Applied Radiological Anatomy

Boundaries of axilla; Chapter 15: The upper limb
Inlet
Fig. 15.21 Line diagrams of the axilla and axilla
Anterior wall contents.
Floor
Axillary sheath
Medial wall containing a.,
Posterior wall v., n. and
lymphatics
Lateral wall
Axilla

A

Pectoralis major m. Biceps brachii m.
Pectoralis minor m. Humerus
Deltoid m.
Aorta Coracobrachialis m.
Left lung Triceps brachii m.
(lateral head)
Subscapularis m. Axillary a. and v.
Axilla
B Latissimus dorsi m.
Scapula
Pectoralis major m. Infraspinatus m.
Pectoralis minor m.
Biceps brachii m.
Axilla Humerus
Left lung Coracobrachialis m.
Deltoid m.
Subscapularis m. Axillary a. and v.
Triceps brachii m.
Fig. 15.22 Axial CT left axilla (superior to inferior). (lateral head)
Latissimus dorsi m.
Scapula
Infraspinatus m.

291

Section 3: Upper and Lower Limb B
A

Clavicle

Scalenus Scalenus
medius m. anterior m.

Brachial plexus Clavicle
divisions Brachial plexus
divisions
Brachial plexus Subclavian a.
trunks Subclavian v.
Subclavian a.
Subclavian v.

Brachial plexus divisions Musculo- Lateral Superior C5
Roots (anterior rami of C5-T1) cutaneous C6
Anterior C7
Trunks (superior, middle, inferior) Median C8
Divisions (anterior, posterior) Anterior T1
Radial Posterior
Cords (medial, lateral, posterior) C5 Posterior Middle
Terminal n. C6
C7 Posterior
Clavicle C8 Ulnar
T1 Posterior
Subclavian
a. Medial Inferior

Anterior

Roots
Trunks
Divisions
Cords
Terminal n.

Fig. 15.23 (A) Coronal T1 MRI, both axillae; (B) sagittal oblique T1 • Fat pads separate the fibrous joint capsule from the synovial
MRI, right axilla. membrane:
· on a normal lateral radiograph, only the anterior fat
pad can be seen, closely applied to the anterior

Table 15.6

• Two protuberances, the medial and lateral epicondyles, Muscle Origin Insertion Action
lie in an extracapsular location (Fig. 15.27). Biceps brachii
Long head: Radial Flexes and
Elbow joint Coracobrachialis supraglenoid tuberosity; supinates
Brachialis tubercle of bicipital forearm;
• The elbow joint consists of three articulations all enclosed scapula aponeurosis of weak arm
by a common joint cavity, the radiocapitellar and Short head: medial forearm flexor
ulnatrochlear joints (allowing 150° flexion-extension) coracoid process
and proximal radio-ulnar joint (allowing 90° pronation- of scapula Middle 1/3 of Flexes and
supination). medial border of weakly
Tip of coracoid humerus adducts arm
• When fully extended, the long axis of the forearm lies process of
laterally at an angle to the long axis of the forearm, termed scapula Coronoid Flexes
the carrying angle. process and forearm
Anterior lower tuberosity of
half of humerus ulna

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Chapter 15: The upper limb

Clavicle

A Acromion of

scapula

Coracoid of B Acromion
scapula of scapula
Head of
humerus Clavicle

Glenoid fossa Coracoid
scapula of scapula

Greater
tuberosity of
humerus

Lesser Glenoid fossa
tuberosity of scapula
humerus

Diaphysis Head of
humerus humerus

Deltoid Diaphysis
tuberosity humerus

Lateral
supracondylar
ridge humerus

Medial
supracondylar
ridge humerus

Medial Capitellum
epicondyle humerus
humerus
Fig. 15.24 (A) AP radiograph, right humerus; (B) lateral radiograph, right
Trochlea humerus.
humerus
Lateral
epicondyle
humerus

Capitellum
humerus

Humerus

Anterior (flexor)
compartment

Posterior (extensor)
compartment

Intermuscular
septae

Deep fascia
Skin

Medial Lateral

Fig. 15.25 Axial T1 MRI right arm.

distal humerus as a well defined lucent Normal lines on the elbow radiograph
structure
• Anterior humeral line:
· an elbow joint effusion will displace the fat pads
outwards, making the posterior fat pad visible · the distal aspect of the humerus is angulated at 40–45°
and the anterior fat pad more prominent anteriorly relative to the diaphysis
(Fig. 15.28).
· as such, approximately 1/3 of the capitellum should lie
anterior to a line drawn along the anterior aspect of the
humeral diaphysis on a lateral radiograph

293

Section 3: Upper and Lower Limb
A

B Biceps brachii m.

Deltoid m. Coracobrachialis m.
Humerus
Triceps brachii m. Brachial a.
(lateral head) Basilic v.
Triceps brachii m. Radial n.
(long head) Triceps brachii m.
(medial head)

C

Cephalic v.

Musculocutaneous Biceps brachii m.
n. Median n.
Basilic v.
Brachialis m. Brachial a.
Median cutaneous n.
Humerus of forearm
Superior ulnar collateral
Profunda brachii a. a.
Superior ulnar
Radial n. collateral v.

Triceps brachii m. Triceps brachii m.
(lateral head) (medial head)

Triceps brachii m.
(long head)

Fig. 15.26 (A) Scout localizer image of the right arm. The levels that panels (B), (C) and (D) have been taken at are denoted here as UPPER, MID and LOWER. (B)
Axial T1 MRI, right arm (upper). (C) Axial T1 MRI, right arm (mid). (D) Axial T1 MRI, right arm (lower). (E) Diagram to show the course of the nerves of the arm in
relationship to the muscles.

294

Cephalic v. D Chapter 15: The upper limb

Brachioradialis m. Biceps brachii m.
Musculocutaneous
Radial n. n.
Extensor carpi radialis Median n.
Brachial a.
longus m. Brachialis m.
Humerus Basilic v.
Ulnar n.
Triceps brachii m.

E

Brachial plexus
Axillary n.

Musculocutaneous n.
Radial n.
Median n.
Ulnar n.

Fig. 15.26 (cont.)

295

Section 3: Upper and Lower Limb

Table 15.7 Origin Insertion Action
Long head: infraglenoid tubercle of scapula Extends forearm
Muscle Lateral head: upper half of posterior diaphysis of humerus By a common tendon into posterior part of
Triceps brachii Medial head: lower half of posterior diaphysis of humerus olecranon process of ulna

Table 15.8 Ossification centres at elbow joint

Capitellum Age at first appearance Ulnar nerve at the elbow
Radial head 1 yr
Internal (medial) epicondyle 5 yrs • Passes superficially through the medial elbow in the cubital
Trochlea 4–6 yrs tunnel, a fibro-osseous tunnel:
Olecranon 9–10 yrs
External (lateral) epicondyle 9–10 yrs · curved floor formed by groove between the olecranon
12 yrs process of the ulna and the medial epicondyle of the
humerus
· if less than 1/3 of the capitellum lies anterior to
the anterior humeral line, it is suggestive of a · proximal roof formed by the cubital tunnel
supracondylar fracture of the humerus. retinaculum (CTR), a thickening of fascia that bridges
the walls of the bony floor
• Radiocapitellar line:
· distal roof formed by the arcuate ligament (ligament
· a line drawn along the centre of the radial diaphysis of Osborne), an aponeurotic sheet connecting the
should intersect the capitellum on both the AP and heads of the flexor carpi ulnaris muscle and the distal
lateral elbow radiograph continuation of the CTR (Fig. 15.33).

· if this line does not intersect the capitellum, a radial Radial nerve at the elbow
head dislocation is likely (Fig. 15.29).
• Lies anterior to the lateral epicondyle of the humerus
Ossification at the elbow between the brachialis and brachioradialis muscles.
Although exact recall of the dates of ossification is not essential,
it is important to remember the order of ossification (CRITOE) • Gives off the posterior interosseous (deep motor) branch
as any apparent change in this order usually signifies a fracture and a superficial (sensory) branch.
(Fig. 15.30and Table 15.8).
• Posterior interosseous nerve enters the posterior
Cross-sectional anatomy compartment of the forearm between the heads of the
supinator muscle.
Elbow joint ligaments (Fig. 15.31)
• The joint capsule is thickened to form the radial (lateral) Cubital fossa (Fig. 15.34)

and ulnar (medial) collateral ligament complexes. • Triangular-shaped potential space in anterior elbow.
• Radial collateral ligament complex: • Permits passage of structures from the arm to the forearm.
• Base: imaginary horizontal line connecting the epicondyles
· provides varus stability
· consists of radial collateral ligament, annular of the humerus.
• Apex: point at which the borders of the brachioradialis and
ligament, accessory collateral ligament and lateral
ulnar collateral ligament. pronator teres muscles cross.
• Contents (from lateral to medial):
• Ulnar collateral ligament complex:
· biceps brachii tendon
· provides valgus stability · brachial artery, which divides into the radial and ulnar
· consists of three bundles: anterior (primary valgus
arteries
restraint), posterior and transverse (Fig. 15.32). · median nerve.

Median nerve at the elbow Forearm
• Located in the anterior cubital fossa, anterior to the Plain radiographic anatomy

brachialis muscle and deep to the bicipital aponeurosis. Radius and ulna
• Passes between the heads of the pronator teres muscle as it The radius and ulna are long triangular-shaped bones with
anterior, posterior and interosseous borders, the latter of
exits the cubital fossa. which allow attachment of the interosseous membrane which
• Gives off the anterior interosseous nerve branch near the connects the two bones.

bifurcation of the brachial artery. They are joined at the proximal and distal radio-ulnar
joints. The proximal radius is formed of the:
• head, for articulation with the capitellum of the humerus

and the coronoid process of the ulna at the elbow joint.

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A Chapter 15: The upper limb

Olecranon fossa humerus Humerus
Medial epicondyle humerus
Lateral epicondyle
Olecranon ulna humerus
Trochlea humerus Capitellum humerus
Coronoid process ulna Head radius
Neck radius
Ulna Tuberosity radius
Radius

B

Humerus

Trochlea humerus Capitellum humerus
Olecranon ulna Head radius
Tuberosity radius
Trochlear notch ulna Radius
Neck radius
Coronoid process ulna
Ulna

Fig. 15.27 (A) AP radiograph right elbow; (B) lateral radiograph right elbow.

The distal radius is formed of the:
• broad distal surface, for articulation with the carpal bones

at the wrist joint and with the distal ulna at the distal radio-
ulnar joint
• styloid process, which provides attachment for the
brachioradialis muscle and the radial collateral ligament of
the wrist joint.

The proximal ulna is formed of the:
• olecranon process with its trochlear fossa for articulation

with the trochlea of the humerus
• coronoid process, a proximal and lateral protuberance that

allows articulation with the radial head.

The distal ulna is formed of the:
• head for articulation with the carpal bones at the wrist joint

and with the distal radius at the radio-ulnar joint
• styloid process, which provides attachment for the ulnar

collateral ligament of the wrist joint.

Fig. 15.28 Lateral radiograph left elbow. The anterior fat pad (AFP) is elevated
and the posterior fat pad (PFP) is visible, both of which are abnormal and
indicate an underlying joint effusion displacing them outwards.

297

Section 3: Upper and Lower Limb B
A

Fig. 15.29 (A) AP radiograph right elbow; (B) lateral radiograph right elbow. The anterior humeral line (AHL) is a line drawn anterior to the humeral diaphysis. One-
third of the capitellum should lie anterior to it. The radiocapitellar line (RCL) should intersect the proximal radial diaphysis and the capitellum. The normal carrying
angle of 15–20° is the angle formed between the long axes of the arm and forearm.

Interosseous Oblique
membrane cord

Annular ligament Ulnar
Medial epicondyle collateral
ligament
Anterior part
Posterior part
Oblique part

Order of ossification - CRITOE;

Capitellum C

Radial head R Oblique Interosseous
cord membrane

Internal epicondyle I

Trochlea T Annular ligament
Radial collateral
Olecranon O
ligament
External epicondyle E
Olecranon
Fig. 15.30 Diagram to show the normal ossification centres at the elbow.
The centres ossify in the following chonological order CRITOE: Capitellum, Fig. 15.31 Diagram showing the intrinsic ligaments of the elbow.
Radial head, Internal (medial) epicondyle, Trochlea, Olecranon, External
(lateral) epicondyle.

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A Chapter 15: The upper limb

Cephalic v. Biceps brachii tendon

Brachioradialis m. Median n.
Radial n.
Brachial a.
Profunda brachii a.
Extensor carpi Basilic v.

radialis longus m. Brachialis m.

Lateral supracondylar Humerus
ridge humerus
Medial supracondylar
Triceps brachii m. ridge humerus
(lateral head) Ulnar n.

B Triceps brachii m.
(medial head)
Cephalic v.
Biceps brachii tendon
Brachioradialis m. Brachial a.
Median n.
Radial n. Basilic v.
Brachialis m.
Profunda brachii a. Pronator teres
Olecranon fossa
Extensor carpi humerus
radialis longus m. Common flexor tendon
Common extensor origin
Medial epicondyle
tendon origin humerus
Lateral epicondyle Ulnar n.
Cubital tunnel
humerus retinaculum
Anconeus

Olecranon ulna

C Pronator teres
Basilic v.
Biceps brachii tendon Ulna
Brachioradialis m. Flexor carpi radialis
Supinator m. m.
Brachialis m. Ulnar n.
Extensor carpi Flexor carpi ulnaris m.
radialis brevis m. (humeral head)
Extensor carpi Arcuate ligament
radialis longus m. Flexor carpi ulnaris m.
Radius (ulnar head)
Anconeus
Pronator teres
D Median n.
Basilic v.
Cephalic v. Extensor carpi radialis
Brachioradialis m. longus m.
Palmaris longus m.
Radial n. Flexor digitorum
Brachial a. superficialis m.
Biceps brachii tendon Flexor carpi ulnaris m.
Supinator m. (humeral head)
Ulnar n.
Radius Flexor carpi ulnaris m.
(ulnar head)
Anconeus Flexor digitorum
profundus m.
Ulna

Fig. 15.32 Axial T1 MRI, right elbow (superior to inferior).

299

Section 3: Upper and Lower Limb
A

B

Fig. 15.33 Transverse ultrasound cubital tunnel, proximal (A) and distal (B). The roof of the cubital tunnel is formed by the cubital tunnel retinaculum (white
arrows), a thickening of fascia that continues distally as the arcuate ligament/ligament of Osborne (black arrows), an aponeurotic sheet connecting the humeral
head (HH) and ulnar head (UH) of the flexor carpi ulnaris muscle. The floor of the cubital tunnel is formed by the groove between the olecranon process of the ulna
(O) and the medial epicondyle of the humerus (ME).

Ossification in the forearm (Table 15.9 and Fig. 15.35) Anterior (flexor) fascial compartment of the forearm

Table 15.9 Ossification centres of the forearm • The muscles of the anterior compartment can be
divided into superficial, intermediate and deep layers.
Radial diaphysis Appear Fuse
Proximal radius 8 weeks gestation • Blood supply: radial and ulnar arteries.
Distal radius 4–6 yrs 13–16 yrs • Nerve supply: median nerve except for the flexor
Ulnar diaphysis 1 yr 16–18 yrs
Proximal ulna 8 weeks gestation carpi ulnaris and the medial part of the flexor
Distal ulna 8–10 yrs 13–15 yrs digitorum profundus which are supplied by the ulnar
5–7 yrs 16–18 yrs nerve.
• All four muscles in the superficial layer have a common
Cross-sectional anatomy origin from the medial epicondyle of the humerus, the
common flexor origin (Tables 15.10–15.12 and Fig.
• Similarly to the arm, the forearm is encircled by a sheath of 15.37).
deep fascia, attached to the posterior subcutaneous border
of the ulna. Posterior (extensor) fascial compartment of the forearm

• A lateral intermuscular septum passes from the deep fascia • The muscles of the posterior compartment can be
to the radius. divided into superficial and deep layers.

• The interosseous membrane passes between the • Blood supply: anterior and posterior interosseous
interosseous borders of the radius and ulna, its fibres arteries, branches of the common interosseous branch of
orientated in an oblique downward and medial fashion: the ulnar artery.

· it is taut with the forearm in the mid-prone position • Nerve supply: radial nerve.
· it has a round opening in its distal third that allows • All of the muscles in the superficial layer have a

the passage of blood vessels. common origin from the lateral epicondyle and lateral
supracondylar ridge of the humerus, the common
• Together, the deep fascia, lateral intermuscular septum extensor origin (Tables 15.13, 15.14).
and interosseous membrane divide the forearm into
separate anterior and posterior fascial compartments Wrist
(Fig. 15.36). Plain radiographic anatomy

Radiocarpal joint
This is a synovial ellipsoid joint with articulation between the
distal radius and the scaphoid, lunate and triquetral carpal
bones.

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Chapter 15: The upper limb
A

B Radial n.
Ulnar n.
Biceps brachii Musculocutaneous
Brachialis n.

Pronator teres Median n.
Brachial a.
Bicipital Tendon biceps
aponeurosis brachii
Brachioradialis
Radial a.
Ulnar a.

Cubital fossa

Fig. 15.34 Coronal T1 MR of right elbow with associated schematic diagram demonstrating the cubital fossa. The cubital fossa is a triangular-shaped potential
space. Its base is marked by an imaginary line connecting the humeral epicondyles. Its apex is the point at which the medial borders of the brachioradialis (BR) and
pronator teres (PT) muscles cross.

Important radiographic anatomical features at the wrist • Variance refers to the articular surfaces of the radius
There are important anatomical measurements to evaluate on and ulna at the level of radiolunate articulation and is
posteroanterior and lateral radiographs of the wrist that help classified into:
orthopaedic surgeons plan surgery following trauma.
· neutral ulnar variance: the articular surfaces are at
Ulnar variance (Fig. 15.38) the same level

• This refers to anatomical variations in the lengths of the · positive ulnar variance: the ulna is distal to the radius
radius and ulna. · negative ulnar variance: the ulna is proximal to the

• On a posteroanterior radiograph of the distal forearm, the radius.
radial styloid process usually extends 9–12 mm distal to the
articular surface of the ulna. • False positives or negatives can occur as the wrist position
changes and these terms only hold true on a radiograph

301

Section 3: Upper and Lower Limb

A B

Styloid process ulna Diaphysis radius
Ulnar notch radius Diaphysis ulna
Tuberosity radius
Styloid process radius Neck radius
Diaphysis ulna Head radius
Olecranon ulna
Diaphysis radius
Tuberosity radius

Neck radius
Head radius
Olecranon ulna

Fig. 15.35 (A) AP radiograph, forearm; (B) lateral radiograph, forearm.

A

B Radius

Ulna

Anterior (flexor)
compartment

Posterior (extensor)
compartment

Intermuscular
septum

Interosseous
membrane

Deep fascia

Skin

Fig. 15.36 Axial T1 MR of right forearm with schematic diagram showing the compartments of the forearm. The interosseous membrane (IM) connects the radius
(R) and ulna (U). The intermuscular septum (white arrows) connects the deep fascia to the radius. These structures divide the forearm into an anterior (flexor)
compartment (AC) and posterior (extensor) compartment (PC).

performed with the wrist flat, the forearm in neutral Carpus and intercarpal joints (Fig. 15.42)
rotation and flexed to 90° and the shoulder abducted to 90°.
• The carpus is a set of eight bones formed into two rows
Ulnar slant of the radius (Fig. 15.39) (proximal and distal) each with four bones. From lateral to
• Angle produced by the articular surface of the distal medial:

radius on a posteroanterior radiograph. · proximal row: scaphoid, lunate, triquetral, and
• Normally 15–25°. pisiform

Palmar inclination (Fig. 15.40) · distal row: trapezium, trapezoid, capitate, and
• Angle of volar tilt of the articulating surface of the distal hamate.

radius on a lateral radiograph. • There is mixed opinion as to whether the pisiform is a true
• Usually 15–20° (Fig. 15.41). carpal bone or a sesamoid bone (see Hand section), as it
lies in an anterior plane to the other carpal bones and is
contained within the flexor carpi ulnaris tendon.

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Chapter 15: The upper limb

Table 15.10 Muscles of the superficial layer of the anterior compartment Table 15.11 Muscles of the intermediate layer of the anterior
of the forearm compartment of the forearm

Muscle Origin Insertion Action Muscle Origin Insertion Action
Pronator teres Pronation and
Humeral Lateral diaphysis flexion of forearm Flexor Humeroulnar By four Flexes proximal
Flexor carpi head: medial of radius digitorum head: medial tendons to the interphalangeal
radialis epicondyle of Flexes and superficialis epicondyle volar aspect joints of fingers;
Palmaris humerus abducts wrist of humerus; of the middle assists in flexing
longus Flexes wrist coronoid phalanges metacarpophalangeal
Ulnar head: process of ulna of the index, joints and wrist joint
Flexor carpi coronoid process Flexes and Radial head: middle, ring
ulnaris of ulna adducts wrist oblique line and little
of diaphysis of fingers
Medial Bases of index radius
epicondyle of and middle
humerus metacarpals

Medial Flexor Table 15.12 Muscles of the deep layer of the anterior compartment of the
epicondyle of retinaculum forearm
humerus and palmar
aponeurosis
Muscle Origin Insertion Action

Humeral Pisiform; hook of Flexor pollicis Anterior Distal phalanx of Flexes
head: medial hamate; base of thumb interphalangeal
epicondyle of little metacarpal longus diaphysis of joint of thumb
humerus By four tendons
radius to the volar Flexes distal
Ulnar head: aspect of the (and assists
olecranon Flexor Anteromedial distal phalanges with proximal)
process and digitorum diaphysis of of the index, interphalangeal
posterior border profundus ulna middle, ring and joints of fingers;
of ulna little fingers assists in flexing
wrist joint
Pronator Distal anterior Distal anterior
quadratus diaphysis of diaphysis of Pronates forearm
ulna radius

Table 15.13 Muscles of the superficial layer of the posterior compartment Table 15.14 Muscles of the deep layer of the posterior compartment of
of the forearm the forearm

Muscle Origin Insertion Action Muscle Origin Insertion Action

Brachioradialis Lateral Styloid process of Flexes elbow; Supinator Lateral Neck and Supinates forearm
supracondylar
ridge of humerus radius rotates arm epicondyle diaphysis of

to mid-prone of humerus; radius

position anular ligament;

Extensor carpi Lateral Dorsal surface Extends and supinator ridge
abducts wrist
radialis longus supracondylar of base of index of ulna

ridge of humerus metacarpal Abductor Posterior Base of thumb Abducts and extends

Extensor carpi Lateral Dorsal surface of Extends and pollicis longus diaphysis of metacarpal thumb
radialis brevis epicondyle of base of middle abducts wrist
metacarpal radius and ulna
humerus
Extensor Posterior Base of thumb Extends

Extensor Lateral Middle and Extends index, pollicis brevis diaphysis of proximal metacarpophalangeal
digitorum epicondyle of distal phalanges middle, ring and
humerus of index, little fingers and radius phalanx joint of thumb
middle, ring and wrist
little fingers Extensor Posterior Base of distal Extends
phalanx of interphalangeal joint
pollicis longus diaphysis of thumb of thumb

ulna

Extensor digiti Lateral Extensor hood of Extends little Extensor indicis Posterior Extensor hood Extends
diaphysis of of index finger metacarpophalangeal
minimi epicondyle of little finger finger ulna
joint of index finger
humerus

Extensor carpi Lateral Base of little Extends and
metacarpal adducts wrist
ulnaris epicondyle of • The intercarpal width should be uniform and not
more than 2 mm in adults, except for the scapholunate
humerus distance, which should be less than 3 mm.

Anconeus Lateral Olecranon Extends elbow • On the lateral radiograph, the capitate, lunate and distal
epicondyle of radius articulate with each other and should be seen
humerus process of ulna lying one on top of the other in a straight line.

• There are multiple intercarpal articulations which share Carpal stability
a common synovial cavity strengthened by multiple
intercarpal ligaments. • The carpal ring theory has been described by Lichtman to
explain carpal stability:

303

Section 3: Upper and Lower Limb
A

UPPER
MID

LOWER

B

Palmaris longus m. Flexor carpi ulnaris
Pronator teres m. m.
Flexor Basilic v.
carpi radialis m.
Flexor digitorum
Cephalic v. superficialis m.

Radial a. Flexor digitorum
profundus m.
Radial n.
Median n.
Brachioradialis m. Ulna

Supinator m. Radius

Extensor carpi Anconeus m.
radialis longus m.
Extensor carpi
Extensor carpi ulnaris m.
radialis brevis m.
Extensor digitorum
m.

Palmaris longus m. C

Flexor digitorum Flexor carpi ulnaris m.
superficialis m.
Flexor carpi Ulnar a.
radialis m. Ulnar n.

Radial a. Flexor digitorum
profundus m.
Radial n. Anterior interosseous
a.
Brachioradialis m. Ulna

Radius Extensor pollicis
Extensor carpi radialis longus m.
Extensor carpi ulnaris
longus m. m.

Abductor pollicis Interosseous
longus m. membrane

Extensor carpi radialis
brevis m.

Extensor digitorum m.

MID

Fig. 15.37 (A) Scout localizer image of the right forearm. The levels that panels (B), (C) and (D) have been taken at are denoted here as UPPER, MID and LOWER.
(B–D) Axial T1 MRI images, right forearm (upper, mid and lower). (E) Diagram to show the superficial, intermediate and deep muscles as well as the blood vessels
and nerves within the anterior compartment of the forearm. (F) Diagram to show the superficial and deep muscles as well as the blood vessels and nerves within

the posterior compartment of the forearm.

304

D Chapter 15: The upper limb

Median n. Flexor digitorum
superficialis m.
Radial a. Flexor carpi ulnaris m.
Ulnar n.
Radial n. Flexor digitorum
profundus m.
Radius Anterior interosseous
Extensor carpi a.
radialis longus tendon Ulna
Abductor pollicis Extensor pollicis
longus m.
longus m. Extensor carpi ulnaris
m.
E Extensor digitorum m.

Fig. 15.37 (cont.) Biceps brachii
Brachialis

Extensor carpi radialis longus
Brachioradialis

Flexor digitorum profundus
Flexor pollicis longus

Flexor digitorum superficialis
Pronator teres

Flexor carpi radialis
Palmaris longus

Flexor carpi ulnaris

305

Section 3: Upper and Lower Limb Triceps brachii
F Anconeus

Extensor carpi radialis longus
Extensor carpi radialis brevis

Brachioradialis
Extensor carpi ulnaris
Extensor digiti minimi

Extensor digitorum
Extensor indicis

Extensor pollicis longus tendon
Extensor pollicis brevis
Abductor pollicis longus

Fig. 15.37 (cont.)

· the proximal carpal row acts as an intercalated Cross-sectional anatomy
segment between the distal radius and ulna and the
distal carpal row Wrist joint ligaments (Fig. 15.46)
• Divided into intrinsic (between the carpal bones) and
· the proximal carpal row moves as a unit stabilized
by interosseous ligaments, allowing controlled extrinsic (between distal radius and the carpal bones).
mobility of the carpus • Intrinsic ligaments:

· in the event of a carpal fracture or interosseous · scapholunate and lunatotriquetral ligaments are the
ligament rupture, uncontrolled mobility can occur most important
resulting in instability of the intercalated segment, of
which there are two main types: – scapholunate ligament (Fig. 15.47):
composed of three parts, volar (trapezoid
– dorsal intercalated segment instability (DISI) shaped), middle (triangular shaped) and
– volar intercalated segment instability (VISI) dorsal (band shaped)

· on the lateral wrist radiograph, stability of the – middle part commonly has perforations that are
intercalated segment can be assessed by measuring clinically insignificant.
the:
• Extrinsic ligaments:
– scapholunate angle: normally 30–60°
– capitolunate angle: normally 0–30° (Fig. 15.43). · consist of volar and dorsal ligaments connecting distal
radius to carpal bones.
Ossification at the wrist (Table 15.15 and Figs. 15.44, 15.45)
Triangular fibrocartilage complex (TFCC) (Figs. 15.48, 15.49)
Table 15.15 Ossification centres of the carpus • This complex consists of five structures on the ulnar side of

Capitate Appear Scaphoid Appear the wrist:
Hamate 1–3 months Trapezium 4–6 yrs
Triquetral 2–4 months Trapezoid 4–6 yrs · triangular fibrocartilage
Lunate 2–3 yrs Pisiform 4–6 yrs · radio-ulnar ligament (dorsal and volar components)
2–4 yrs 8–12 yrs · ulnar collateral ligament
· meniscus homologue
· extensor carpi ulnaris tendon sheath.

306

Chapter 15: The upper limb

• The complex stabilizes the distal radio-ulnar joint and ulnar Extensor compartments of the wrist
aspect of the wrist and can be damaged following trauma. • The anatomy of the extensor surface of the wrist is defined

Carpal tunnel (Figs. 15.50, 15.51) by the extensor retinaculum and Lister’s tubercle (a dorsal
protuberance) of the distal radius.
• Fibro-osseous tunnel that permits the passage of tendons • The extensor retinaculum is an oblique thickening of fascia
and neurovascular structures from the forearm to the that attaches to the distal radius on the radial side and
hand. the triquetrum and pisiform on the ulnar side. Its deep
attachments to the radius and ulna divide the extensor
• Floor: formed by the concavity of the carpal arch. aspect of the wrist into six compartments, each with a
• Roof: formed by the flexor retinaculum. This is a single synovial sheath containing one or more tendons
(Table 15.16 and Fig. 15.52).
thickening of fascia that attaches to the scaphoid and
trapezium bones on the radial side and to the pisiform Fig. 15.39 AP radiograph of the wrist demonstrating ulnar slant of the radius.
and hamate bones on the ulnar side, forming an A horizontal line is drawn perpendicular to the longitudinal axis of the radius at
enclosed tunnel. the articulation with the ulna. A second line is drawn joining the radial styloid
• Contents: process and the ulnar aspect of the articular surface of the radius. The ulnar
slant is the angle formed between these two lines, normally 15–25°.
· median nerve
· four flexor digitorum superficialis tendons
· four flexor digitorum profunda tendons
· flexor pollicis longus tendon.

• The flexor retinaculum splits laterally to enclose the flexor
carpi radialis tendon in its own compartment.

Guyon tunnel

• This is a fibro-osseous tunnel that permits the passage of
the ulnar nerve as well as the ulnar artery and vein.

• Its floor is formed by the flexor retinaculum and its roof by
the palmar carpal ligament.

• It has a proximal radial wall formed by the pisiform and a
slightly distal ulnar wall formed by the hook of hamate.

Fig. 15.38 AP radiograph of the wrist demonstrating neutral ulnar variance. Fig. 15.40 Lateral radiograph of the wrist demonstrating palmar inclination.
The radial styloid process lies 9–12 mm distal to the ulnar articular surface. A horizontal line is drawn at the level of the radial styloid, perpendicular to the
The radial and ulnar articular surfaces are at the same level. longitudinal axis of the radius. A second line is drawn joining the dorsal and
volar aspects of the radial articular surface. The palmar inclination is the angle
formed between these two lines, normally 15–20°.

307

Section 3: Upper and Lower Limb

A

Base of metacarpals Sesamoid bone

Hook of hamate Base of metacarpals
Hamate Trapezoid
Pisiform Trapezium
Scaphoid
Triquetral Styloid process radius
Lunate Capitate
Radius
Styloid process ulna
Ulna Pisiform

Ulnar (sigmoid)
notch of radius

B

Capitate
Lunate
Radius

Fig. 15.41 (A) AP radiograph, right wrist; (B) lateral radiograph, right wrist. Hand
Plain radiographic anatomy (Fig. 15.53)
First carpometacarpal
compartment Metacarpal bones
To prevent confusion, it is easiest to refer to the digits by name
Intermetacarpal (thumb and index, middle, ring and little fingers) rather than
compartment by number.

Common carpometacarpal There are five metacarpal bones, each related to a digit. They
compartment consist of a proximal base, a diaphysis, a neck and a distal head.

Midcarpal compartment Phalangeal bones
Radiocarpal joint
• The phalanges are the bones of the digits.
Pisiform-triquetral space • The thumb has two, the proximal and distal phalanges and

Fig. 15.42 Diagram to show the carpal joint compartments. the remaining digits have three, the proximal, middle and
distal phalanges.
308 • Each phalanx has a proximal base, a body and a distal head.

Sesamoid bones

• These are small bones found within tendons that pass over
osseous or articular surfaces.

• The majority of the sesamoid bone is contained within the
tendon and its free surface is lined with cartilage.

Table 15.16 Extensor compartments Chapter 15: The upper limb

Extensor Location Contents
compartment
1 Radial to the radial styloid Extensor pollicis brevis and abductor pollicis longus tendons
2 Ulnar to compartment 1; radial to Lister’s tubercle Extensor carpi radialis brevis and longus tendons
3 Ulnar to Lister’s tubercle Extensor pollicis longus tendon
4 Ulnar to compartment 3 Four extensor digitorum tendons; extensor indicis tendon
5 Ulnar to compartment 4; dorsal to the radio-ulnar interval Extensor digiti minimi tendon
6 Between head and styloid process of ulna Extensor carpi ulnaris tendon

AB

Fig. 15.43 (A) Lateral radiograph of the right wrist showing the normal scapholunate angle; (B) lateral radiograph of the right wrist showing the normal
capitolunate angle. The scapholunate angle is calculated by drawing lines through the longitudinal axes of the scaphoid and lunate – it should normally be
between 30 and 60°. The capitolunate angle is calculated by drawing lines through the longitudinal axes of the capitate and lunate – it should normally be
between 0 and 30°. C = capitate; DR = distal radius; L = lunate; MF = middle finger metacarpal; S = scaphoid.

Trapezoid Hook of hamate
Trapezium Hamate
Pisiform
Capitate Triquetral
Scaphoid Styloid process radius
Styloid process ulna Lunate
Ulna
Radius
309
Fig. 15.44 Surface-shaded reformat CT, right wrist.

Section 3: Upper and Lower Limb

Flexor digitorum A Ulnar n.
superficialis tendon B
Ulnar a.
Median n.
Radial a. Flexor retinaculum
Flexor digitorum
superficialis m. Flexor carpi ulnaris
Flexor pollicis tendon
longus tendon Flexor digitorum
Abductor pollicis profundus tendon
longus tendon
Extensor pollicis Ulna
brevis tendon Extensor carpi
ulnaris tendon
Radius Extensor digit minimi
Extensor carpi radialis tendon
Extensor
longus tendon digitorum tendon
Extensor carpi
radialis brevis tendon Flexor retinaculum
Lister’s (dorsal) Ulnar n.
tubercle radius Ulnar a.
Extensor pollicis
longus tendon Flexor digitorum
superficialis m.
Median n. Abductor digiti
minimi m.
Abductor pollicis Hook of hamate
brevis m. Flexor digitorum
profundus tendon
Flexor pollicis Base of little metacarpal
longus tendon
Extensor digiti
Trapezium minimi tendon
Hamate
Trapezoid Extensor digitorum
tendon
Extensor carpi radialis Capitate
longus tendon

Extensor pollicis
longus tendon

Extensor carpi radialis
brevis tendon

Fig. 15.45 Axial T1 MRI, right wrist (radio-ulnar joint and carpal tunnel levels).

• In the upper limb, there are up to five sesamoid bones, all Interphalangeal joints
contained within the hand or wrist: three are related to the
thumb (two at the metacarpophalangeal (MCP) joint and • These are synovial hinge joints that allow flexion and
one at the interphalangeal joint) and one each at the MCP extension.
joints of the index and little fingers.
Ossification in the hand (Table 15.17)
• There is mixed opinion as to whether the pisiform is a
carpal or a sesamoid bone, as it lies in an anterior plane Table 15.17 Ossification centres of the hand
to the rest of the carpal bones and is contained within the
flexor carpi ulnaris tendon. Metacarpal diaphysis Appear Fuse
Metacarpal head 9 weeks gestation 14–19 yrs
Carpometacarpal joints (Fig. 15.54) Phalangeal diaphysis 1–2 yrs 14–18 yrs
Phalangeal base 8–12 weeks gestation
• The carpal bones articulate with the metacarpal bones at 1–3 yrs
the five carpometacarpal joints.
Cross-sectional anatomy
• The thumb carpometacarpal joint is the most mobile
articulation as it is a synovial saddle joint between the Digital flexor sheath (Figs. 15.55, 15.56)
trapezium and the thumb metacarpal.
• Smooth movement of the flexor tendons of the hand is
Metacarpophalangeal joints maintained by the digital flexor sheath.

• These are synovial hinge joints between the heads of • This consists of an inner synovial (membranous) layer and
the metacarpals and the proximal phalanges of the an outer pulley (retinacular) layer.
digits.
• The inner membranous layer is a closed synovial
system that bathes the flexor tendons, provides

310

Volar ligaments of the wrist Chapter 15: The upper limb

Volar capitohamate ligament Volar capitotrapezoid
Lunotriquetral ligament ligament

Ulnocarpal meniscus homologue Deltoid ligament
Ulnolunate ligament Radial collateral ligament
Radioscaphocapitate
Dorsal ligaments of the wrist ligament
Radiolunate ligament
Trapeziotrapezoid ligament Radioscapholunate ligament
Dorsal intercarpal ligament
Dorsal capitotrapezoid ligament
Radioscaphoid ligament Dorsal capitohamate ligament

Radiotriquetral ligament
Radiolunate ligament

Fig. 15.46 Diagram to show the wrist joint ligaments.

Fig. 15.47 Axial fat-saturated T1 MRI arthrogram of the right wrist (post intra- nutrition and facilitates smooth movement of the
articular gadolinium injection) demonstrating the scapholunate ligament. tendons in flexion.
Image demonstrating the dorsal, mid and volar parts of the scapholunate • The outer retinacular layer consists of bands of fibrous
ligament. S = scaphoid; L = lunate; SLL = scapholunate ligament. tissue that enclose the tendon and synovial sheath and
help prevent buckling of these structures during flexion.
It consists of the five annular pulleys (A1–A5) and four
cruciform pulleys (C1–C4).

Flexor digitorum tendons (Figs. 15.57, 15.58)

• The flexor digitorum superficialis tendon lies superficial to
the profundus tendon in the palm.

• As it courses distally, it divides into two slips to pass laterally
and then deep to the profundus tendon and eventually
inserts onto the proximal aspect of the middle phalanx.

• The flexor digitorum profundus tendon inserts distally onto
the distal phalanx.

Dorsal extensor hood (Fig. 15.59)

• This is a fibrous expansion on the dorsum of the proximal
phalanx of each digit blending with the respective extensor
tendon.

311

Section 3: Upper and Lower Limb

Extensor carpi Triangular
ulnaris fibrocartilage

Ulnar collateral Radio-ulnar
ligament ligament

Fig. 15.49 Coronal fat-saturated T1-weighted MRI arthrogram, right
wrist (post intra-articular gadolinium injection). Image demonstrating the
components of the triangulo-fibrocartilaginous complex. ECU = extensor
carpi ulnaris tendon; MH = meniscus homologue; R = radius; RUL = radio-
ulnar ligament; TFC = triangulo-fibrocartilage; U = ulna.

Fig. 15.48 Diagram to show the components of the triangular fibrocartilage
complex (TFCC).

Palmaris longus tendon Ulnar VOLAR Flexor retinaculum
Flexor digitorum superficialis tendon a. DORSAL
Thenar
Flexor digitorum profundus tendon Ulnar muscle
Flexor carpi radialis tendon n.
Median RADIAL
Flexor pollicis longus tendon Pisiform n.
Abductor pollicis longus tendon
Extensor pollicis brevis tendon ULNAR Scaphoid
Extensor pollicis longus tendon
Extensor carpi radialis longus tendon Basilic Cephalic
Extensor carpi radialis brevis tendon v. v.

Extensor indicis tendon Radial
Extensor digitorum tendons a.
Extensor digiti minimi tendon
Extensor carpi ulnaris tendon

Fig. 15.50 Diagram to show the carpal and extensor tunnels and their contents.

312

Chapter 15: The upper limb

Fig. 15.51 Transverse ultrasound of the wrist showing the carpal and Guyon tunnels (proximal and distal). The roof of the carpal tunnel is formed by the flexor
retinaculum (white arrowheads) and the floor by the carpal bones. The roof of the Guyon tunnel is formed by the palmar carpal ligament. FDP = flexor digitorum
profundus tendons; FDS = flexor digitorum superficialis tendons; FPL = flexor pollicis longus tendon; H = hamate; M = median nerve; PCL = palmar carpal ligament;
P = pisiform; S = scaphoid; T = trapezium; U = ulnar nerve; UA = ulnar artery.

AB

D
C

E

Fig. 15.52 Transverse ultrasound images demonstrating the extensor compartments of
the wrist and their contents. Extensor compartment 1 (A) contains the extensor pollicis
brevis (EPB) and abductor pollicis longus (APL) tendons. They lie superficial to the radial
artery (RA) and veins (white arrowheads). The extensor pollicis tendon of compartment 3
passes superficially to compartment 1 from the ulnar to the radial side as it courses distally.
Extensor compartment 2 (B) contains the extensor carpi radialis brevis (ECRB) and longus
(ECRL) tendons. The compartment lies on the radial side of Lister’s tubercle of the radius (LT).
Extensor compartment 3 (C, D) contains the extensor pollicis longus (EPL) tendon. It lies on
the ulnar side of Lister’s tubercle of the radius (LT). Extensor compartment 4 (C, D) contains
the extensor digitorum (ED) and extensor indicis (EI) tendons. Extensor compartment 5 (D)
contains the extensor digiti minimi (EDM) tendon. It lies superficial to the distal radio-ulnar
joint (DRUJ). Extensor compartment 6 (E) contains the extensor carpi ulnaris (ECU) tendon.
DR = distal radius; DU = distal ulna; CV = cephalic vein; ER = extensor retinaculum.

313

Section 3: Upper and Lower Limb Distal phalanx

Head index finger Distal interphalangeal joint
middle phalanx
Diaphysis index Head ring finger proximal
phalanx
finger middle phalanx Diaphysis ring finger
Base index proximal phalanx
Base ring finger
finger middle phalanx proximal phalanx
Proximal Metacarpophalangeal joint

interphalangeal joint Metacarpal Proximal phalanx Middle Distal
phalanx phalanx
Interphalangeal
joint of thumb Flexor tendon sheath A1 C1
Palmar aponeurosis A2 C2
Sesamoid bone A3 C3
Head thumb metacarpal A4 C4
Diaphysis thumb metacarpal A5
Base thumb metacarpal
Fig. 15.55 Diagram to show the layers of the digital flexor sheath.
Fig. 15.53 AP radiograph, hand.

Distal
interphalangeal joint

Proximal
interphalangeal joint
Capsule of metacarpo-

phalangeal joint
Palmar ligaments

Deep transverse
metacarpal ligament

Fig. 15.54 Diagram to show the carpometacarpal, metacarpophalangeal and
interphalangeal joints.

Fig. 15.56 Longitudinal ultrasound of the digital flexor sheath. The abnormal,
thickened A1 pulley is normally < 1.5 mm thick and is easily visible on
ultrasound. FT = flexor tendon; MC = metacarpal; PP = proximal phalanx.

314

Chapter 15: The upper limb
AB

CD

Fig. 15.57 A–D (proximal to distal): Transverse ultrasound of the flexor digitorum tendons from the palm to the middle phalanx demonstrating the relationship
between the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) tendons. At the level of the palm (A) the flexor digitorum superficialis tendon
lies superficial to the flexor digitorum profundus tendon. At the level of the proximal third of the proximal phalanx (B) the FDS tendon divides into two slips which
pass to the radial and ulnar aspects of the FDP tendon as they course distally (C, white arrows). The FDS slips then reunite deep to the FDP tendon (D, white arrows)
and the FDS inserts onto the proximal aspect of the middle phalanx.

Fig. 15.58 Extended field of view longitudinal ultrasound showing the flexor • It is triangular in shape with its dorsal base wrapped around
digitorum profundus tendon. The flexor digitorum profundus tendon (white the extensor aspect of the metacarpophalangeal joint.
arrowheads) lies on the flexor surface of the phalanges and inserts onto the
distal phalanx. The volar plates are static stabilizers of the interphalangeal • It is attached to the interossei and lumbrical muscles,
joints. affording much more precise movement of the fingers, as
well as to the deep transverse metacarpal ligaments.

• Each expansion forms a mobile hood that moves distally
with flexion of the metacarpophalangeal joint.

Palmar aponeurosis (Fig. 15.60)

• This is a thickening of the deep fascia of the palm.
• It is attached to the skin distally and is triangular in shape,

with its apex attached to the flexor retinaculum or palmaris
longus tendon when present.
• It is composed of longitudinal fibres that extend towards
the digits and transverse fibres that interconnect the
longitudinal fibres.

Metacarpophalangeal joint of the thumb (Fig. 15.61)
• The metacarpophalangeal joint of the thumb is

stabilized by:

315

Section 3: Upper and Lower Limb into the tear and prevent healing, termed a Stener
lesion. This usually requires surgical repair.
· static restraints: ulnar collateral ligament; radial
collateral ligament; volar plate; dorsal joint capsule Intrinsic muscles of the hand

· dynamic restraints: intrinsic and extrinsic muscles of • The small muscles of the hand all originate in the hand
the thumb. and are involved with precision movement and grip.

• The ulnar collateral ligament (UCL) can be injured • They are all innervated by the ulnar nerve except
following a valgus strain to the thumb: for the three thenar muscles and the lateral two
· normally, the aponeurosis of the adductor pollicis lumbricals, which are innervated by the median nerve
muscle (AA) lies superficial to the UCL (Table 15.18 and Figs. 15.62, 15.63).
· in full thickness rupture of the UCL, the AA can dip

A
B

Fig. 15.59 Transverse and longitudinal ultrasounds of the digital extensor hood. The dorsal extensor hood (white arrowheads) lies on the extensor surface of
extensor digitorum tendon (ED), blending with it and attaching to the proximal phalanx (PP) on each side. DV = digital vein; MCPJ = metacarpophalangeal joint.

Tendon of
palmaris longus

Longitudinal fibres of Fig. 15.61 Longitudinal ultrasound of the ulnar surface of the thumb
palmar aponeurosis metacarpophalangeal joint. The ulnar collateral ligament (white arrowheads) is
a static restraint on the metacarpophalangeal joint to valgus strain. It attaches
Transverse fibres of to the distal metacarpal (MC) and proximal aspect of the proximal phalanx
palmar aponeurosis (PP). It normally lies deep to the adductor pollicis aponeurosis (AA).

Superficial tranverse
metacarpal ligament

Fig. 15.60 Diagram demonstrating the palmar aponeurosis.

316

Chapter 15: The upper limb

Table 15.18

Muscle Origin Insertion Action

Palmaris brevis Flexor retinaculum; palmar aponeurosis Skin of palm Improves grip

Lumbricals (four) Tendons of flexor digitorum profundus Extensor hoods of index, middle, Flexes metacarpophalangeal joints and
ring and little fingers extends interphalangeal joints of fingers

Palmar interossei (four) Sides of thumb, index, ring and little Extensor hoods and proximal phalanges Adduct fingers towards middle finger
metacarpals of thumb, index, ring and little fingers

Dorsal interossei (four) Sides of metacarpals Extensor hoods and proximal phalanges Abduct fingers away from middle finger
of index, middle and ring fingers

Adductor pollicis Oblique head: index and middle metacarpals Base of proximal phalanx of thumb Adduction of thumb
Transverse head: middle metacarpal

Thenar muscles

Abductor pollicis brevis Scaphoid; trapezium; flexor retinaculum Bases of proximal phalanx of thumb Abduction of thumb

Flexor pollicis brevis Flexor retinaculum Base of proximal phalanx of thumb Flexes metacarpophalangeal joint of thumb

Opponens pollicis Flexor retinaculum Diaphysis of metacarpal of thumb Medially rotates thumb

Hypothenar muscles

Abductor digiti minimi Pisiform Base of proximal phalanx of little finger Abducts little finger

Flexor digiti minimi Flexor retinaculum Base of proximal phalanx of little finger Flexes little finger

Opponens digiti minimi Flexor retinaculum Metacarpal of little finger Laterally rotates little finger

“Anatomical snuff box”

Radial a.
Ulnar a.

Ulnar n.
Pisiform
Median n.

Deep palmar arch
Superficial palmar
arch

Radial a. Radial n.

Cutaneous innervation Palmar Dorsal

Superficial branch
of radial n.

Superficial branch
of median n.

Superficial branch
of ulnar n.

Fig. 15.62 Diagram to show the neurological and vascular supply of the hand.

317

:

Flexor pollicis A Flexor pollicis longus
brevis m. tendon
Ulnar a.
Abductor pollicis Flexor digiti minimi
brevis m. tendon
Flexor digitorum
Opponens pollicis m. superficialis tendon
Abductor digiti minimi
Metacarpal thumb m.
Adductor pollicis m. Opponens digiti minimi
m.
Flexor digitorum Metacarpal little finger
profundus tendon Extensor digiti minimi
Metacarpal index finger tendon
Metacarpal ring finger
Metacarpal Palmar interosseous
middle finger m.

Extensor digitorum Abductor digiti
tendon minimi m.
Flexor digiti
B minimi tendon
Flexor digitorum
Flexor digitorum profundus tendon
superficialis tendon Palmar interosseous m.

Flexor pollicis Extensor digitorum
brevis m. tendon
Dorsal interossei m.
Abductor pollicis
brevis m. Flexor digitorum
profundus tendon
Adductor pollicis m. Extensor digitorum tendon

C

Flexor digitorum
superficialis tendon
Flexor pollicis longus

tendon

Fig. 15.63 Axial T1 MRI, right hand (proximal, mid and distal).

318

Section 3 Upper and Lower Limb

Chapter The lower limb

16 Gonzalo Ansede, Adam W. M. Mitchell and Jeremiah C. Healy

Imaging modalities The pelvis
Plain radiography Bone anatomy

Plain radiography demonstrates osseous anatomy and provides Adult pelvis
some detail of the soft tissue anatomy. The pelvic bone is composed of three parts; the ilium, ischium
and pubis. These meet at the triradiate cartilage, seen as a
Cross-sectional imaging lucency within the acetabulum in the immature skeleton
(Figs. 16.1–16.3).
CT
Multi-slice CT allows high-resolution 3D reconstructions of The sacrum
the lower limb that enable exceptional visualization of the bony
anatomy. Soft tissues including muscles, tendons and joints can • Triangular bone formed by five fused vertebrae.
also be identified but these are optimally assessed with sonog- • Four pairs of dorsal and ventral foramina for the respective
raphy and MR imaging.
rami of the sacral nerves.
Sonography • The base of the sacral body is located superiorly and
Sonography allows high spatial resolution and dynamic imag-
ing of the soft tissues not obscured by osseous structures. It is articulates with the lumbar spine.
particularly optimal for visualization of small and superficial • The sacral ala, on either side of the body of the base of the
structures (ligaments, tendons) as well as muscle compart-
ments and the neonatal/infant hip. sacrum, are large triangular surfaces, which support the
psoas major and the lumbosacral trunk.
MRI • The ear-shaped (auricular) surface articulates with the
MR imaging offers high contrast resolution imaging of the ilium and occupies the wide superior aspect of the lateral
musculoskeletal anatomy. Intra-articular structures are opti- sacral surface.
mally assessed on MR arthrography. • The sacral hiatus is a horseshoe-shaped deficiency in the
lower end of the dorsal surface communicating with the
sacral canal.

Sacroiliac joints Sacral spine
Anterior inferior
Sacral foramina
iliac spine Coccyx
Anterior acetabulum
Iliopectineal line Posterior acetabulum
Ischial inferior ramus Pubic body
Ischial tuberosity
Greater trochanter
Intertrochanteric crest

Lesser trochanter

Fig. 16.1 Pelvis frontal radiograph.

Applied Radiological Anatomy, 2nd Edition ed. Paul Butler, Adam W.M. Mitchell and Jeremiah C. Healy. Published by Cambridge University Press.
© Cambridge University Press 2011.

319

Section 3: Upper and Lower Limb

Cotyloid fossa Posterior aspect
Pubic body neck of femur

Anterior aspect
neck of femur
Greater trochanter

Lesser trochanter

Fig. 16.2 Hip lateral radiograph.

A Superior

Articular surface Medial Iliac crest
for sacrum
Iliac tubercle
Iliopectineal line
Anterior superior
Superior iliac spine
pubic ramus Iliac fossa
Anterior inferior
Pubic crest iliac spine
Pubic tubercle
Anterior acetabulum
Pubic body
Posterior acetabulum

Obturator foramen
Inferior pubic ramus

Fig. 16.3 Surface-shaded CT image of the pelvic bone. Anterior (A), lateral (B) and medial (C) views.

320

B Chapter 16: The lower limb

Iliac crest Anterior Posterior superior
iliac spine
Iliac tubercle
Posterior inferior
Anterior superior iliac spine
iliac spine Greater sciatic
notch
Posterior inferior Posterior acetabulum
iliac spine Ischial spine
Lesser sciatic notch
Cotyloid fossa
Anterior acetabulum Ischial tuberosity

Obturator foramen
Inferior pubic ramus

Inferior

C Iliac crest
Iliac fossa
Articular surface
for sacrum

Greater sciatic notch Posterior Iliopectineal line
Pubic body
Ischial spine Pubic tubercle
Lesser sciatic notch Obturator foramen

Ischial tuberosity

Inferior

Fig. 16.3 (cont.)

The coccyx, a triangular bone formed by three to five fused Infant pelvis
vertebrae, articulates with the inferior end of the sacrum The femoral capital epiphyses can be evaluated:
• on sonography from birth until ossification (at 3 to
The sacrum and pelvic bones form a bone ring with an
intervening pubic symphysis and a pair of sacroiliac joints. Like 6 months)
a Polo mint, the ring cannot be broken in a single location. Two • on plain radiography afterwards (Fig. 16.5).
or more sites of the ring must be disturbed when the ring is
broken (Fig. 16.4).

321

Section 3: Upper and Lower Limb Superior
A sacral notch
Sacral body
Sacral ala
Pelvic surface
Lateral mass
Anterior sacral Inferolateral
angle
foramina Transverse
process
Sacrococcygeal of coccyx
joint Coccygeal
apex
B
Superior
Superior sacral notch
articular facet
Median crest
Intermediate
crest Sacral hiatus

Lateral crest Transverse
process
Posterior of coccyx
sacral Coccygeal
apex
foramina

Cornu of sacrum

Fig. 16.4 Surface-shaded CT images of the sacrum. Anterior (A), posterior (B) and lateral (C) views.

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C Chapter 16: The lower limb

Median crest Superior articular
process
Lateral crest Sacral body
Auricular surface
Anterior
Sacrococcygeal
Cornu of joint
sacrum Coccygeal apex

Fig. 16.4 (cont.) Inferior

Ischium

Triradiate cartilage
Superior femoral epiphysis

Epiphyseal plate Pubis
Pubic symphysis
Ossifying greater trochanter
Ischium

Ischio-pubic cartilage

Fig. 16.5 Immature pelvis frontal radiograph.

Ossification of the pelvis and sacrum • The iliopectineal line (junction between the ilium and
pubis) is a smooth curved line extending superiorly from
• Epiphyses are secondary ossification centres at the end of the superior border of the superior pubic ramus.
a long bone normally forming part of a joint (Tables 16.1,
16.2). • The ilioischial line (junction between the ilium and
ischium) is a smooth curve extending superiorly from the
• Apophyses are secondary ossification centres that do not superior border of the inferior pubic ramus.
articulate but may have tendinous insertions
• The acetabular tear drop is formed by the quadrilateral
• Secondary ossification centres may appear irregular and plate of the ilium medially, the inferior part of the
fragmented in the normal immature skeleton. acetabular fossa inferiorly and the anterior part of the
acetabular fossa laterally. The distance from the acetabular
Pelvis radiographic assessment (Figs. 16.6 and 16.7) teardrop to the medial aspect of the femoral head should be
less than 11 mm and symmetrical (±2 mm).
• Shenton’s line is an arc formed by the superior border of
the obturator foramen and the medial aspect of the femoral
neck and should be smooth.

323

Section 3: Upper and Lower Limb

Table 16.1 Ossification of the pelvis Assessment of the infant hip for developmental dysplasia of
the hip and dislocation can be made with the following:
Ossification centre Appear Fuse • Shenton’s line.
Ilium 8 weeks gestation 7–8 yrs • The Y line runs along the triradiate cartilages at the
Ischium 18–22 weeks gestation
Pubis 18–22 weeks gestation 20–25 yrs unossified acetabular centres between the three pelvis
Triradiate ligament: two Puberty 20–25 yrs bones.
ossification centres. 16–20 yrs • Perkin’s line is drawn perpendicular to the Y line along
Iliac crest Puberty the superior corner of the bony acetabulum. The superior
Capital femoral epiphysis 3–6 months capital epiphysis should lie in the inner lower quadrant.
• The acetabular angle (15–35°) between the Y line and a line
Table 16.2 Ossification of the sacrum is analogous to the remainder of drawn across the roof of the acetabulum.
the spine • The iliac angle (44–74°) between the Y line and a line drawn
along the anterior aspect of the ilium.
Ossification centre Appear Fuse • Lines along the femoral shafts meet at the midline in Von
Vertebral body centre 10–20 weeks gestation Rosen’s view (legs abducted 45° and internally rotated)
Half of vertebral arch 10–20 weeks gestation Vertebra and both (Fig. 16.8).
vertebral arches
Vestigial costal elements 6–8 months gestation fuse at 8 years Joints

Ipsilateral vertebral Hip joint
arch and costal Different imaging modalities allow evaluation of the hip joint
elements fuse at structures. Intrarticular features are best assessed on MR
5 years arthrography
• MR direct arthrography consists of percutaneous
• The outer margin of the anterior acetabular column is a
smooth line from the inferior margin of the superior pubic administration of a gadolinium solution into a joint,
ramus to the upper outer margin of the acetabular roof. causing distension of the capsule (Fig. 16.10).
• In MR indirect arthrography, intravenous gadolinium
• The outer margin of the posterior acetabular column is a progressively accumulates in the joint synovium with a
smooth line from the inferior margin of the inferior pubic similar athrographic effect although no joint distension
ramus to the upper outer margin of the acetabular roof. The is achieved. Imaging is performed after an appropriate
posterior column extends more laterally than the anterior delay and lower limb exercises to allow maximal synovial
column. enhancement.

The hip

• The hip is a synovial ball and socket joint between the
femoral head and acetabulum and is best assessed with a
dedicated surface coil and on direct MR arthrography.

Perkins line Acetabular angle
Iliac angle Y line

Fig. 16.6 Pelvis assessment.

324

Anterior Chapter 16: The lower limb
acetabular margin
Acetabular
Iliopectineal tear drop
line Shenton’s
line
Posterior
acetabular margin

Ilioischial
line

Fig. 16.7 Lines in pelvis.

Fig. 16.8 Von Rosen’s view (legs abducted 45° and internally rotated) is used in the evaluation of developmental hip dysplasia. Lines along the femoral shafts
should meet at the midline in the normal pelvis.

A Hip joint capsule

Acetabular Greater trochanter
labrum Femoral head
Ilium
Acetabular roof

Triradiate
cartilage

Fig. 16.9 Neonatal hip sonography. The alpha angle is formed by the acetabular roof and the ilium. The beta angle is formed by the straight lateral edge of the
ilium and the end of the acetabular labrum. A mature hip should have an α angle > 60° and β angle < 55°.

325

Section 3: Upper and Lower Limb
B

Beta angle
Alpha angle

Fig. 16.9 (cont.) • The capsule is strongest superiorly and anteriorly and
attaches to the rim of the acetabulum and transverse
• The articular surface of the acetabulum is an inverted acetabular ligament. Distally it attaches to the trochanteric
horseshoe with a fat-filled central part (cotyloid fossa) line anteriorly and 1 cm proximal to the intertrochanteric
and an inferiorly placed acetabular notch bridged by the crest posteriorly and is reinforced by three strong
transverse acetabular ligament. The articular cartilage is ligaments:
thickest at the weight-bearing superior surface.
· the iliofemoral ligament is very strong, Y-shaped
• The ligamentum teres attaches to the cartilage deficient and runs from the intertrochanteric line (base of the
fovea capitis and the cotyloid fossa. Y) to the anterior inferior iliac spine (apex of the Y)

• The acetabular fibrocartilaginous labrum deepens · the triangular pubofemoral ligament inferiorly attaches
the articular cup and is seen, preferably on MR to the iliopubic eminence and superior pubic ramus
arthrography, as a triangular filling defect attached to the and blends distally with the capsule and iliofemoral
acetabular rim. The labrum is thickest posterosuperiorly ligament
and is deficient inferiorly where it is continuous with
the tranverse acetabular ligament. The joint capsule · the ischiofemoral ligament posteriorly has broad iliac
originates from the bone surrounding the external attachments and inserts into the inner aspect of the
aspect of the labrum, forming a well-defined recess, the greater trochanter.
perilabral recess.

A

Perilabral Labrum
recess Articular cartilage

Iliofemoral Capsule
ligament

Zona
orbicularis

Fig. 16.10 Hip joint MR arthrogram, axial (A) and coronal (B) images.

326

B Chapter 16: The lower limb

Labrum Cotyloid
Capsule fossa
Ligamentum
Zona teres
orbicularis Transverse
ligament

Fig. 16.10 (cont.) • The sacroiliac joints are synovial joints between the
flat and irregular surfaces of the sacrum and the ilium.
• The synovium covers the internal surface of the capsule, The hyaline cartilage on the anterior part of the sacral
intracapsular femoral neck, labrum, cotyloid fossa and and iliac articular surfaces is thinner than that on the
ligamentum teres. It may communicate with the psoas posterior part of the sacrum. Fibrous adhesions and
bursa anteriorly through a capsular defect. gradual fusion across the joint occurs with age, and this
may even lead to ossification in old age.
Sacroiliac joints (Fig. 16.11)
• The sacroiliac joints are symmetrical and as they lie in a Stability is conferred by the curvatures and irregularities of
the articular surfaces and by a number of ligaments.
coronal oblique plane, a dedicated coronal oblique view
is required.

A

Sacral ala Sacral body
Ilium SIJ

Gluteus maximus Rectum
Coccyx
Fig. 16.11 Sacroiliac joints, axial oblique MR images.

327

Section 3: Upper and Lower Limb Neural foramina
B
Sacral body
Sacral ala SIJ
Ilium

Gluteus maximus

Fig. 16.11 (cont.)

• The dense sacroiliac interosseous ligament, the Pubic symphysis
strongest ligament in the body, lies above and
posterior to the joint. • The pubic symphysis is a cartilaginous joint covered by
dense ligaments, and contains a fibrocartilaginous disc
• The sacrotuberous ligament runs from the ischial resembling an intervertebral disc (Figs. 16.12, 16.13).
tuberosity to the side of the sacrum and coccyx, and Stability is mainly provided by the interpubic disc and the
defines the posterior limit of the lesser sciatic foramen. superior and arcuate ligaments.

• The triangular sacrospinous ligament runs from the ischial • The superior ligament connects the pubic bones above, and
spine (apex) to the side of the sacrum and coccyx (base), reaches the pubic tubercle. The arcuate pubic ligament is
and separates the greater and lesser sciatic foramina. a thick arch of fibres connecting the inferior aspect of the
pubic bones. It blends with the interpubic disc and extends
• The iliolumbar ligament runs from the transverse process onto the inferior pubic ramus.
of the fifth lumbar vertebra to the iliac crest.
• The anterior pubic ligament strengthens the
These ligaments may calcify in old age and allow subtle interpubic disc, and is formed by interlacing collagen
rotatory movements at the sacroiliac joint particularly during fibres which decussate with the external oblique
pregnancy.

AB Linea alba
Anterior pubic
Rectus ligament
abdominis
Uterus Symphyseal
Insertion of disc
rectus
abdominis
Anterior pubic
ligament

Pubic body
Adductor
tendon and
arcuate
ligament
Adductor
longus m.

Fig. 16.12 Sagittal paramedian (a) and midline (b) MR images of the pubic symphysis.

328

A Chapter 16: The lower limb

Rectus abdominis Ilipsoas m.
and tendon
Gluteus minimus Body of ilium
Gluteus medius
Piriformis
Gluteus maximus Sacrum-coccyx

Ilipsoas m. and tendon B Rectus abdominis
Acetabular labrum
Sartorius Hip joint capsule
Tensor Anterior acetabular column
Posterior acetabular
fascia lata column

Femoral head Pectineus
Cotyloid fossa Femoral vessels
Greater trochanter Pubic body
Obturator internus Lesser trochanter
Ischium body
Gluteus maximus Sciatic n.

C

Sartorius
Rectus femoris
Tensor fascia lata

Ilipsoas m.

Obturator externus

Obturator internus

Gluteus maximus

D

Sartorius Adductor longus
Rectus femoris
Quadratus femoris
Tensor fascia lata
Vastus lateralis Semimembranosus
Adductor brevis tendon
Sciatic n.
Quadratus femoris Biceps femoris
Inferior pubic ramus conjoint tendon
Semitendinosus
Gluteus maximus

Fig. 16.13 Pelvis MR axial images. From superior to inferior.

329

Section 3: Upper and Lower Limb

aponeurosis and the medial tendons of the rectus • The superior and inferior gemelli merge with obturator
abdominis. internus tendon and lie superior and inferior to it.

• The proximal insertion of gracilis, adductor longus • Obturator internus and the gemelli fill the gap between
and adductor brevis on the anterior surface of the piriformis superiorly and quadratus femoris inferiorly.
pubic body is adjacent to the anterior pubic
ligament. • Obturator externus passes inferior to the hip joint
and is anterior to the sheet of muscle formed by the
Muscles of the pelvic girdle remaining lateral rotators.

Glutei Nerves and vessels

• All glutei muscles (Table 16.3) are hip extensors and Sciatic nerve
abductors and arise from the posterior surfaces of the The sciatic nerve (L4, 5, S1, 2, 3) exits the pelvis through the
ilium, sacrum and adjacent deep fascia. greater sciatic notch below piriformis to lie on the other hip
external rotators and is covered by gluteus maximus (Fig. 16.17).
• Gluteus maximus is the largest muscle in the body and is
the only muscle covering the greater trochanter, separated Greater sciatic foramen
by an intervening bursa.
• The greater sciatic foramen is bounded anterolaterally
• Medius and minimus attach to the greater trochanter by the greater sciatic notch of the ilium, posteromedially
and stabilize the hip when the contralateral limb is raised by the sacrotuberous ligament and inferiorly by the
during walking. sacrospinous ligament and the ischial spine.

Hip lateral rotators (Table 16.4 and Figs. 16.14–16.16) • Piriformis muscle passes through it to exit the pelvis
and divides into the supra- and infra-piriform foramina
• Piriformis passes posterior to the hip joint and through the transmitting the gluteal nerves and vessels, pudendal
greater sciatic foramen. nerves and vessels and the sciatic nerve among other
structures (Table 16.5).
• The sciatic nerve passes inferior to piriformis to become a
posterior relation of the other hip lateral rotators. Lesser sciatic foramen
The lesser sciatic foramen, bounded by the ischial spine, sacro-
• Quadratus femoris inserts into the quadrate tubercle, tuberous and sacrospinous ligaments, communicates the pelvis
unlike all other lateral hip rotators which insert into the with the posterior compartment of the thigh and transmits the
greater trochanter. obturator internus tendon, and the pudendal nerve and vessels
(Fig. 16.18).
• Obturator internus hooks around the lesser sciatic foramen
to attach to the greater trochanter. Obturator canal
The obturator canal is a passageway through the obturator
Table 16.3 Gluteal muscles foramen, formed by a defect of the obturator membrane, allow-
ing passage of the obturator artery, vein and nerve from the
Muscle Origin Insertion Action pelvis to the adductor compartment of the thigh.
Gluteus
maximus Lateral sacrum Gluteal tuberosity Keeps knee
extended; hip
Gluteus and posterior (femur) and iliotibial external rotator
medius
Gluteus iliac crest band Hip abductor and
minimus medial rotator
Outer surface Greater trochanter:
Hip abductor and
of ilium posterolateral surface medial rotator

Outer surface Greater trochanter:

of ilium anterior surface

Table 16.4 Lateral rotator muscles of the hip

Muscle Origin Insertion Action
Piriformis Anterior aspect of sacrum Hip lateral rotator and stabilizer
Anterior part of medial surface
Quadratus femoris Ischial tuberosity of greater trochanter Hip lateral rotator and stabilizer

Obturator externus Outer obturator membrane and Quadrate tubercle on posterior Hip lateral rotator
surrounding ischium/pubis aspect of femur
Obturator internus Hip lateral rotator
Inner obturator membrane and Trochanteric fossa on medial aspect
Gemellus superior surrounding ischium/pubis of greater trochanter Hip lateral rotator and stabilizer
Gemellus inferior Hip lateral rotator and stabilizer
Ischial spine Middle part of medial surface of
greater trochanter
Ischial tuberosity

330

A Chapter 16: The lower limb

Glutei Sciatic n.
Piriformis Obturator
internus
Quadratus
femoris Obturator internus
tendon
Hamstrings
tendon inserting Ischium-posterior
acetabular column
into ischial
tuberosity Piriformis tendon
Obturator internus
B tendon
Greater trochanter
Glutei Obturator membrane
Obturator
Quadratus Femoris
internus
Greater
trochanter
Quadratus
femoris

C

Glutei

Obturator
internus

Obturator
externus
Inferior pubic

ramus

Fig. 16.14 Hip external rotators MR coronal images. From posterior to anterior.

331

Section 3: Upper and Lower Limb Obturator internus tendon
D Lesser trochanter
Inferior pubic ramus
Glutei
Gluteus maximus
Obturator internus
Obturator externus Gluteus minimus
Quadratus femoris Piriformis
Gemellus superior
Adductors Obturator internus
Gemellus inferior
Fig. 16.14 (cont.)

Fig. 16.15 Hip rotators. Posterior view of the glutei and lateral rotators of the hip. The obturator externus (not shown) lies on a deeper anatomical plane.

Head The thigh
Bone anatomy
Fovea capitis
Femur
Obturator externus (I) The femur is the longest bone of the body and consists of a
head, neck, shaft and expanded lower end (Fig. 16.19).
Obturator interus
and gemelli (I) • The head is more than half a sphere and is directed
forwards, medially and upwards and has a central pit or
Piriformis (I) fovea where the ligamentum teres is attached.

Gluteus medius (I) • The blood supply to the head is derived from three sources:

Greater trochanter · the principal supply is from a vascular ring in close
association to the joint capsule
Lesser trochanter
· terminal medullary branches from the femoral shaft
Quadratus femoris (I) (I) = Insertion · negligible supply to the central part of the head from

Fig. 16.16 Insertion of lateral rotators into the greater trochanter. the artery of the ligamentum teres.

332

Chapter 16: The lower limb

Table 16.5 Foramina communicating the pelvis and the thigh Table 16.6 Anteversion of femoral neck

Foramen Vessels Nerves Other Age (years): 1 2 3–5 6–12 13–15 Up to 20
structures
Anteversion of < 50° < 30° 25° 20° 17° 11°
Obturator femoral head
Suprapiriform Superior Superior gluteal nerve internus
tendon
foramen gluteal

vessels Table 16.7 Ossification of the femur

Infrapiriform Inferior Sciatic nerve Ossification centre Appear Fuse
foramen gluteal Inferior gluteal nerve Femoral shaft (1y centre) 7th week gestation
vessels Pudendal nerve All fuse at
Internal Posterior femoral cutaneous Distal femoral epiphysis (2y centre) 9th month gestation 18–20 years
pudendal nerve Femoral head (2y centre) 3–6 months age
vessels Nerve to obturator internus Greater trochanter (2y centre) 4 years age
Lesser trochanter (2y centre) Puberty
Nerve to quadratus femoris

Lesser sciatic Internal Pudendal nerve

foramen pudendal Nerve to the obturator

vessels internus

Obturator Obturator Obturator nerve Muscles of the thigh
canal vessels
Anterior compartment
• The neck is about 5 cm long and makes an angle of 125–135°
with the shaft, and is also anteverted by 8°. The degree of • Hip flexors and knee extensors.
anteversion is larger in neonates and reduces progressively • Psoas major arises from the lumbar spine and twelfth
with age (Fig. 16.20 and Table 16.6).
vertebra, descends deep to the inguinal ligament and blends
• Between the greater and lesser trochanters, there is a rough with iliacus, which originates from the internal surface of
intertrochanteric line anteriorly and a more rounded the ilium, and inserts into the lesser trochanter. Psoas bursa
intertrochanteric crest posteriorly. separates psoas tendon from the anterior capsule of the hip
joint.
• The shaft of the femur is angled medially (10° in men, 14° in • Tensor fascia lata merges with the thickened lateral deep
women) so that the medial condyles at the knee are close to fascia of the thigh (fascia lata or iliotibial tract) which
each other but the heads are separated by the bony pelvis. inserts into the lateral tibial condyle.
• Sartorius is a strap muscle running from the AIIS (Anterior
• The distal shaft is angled posteriorly and expanded into inferior iliac spine) to the medial tibial condyle forming
medial and lateral condyles separated posteriorly by the part of the pes anserinus.
intercondylar fossa. • Quadriceps femoris inserts into the superior patellar border.
• Rectus femoris has a distinct intramuscular tendon and
• The medial condyle is larger and the inferior surface of the arises from the AIIS (straight head) and the superior
femur is nearly horizontal despite the shaft obliquity. margin of the acetabulum (reflected head) which may
appear irregular.
• The lateral condyle bears the majority of the patellar
articulation and is grooved posterolaterally by popliteus
tendon.

Sciatic notch Sacrospinous
ligament
Piriformis Sacrotuberous
Gemellus superior ligament
Obturator internus
Gemellus inferior Greater sciatic foramen
Lesser sciatic foramen
Sciatic n. Obturator canal

Fig. 16.17 Sciatic nerve exiting the pelvis. Fig. 16.18 Foramina communicating the pelvis to the lower limb.

333

Section 3: Upper and Lower Limb A

Femoral head Greater trochanter
Neck of femur Intertrochanteric line
Lesser trochanter

Medial

Adductor tubercle
Trochlea

B F
H

Greater trochanter Fovea capitis
Intertrochanteric crest Neck of femur

Gluteal tuberosity Lesser trochanter
Spiral line

Medial

Linea aspera

Lateral supracondylar ridge Medial supracondylar ridge
Popliteal surface
Intertrochanteric line
Adductor tubercle
Popliteal groove Intercondylar notch
Medial femoral condyle

Lateral femoral condyle F

Fig. 16.19 Surface-shaded CT images of the femur. Anterior (A), posterior (B) views.

334

Chapter 16: The lower limb

Table 16.8 Anterior thigh muscular compartment

Muscle Origin Insertion Action

Iliopsoas Inner surface ilium Lesser Hip
(iliacus) trochanter

Lumbar transverse
processes

Tensor Outer surface of Iliotibial band Maintains knee
extended and
fascia lata iliac crest abducts hip

Sartorius Ant sup iliac spine Upper medial Flexes and lat rotates
aspect prox hip; flexes and med
tibia rotates knee

Rectus Straight head: Quads Hip flexor; knee
femoris extensor
ant inf iliac spine tendon

Reflected head: ilium

above acetabulum

Femoral Vastus Extensive from Quads Knee extensor and
anteversion medialis medial aspect of
angle femur tendon and patella stabilizer

Fig. 16.20 Anteversion and angulation of the femoral neck. medial aspect

• Vastus intermedius, lateralis and medialis originate from of patella
the femur.
Vastus Extensive from Quads Knee extensor
• Vastus medialis has a lower musculotendinous junction lateralis lateral aspect of tendon
than its lateral counterpart and has horizontal fibres femur
inserting into the medial surface of the patella to stabilize
it and prevent (lateral) dislocation (Figs. 16.21, 16.22 and Vastus Anterior and lateral Quads Knee extensor
Table 16.8).
intermedius aspect of femur tendon
The adductor muscles
• The adductors insert along the linea aspera on the Table 16.9 Thigh adductors

posterior surface of the femur. Muscle Origin Insertion Action
• Gracilis, a thin strap muscle, acting as knee flexor and Adductor
magnus Ischial tuberosity Extensive along Adducts, extends
medial rotator of the flexed knee, forms part of the pes and med
anserinus. Adductor and ischiopubic gluteal line and rotates hip
• Adductor magnus is large with a broad attachment longus
including the adductor tubercle, and has an Adductor ramus adductor tubercle Adducts and med
adductor hiatus, a defect in its distal part allowing brevis rotates hip
passage of the femoral vessels into the popliteal Gracilis Pubic body Linea aspera
fossa (Figs. 16.21, 16.22 and table 16.9). (femur) Adducts hip
Pectineus
The hamstrings Pubic body and Linea aspera Adducts hip; flexes
• Hamstrings have a complex proximal insertion from the and med rotates
inf ramus (femur) knee
ischial tuberosity and flex the knee.
• Semimembranosus forms a membrane-like tendon Ischiopubic ramus Medial aspect of Flexes, adducts and
upper tibia med rotates hip
with complex distal tendinous expansions over the
posteromedial aspect of the tibial condyle, popliteus muscle Pectineal line Below lesser
and lateral femoral condyle, via the oblique popliteal trochanter
ligament.
• Semitendinosus is more posterior and passes over the Pes anserinus
medial collateral ligament to insert into the pes anserinus
aponeurosis. • Sartorius, gracilis and semitendinosus insert (from medial
• Biceps femoris crosses the hip and knee joint and is prone to lateral) into the anterolateral aspect of the medial tibial
to traumatic muscular tears. Biceps femoris has two condyle to form an aponeurosis.
proximal attachments, the long and short head; the latter
may be absent (Table 16.10 and Figs. 16.23, 16.24). • These muscles form a tripod: the apex is the pes anserinus
and the tripod base is a triangle formed by the muscles’
attachments on the pelvis (Fig. 16.25).

• Pes anserine bursa lies deep to the aponeurosis and may be
liable to injury from overuse.

Nerves and vessels

Sciatic nerve
The sciatic nerve travels in the hamstring compartment of the
thigh. It loses its gluteal cover proximally and is covered by
deep fascia until it dives deep to biceps femoris in the midline of
the hamstring compartment. It divides into the posterior tibial
and common peroneal nerves as it reaches the popliteal fossa.

335

Section 3: Upper and Lower Limb

Adductors Hip flexors
knee extensors
Fig. 16.21 Muscular compartments of the thigh.
Hamstrings
A
Rectus femoris
Sartorius Tensor fascia lata
Femoral a. Iliotibial band
Adductor longus Vastus lateralis
Femur
Gracilis Sciatic n.
Vastus medialis Gluteus maximus
Adductor brevis Semitendinosus
Adductor magnus

Biceps femoris
Semimembranosus

Fig. 16.22 Thigh axial MR images. From superior to inferior.

336

B Chapter 16: The lower limb

Rectus femoris Vastus intermedius
Vastus lateralis
Vastus medialis Femur
Sciatic n.
Sartorius Biceps femoris
Femoral a. Semitendinosus
Adductor longus Semimembranosus
Adductor magnus
Vastus intermedius
Gracilis Vastus lateralis
Sciatic n.
C Biceps femoris
Popliteal vessels
Vastus medialis
Semimembranosus 337

Sartorius
Gracilis

Semitendinosus

Fig. 16.22 (cont.)

Section 3: Upper and Lower Limb

Table 16.10 Hamstrings

Muscle Origin Insertion Action
Semimembranosus Ischial tuberosity (post surface) Complex over medial tibial condyle, Flexes and med rotates knee;
posterior knee capsule and oblique extends hip
Semitendinosus Ischial tuberosity (post surface) popliteal ligament
Biceps femoris Medial aspect of upper tibia Flexes and med rotates knee;
Long head: ischial tuberosity extends hip
Short head: linea aspera, lat femur Styloid process of fibular head, MCL Flexes and lat rotates knee; hip extensor
and lat tibial condyle (long head)

Obturator foramen Femoral nerve and vessels
The femoral nerve (L2, 3, 4), artery, vein and lymphatics (from
Greater sciatic notch lateral to medial) pass under the inguinal ligament to run
through the femoral triangle over the adductors. The femoral
Lesser sciatic notch nerve splits within the triangle and the vessels run distally to
pass through the adductor hiatus (adductor magnus) to enter
Obturator internus (I) the popliteal fossa (Fig. 16.26).

Adductor magnus (I) Knee
Plain radiography
Semitemdinosus and
biceps femoris (I) • The knee joint is formed by the femoral condyles, patella
and tibial plateau.
Semimembranosus (I)
• The joint space of the femoro-tibial compartments and the
Gemellus inferior (I) patello-femoral compartment should range between
3 and 8 mm.
Quadratus femoris (I)

Gemellus superior (I)

(I) = Insertion

Fig. 16.23 Hamstring origin. The long head of biceps and semitendinosus
have a common origin from a conjoint tendon. Semimembranosus is medial
to biceps femoris distally but its proximal attachment on the ischial tuberosity
lies superior and lateral to that of the conjoint tendon.

Gluteus maximus

A

Semimembranosus/
semitendinosus

Biceps femoris
Adductor magnus

Fig. 16.24 Thigh coronal MR images. From posterior to anterior.

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B Chapter 16: The lower limb

Femur Pectineus
Ischial tuberosity Adductor longus
Adductor magnus Rectus femoris

Vastus lateralis 339
Gracilis

Femoral vessels

C

Vastus lateralis
Vastus medialis

Fig. 16.24 (cont.)

Section 3: Upper and Lower Limb

Sartorius Gracilis • The suprapatellar bursa is best seen when distended with
Semitendinosus joint fluid and is normally less than 5 mm on a lateral view
Long head Semimembranosus (5–10 mm is borderline and > 10 mm is in keeping with a
biceps femoris joint effusion) (Figs. 16.27, 16.28).

Short head Patella and fabella
biceps femoris
• The patella is a flattened sesamoid bone within the
Fig. 16.25 Diagram of the pes anserine muscles (gracilis, semitendinosus and quadriceps tendon. It is triangular with an inferior apex
sartorius) forming an inverse tripod. lying about 1 cm proximal to the knee joint line in the erect
position.
Inguinal ligament
• The retropatellar articular surface is divided into a larger
Superficial lateral facet and a smaller medial facet for articulation with
epigastric vessels the corresponding femoral condyles. The anterior surface is
irregular owing to the entry of nutrient vessels.
Superficial iliac
circumflex vessels • Several ossification centres appear at 3 years and fuse at
Femoral n. puberty (Table 16.11). These may give rise to an irregular
appearance of the normal unfused patella. A bipartite
Sartorius (or multipartite) patella is a common variant when the
superolateral corner fails to fuse.
Superficial external
pudendal vessels • The fabella is a sesamoid bone frequently found in the
lateral head of gastrocnemius.
Deep external
pudendal vessels Knee joint

Gracilis The knee is a synovial hinge joint and the largest in the body
(Fig. 16.30).
Fig. 16.26 Femoral triangle.
Articular surfaces

• The medial and lateral tibiofemoral compartments,
between the corresponding femoral and tibial condyles,
have a joint space ranging from 3 to 8 mm.

• The medial tibial articular surface is larger than its lateral
rounder counterpart.

• The femoral condyles have a groove at the junction of the
patellar and tibial articular areas.

• The patellofemoral compartment is a saddle joint between
the femoral trochlea and patella, formed by a large steeper
lateral facet, resisting patellar lateral displacement, and two
smaller medial facets.

• The patellar articular cartilage varies in thickness.

Capsule

• The fibrous capsule attaches to the margin of the articular
surfaces.

• It is partly deficient superiorly, where the joint cavity
communicates with the suprapatellar bursa, and
posteriorly, where it may allow communication with the
semimembranosus and popliteal bursa.

• The capsule includes the tibial tuberosity and fibular head
and is pierced by popliteus tendon posteriorly.

• The capsule blends with and is strengthened by multiple
structures:

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