
infrapatellar branch at the medial and distal aspect of the patella and a sartorial branch that
descends along the medial tibia to the ankle and is accompanied by the greater saphenous vein
(Figure 8-54).8,16

A

B

Figure 8-54. Saphenous nerve at the distal leg. (A) Probe placement on the medial aspect of the tibia in the lower leg.
(B) Saphenous nerve (white arrow) along the medial tibia, accompanied by the greater saphenous vein (GSV).

2. Landmarks: Femoral artery and vein proximal to the knee level and greater saphenous vein
distal to the knee joint
3. Relevant anatomy: The saphenous nerve is the terminal sensory branch of the femoral nerve.
4. Points to remember: To locate the saphenous nerve distally, use very light pressure with the
probe because more pressure will obliterate the greater saphenous vein, which is a landmark
for visualization of the saphenous nerve.

280

Chapter 8

Ankle and Foot Region
Deep Peroneal Nerve
1. Probe/patient position: The probe is placed in the SX view on the anterior aspect of the ankle.
The deep peroneal nerve is seen deep to the tendons and just above the talus. It is accompanied
by the dorsalis pedis artery (Figure 8-55).

A

B

Figure 8-55. Deep peroneal nerve. (A) Probe placement. (B) The deep peroneal nerve (white arrow) is seen deep to
the anterior tendons of the ankle and just above the talus. It is accompanied by the dorsalis pedis artery (white A).
(EHL = extensor hallucis longus muscle; TA = tibialis anterior.)

2. Landmarks: Dorsalis pedis artery and talar bony surface under it
3. Relevant anatomy: After branching off from the common peroneal nerve, the deep peroneal
nerve passes deep to the extensor digitorum longus (EDL) muscle and courses distally on the
anterior aspect of the interosseous membrane. At the ankle, it passes through the anterior
tarsal tunnel. Due to the sharper turn of the deep peroneal nerve around the fibular neck to
enter the anterior aspect, it is tethered more to the fibula than the superficial peroneal nerve,
and therefore more susceptible to compression.

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281

Superficial Peroneal Sensory Nerve
1. Probe/patient position: The probe is placed on the anterolateral aspect of the leg about 10 to
12 cm proximal to the lateral malleolus. The superficial peroneal nerve lies between the EDL
and peroneus longus muscles (Figure 8-56).16

A

B

Figure 8-56. Superficial peroneal sensory nerve. (A) Probe placement. (B)
The superficial peroneal nerve (white arrow) lies between the EDL and
peroneus longus (PL) muscles.

2. Landmarks: Peroneus longus and EDL muscles

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Chapter 8

Tibial Nerve at the Tarsal Tunnel and Its Branches
1. Probe/patient position: The probe is placed on the medial aspect of the ankle with the medial malleolus as a bony landmark to visualize the tarsal tunnel structures in the SX view. The posterior
tibial nerve at the medial ankle is a hyperechoic structure accompanied by the artery and vein
(Figure 8-57).
A

B

Figure 8-57. Tibial nerve at the
tarsal tunnel/medial ankle. (A) Probe
placement. (B) The posterior tibial
nerve (white arrow) is visualized as a
hyperechoic structure accompanied by
the artery (white A) and vein (V). Also shown are the tibialis posterior (TP), flexor digitorum longus (FDL), and flexor
hallucis longus (FHL) muscles and the medial malleolus (MM) as an internal landmark.

2. Landmarks: Medial malleolus as an internal landmark. The tibial nerve divides into the medial plantar, lateral plantar, and medial calcaneal branches (Figure 8-58). The medial calcaneal
branch has a variable branching pattern and may branch out from the tibial nerve at the level
proximal to the tarsal tunnel.16
Figure 8-58. The tibial nerve divides
into the medial plantar (white arrow),
lateral plantar (yellow arrow), and
medial calcaneal branches (red
arrow).

3. Relevant anatomy: From anterior to posterior, structures in the tarsal tunnel are arranged
as the tibialis posterior, flexor digitorum longus (FDL) muscle, posterior tibial artery, nerve,
vein, and flexor hallucis longus (FHL) muscle. Distally, the tibial nerve branches into the
medial plantar, lateral plantar, and medial calcaneal branches.
4. Points to remember: There is great variability in the branching pattern of the posterior tibial
nerve.17

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283

Medial Plantar Nerve
1. Probe/patient position: The probe is positioned over the medial ankle to localize the tibial
nerve, which is then followed distally to locate the medial plantar nerve. On the medial aspect
of the foot, the medial plantar nerve is visualized between the abductor hallucis muscle and
knot of Henry (FDL and FHL intersection; Figure 8-59). On the plantar aspect of the foot,
the medial plantar nerve accompanied by the medial plantar artery is visualized between the
flexor hallucis brevis and quadratus plantae muscles.15,16

A

B

Figure 8-59. Medial plantar nerve.
(A) Probe placement. (B) The medial
plantar nerve (small white arrow),
accompanied by the medial plantar
artery (red arrow), is visualized between
the abductor hallucis muscle and knot
of Henry (FDL and FHL intersection;
large white arrow).

2. Landmark: Medial plantar artery
3. Relevant anatomy: The medial plantar nerve provides motor innervation to the flexor digitorum brevis, flexor hallucis brevis, abductor hallucis longus, and medial lumbrical muscles.
It provides sensory cutaneous innervation to the medial aspect of the plantar foot and toes.

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Chapter 8

Lateral Plantar Nerve
1. Probe/patient position: The probe is positioned over the medial ankle to localize the tibial
nerve, which is then followed distally to locate the lateral plantar nerve. The lateral plantar nerve and first branch of the lateral plantar nerve, or Baxter’s nerve, are best visualized
through the acoustic window of the abductor hallucis muscle (Figures 8-60 and 8-61).

A

B

Figure 8-60. Lateral plantar nerve. (A) Probe placement. (B) Lateral plantar nerve (white arrow), lateral plantar artery
(red arrow), and quadratus plantae (QP) muscle.

A

Figure 8-61. First branch of the lateral
plantar nerve, or Baxter’s nerve. (A)
Probe placement. (B) Baxter’s nerve
(white arrow) between the abductor
hallucis (AH) and quadratus plantae
(QP) muscles. (C = calcaneus.)

B

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285

2. Landmark: Lateral plantar artery
3. Relevant anatomy: The lateral plantar nerve provides motor innervation to all the intrinsic foot
muscles except for the muscles supplied by the medial plantar nerve. The lateral plantar nerve
travels with the lateral plantar artery as it courses medial to lateral. On the plantar aspect of
the foot, it is seen between the flexor digitorum brevis and quadratus plantae muscles. After
emerging from the lateral plantar nerve, the first branch of the lateral plantar nerve, or inferior
calcaneal nerve or Baxter’s nerve, passes between the abductor hallucis and quadratus plantae
muscles. As it travels laterally, it passes between the anterior aspect of the medial tubercle of
the calcaneus and flexor digitorum brevis muscle–aponeurosis complex.16,18
4. Points to remember: Visualization of the first branch of the lateral plantar nerve is challenging
due to its size, which is in the range of 1 to 2 mm,15,18 and due to the thicker skin of the plantar
aspect of the heel. The abductor hallucis muscle serves as a good acoustic window to visualize
the lateral plantar nerve and the first branch of the lateral plantar nerve.

286

Chapter 8

Digital Nerves
1. Probe/patient position: The probe is positioned in the SX at the intermetatarsal space. The digital nerves are visualized as hyperechoic structures accompanied by artery and vein bundles on
either side of the metatarsal (Figure 8-62).
A

B

C

D

Figure 8-62. Digital nerves (white arrows) on the dorsal and plantar aspects of the foot. (A) Probe placement
for dorsal digital nerve. (B) Dorsal digital nerve (white arrow). (C) Probe placement for plantar digital nerve. (D)
Plantar digital nerves (white arrows). (red areas = blood vessels.)

2. Landmarks: Digital artery and vein
3. Relevant anatomy: The digital nerves originate from the medial or lateral plantar nerves.

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287

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Financial Disclosures

Dr. Gina A. Ciavarra has no financial or proprietary interest in the materials presented herein.
Dr. Dimitrios Kostopoulos has no financial or proprietary interest in the materials presented herein.
Dr. Kornelia Kulig has no financial or proprietary interest in the materials presented herein.
Dr. Mukund Patel has no financial or proprietary interest in the materials presented herein.
Dr. Mohini Rawat has no financial or proprietary interest in the materials presented herein.

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