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(a)ii Lateral view
Radius


Humerus


Capitulum




Ulna



(b)i Anteroposterior view



Ulna

Distal radius

Humerus




joint, attaches to the margins of the radial notch of the lateral aspect
of the ulna. Like the radius, the shaft of the ulna gives origin to some
of the ¬‚exor and extensor muscle groups of the forearm. The distal
ulna gives rise to a medial styloid process and a small rounded head.
Capitulum
The radius and ulna are closely related by a strong interosseous
membrane, which divides the forearm into the anterior ¬‚exor and
Ulna
posterior extensor compartments. The ulna stabilizes the forearm and
Radial
allows the radius to rotate about its axis. The proximal and distal epiphysis
radioulnar joints are both synovial pivot joints. The capsule of the
Radius
proximal joint is continuous with the synovial capsule of the elbow
joint. The capsule of the distal radioulnar joint does not usually com-
municate with the capsule of the wrist joint. Because of the close rela-
tionship between the radius and ulna, disruption and angulation of
one bone are often accompanied by a fracture or dislocation of the
second. In trauma cases involving a fracture of one of the components
of the forearm, imaging of the remainder of the forearm should be
performed, to include the elbow and wrist, so that further injuries Fig. 12.11. Radiographs of the secondary ossi¬cation centers of the elbow.
are not missed. (a) 2 years, (b) 5 years, (c) 5 years, (d) 10“11 years, (e) 12 years.


119
alex m. barnacle and adam w. m. mitchell
The upper limb


(b)ii (c)i Anteroposterior view
Lateral view


Humerus

Humerus




Capitulum
Medial
epicondyle Capitulum
Ulna
Radial head

Radius Radial head


Ulna Radius

(c)ii Lateral view




Humerus
(d)i


Medial
epicondyle
Anteroposterior view
Capitulum


Ulna
Humerus
Radius Radial head



(d)ii Lateral view

Humerus


Capitulum
Radius and head

Trochlea
Radial
head


Ulna Radius
Capitulum

Olecranon



(e)ii
(e)i Lateral view
Anteroposterior view



Humerus Radius



Humerus
Lateral
Medial
epicondyle Capitulum
epicondyle

Capitulum
Trochlea
Olecranon
Ulna
Radius and
radial head
Ulna
Fig. 12.11. Continued




120
alex m. barnacle and adam w. m. mitchell
The upper limb


The elbow joint increased. A raised anterior fat pad should be interpreted as a fracture
The distal humerus forms the capitulum and the trochlea, which artic- involving the elbow joint, even in the absence of a discernible fracture
ulate with the head of the radius and the trochlear notch of the ulna, line.
respectively, forming a synovial hinge joint (Fig. 12.12). Capsular thick- Careful attention should be paid to the presence and position of the
enings known as the radial and ulnar collateral ligaments strengthen epiphyses following injuries to the elbow in children, so that disloca-
the joint capsule. The joint contains two fat pads. The anterior fat pad tions or fractures involving the growth plates are not missed.
is visualized in approximately 15% of normal joints. The posterior fat Alignment of the epiphyses must also be carefully assessed on plain
pad is only seen when a joint effusion ¬lls the joint space and dis- radiographs. On the lateral view, a line parallel to the anterior cortical
places or elevates the fat pads. line of the humerus should pass through the middle third of the
The movements of the elbow joint are: capitulum (see Fig. 12.12). In a young patient with unfused epiphyses,
a supracondylar fracture through the unossi¬ed growth plate can only
• Flexion: brachialis, biceps, assisted by brachioradialis, pronator
be detected by the abnormal alignment of the humeral shaft with the
teres
capitulum.
• Extension: triceps.

The movements of the radioulnar joints are:
Musculature of the forearm
The anterior compartment of the forearm contains several muscle
• Supination: biceps, supinator
groups, including pronator quadratus and pronator teres, the wrist
• Pronation: pronator teres, pronator quadratus.
¬‚exors, and the long ¬‚exors of the ¬ngers and thumb, many of which
arise from the common ¬‚exor origin on the anterior aspect of the
Imaging of the elbow joint medial epicondyle of the humerus. The posterior compartment
Standard radiographic views of the elbow comprise lateral and antero- includes brachioradialis and the long extensors of the wrist and hand,
posterior projections. The radial head view isolates the radial head so some of which arise from the common extensor origin on the anterior
that the conspicuity of radial head fractures, which are often occult, is aspect of the lateral epicondyle of the humerus.
Pronator teres arises from the common ¬‚exor origin and the coro-
noid process of the ulna, and inserts onto the lateral surface of the
Anteroposterior view shaft of the radius.
Groove for
Flexor carpi radialis arises from the common ¬‚exor origin and
olecranon
fossa
inserts onto the base of the second and third metacarpals.
Palmaris longus extends from the common ¬‚exor origin to the
¬‚exor retinaculum. It is a vestigial muscle and is often absent.
Medial epicondyle
Flexor digitorum super¬cialis arises from the common ¬‚exor origin,
the ulna collateral ligament, the coronoid process, and the radial
head, and passes deep to the ¬‚exor retinaculum. Its tendons decussate
to insert onto the sides of the middle phalanx of each digit.
Capitulum
Trochlea
radial head
Flexor carpi ulnaris arises from the common ¬‚exor origin and the
posterior border of the ulna, inserting onto the pisiform, the hamate
Coranoid
and the medial aspect of the base of the ¬fth metacarpal.
process
Flexor pollicis longus arises from the anterior surface of the radius,
Ulna passes deep to the ¬‚exor retinaculum, and inserts onto the base of the
distal phalanx of the thumb.
Flexor digitorum profundus arises from the anterior and medial
aspects of the ulna. Its four tendons pass deep to the ¬‚exor retinacu-
lum, traverse the decussation of the ¬‚exor digitorum super¬cialis and
insert onto the base of the terminal phalanx of each ¬nger.
Pronator quadratus is a broad, ¬‚at muscle deep in the forearm,
running between the anterior surfaces of the radius and ulna.
Lateral view
Brachioradialis arises from the lateral supracondylar ridge of the
Radius
humerus and inserts onto the lateral aspect of the distal radius.
Radial head Coronoid
Extensor carpi radialis longus arises from the lateral supracondylar
process
ridge of the humerus and inserts onto the base of the second
metacarpal.
Extensor carpi radialis brevis arise from the common extensor
origin and inserts onto the dorsal aspect of the base of the third
Distal humerus
metacarpal.
Extensor digitorum arises from the common extensor origin and
Olecranon process Ulna
of the ulna
forms four tendons distally in the forearm, which pass deep to the
¬‚exor retinaculum in a single synovial sheath. The tendons attach to
the bases of the middle and distal phalanges of the ¬ngers.
Fig. 12.12. Standard anteroposterior and lateral radiographic views of the elbow.


121
alex m. barnacle and adam w. m. mitchell
The upper limb


Extensor digiti minimi passes from the common extensor origin to
the dorsal aspect of the little ¬nger.
Extensor carpi ulnaris arises from the common extensor origin and
the posterior aspect of the ulna and attaches to the ulnar side of the
base of the ¬fth metacarpal.
The supinator arises from the common extensor origin and the pos-
terior aspect of the ulna. The muscle passes laterally, wrapping around
the upper end of the radius to attach to its anterior surface, forming
part of the ¬‚oor of the antecubital fossa.
The abductor pollicis longus arises from the posterior aspect of the
radius and ulna, and passes laterally, to attach to the radial side of the
base of the ¬rst metacarpal.
The extensor pollicis brevis also arises from the posterior aspect of
the radius and ulna, and accompanies abductor pollicis longus to
attach to the base of the proximal phalanx of the thumb.
The extensor pollicis longus arises from the posterior aspect of the
ulna, passes deep to the extensor retinaculum and attaches to the base
of the distal phalanx of the thumb. Extensor indicis arises from the
posterior aspect of the ulna and attaches to the dorsal aspect of the
index ¬nger.


The wrist and hand
The hand
The proximal portion of the hand is made up of the bones of the
carpus, part of which articulates with the bases of the metacarpals.
There are eight carpal bones arranged in two rows (Fig. 12.13). The
proximal row contains three carpal bones: the scaphoid, lunate, and
Metacarpals
triquetral (lateral to medial). The distal row comprises four bones: the
trapezium, trapezoid, capitate, and hamate (lateral to medial). The Trapezium Hook of hamate
pisiform is a sesamoid bone, which overlies and articulates with the Hamate
Trapezoid
triquetral bone in the proximal carpal row. The palmer surfaces of
Lines of congruence
pisiform and hamate give attachment to ¬‚exor carpi ulnaris; several Capitate
small muscles of the hand take their origins from both the dorsal and Triquetral

palmer surfaces of the carpal bones. Scaphoid
Pisiform
The con¬guration of the carpal bones creates a palmer concavity
Lunate
or tunnel, bridged by a ¬brous strap or retinaculum, which
attaches medially to the pisiform and hook of hamate, and laterally Ulna
Radius
to the scaphoid tubercle and trapezium. This carpal tunnel contains
several of the ¬‚exor tendons and the median nerve. MRI and, less
commonly, ultrasound, are used to assess the soft tissues of this Fig. 12.13. Standard anteroposterior radiograph of the wrist.
region (Fig. 12.14).
The bases of the ¬ve metacarpals articulate with the distal carpal
row and with each other via synovial joints. The synovial capsules of
the carpometacarpal joints are thickened to form the deep transverse
ligaments of the palm. The heads of the metacarpals articulate with
the proximal phalanges. There are two phalanges in the thumb and
three in each of the ¬ngers. For the sake of clarity, the digits are best
labeled as thumb, index ¬nger, middle ¬nger, ring ¬nger, and little
¬nger. The interphalangeal joints all form synovial hinge joints. The
shafts of the metacarpals give attachment to the small interossei
muscles of the hand, opponens pollicis, and adductor pollicis; the
phalanges give attachment to the long ¬‚exors and extensors of the
digits.
The ¬rst metacarpal is rotated on its long axis and has a saddle-like
con¬guration to the articular surfaces of the carpometacarpal joint.
Flexion and extension therefore occur at right angles to the move-
ments of the other digits. Speci¬cally, this also allows opposition of Fig. 12.14. Gradient echo MR image through the wrist, demonstrating the carpal
the thumb and index ¬nger. tunnel and the tendons within it.


122
alex m. barnacle and adam w. m. mitchell
The upper limb


(c)
As in the elbow, the bones of the carpus ossify at different times
and knowledge of the sequence is important both in wrist injuries
in children and in the assessment of bone age (see later). The timing
of ossi¬cation of the carpal bones is relatively predictable. The
capitate and hamate ossify in the ¬rst year of life, the triquetral in
the second year, the lunate in the third, the scaphoid, trapezium
and trapezoid in the sixth year, and the pisiform by the twelfth year
(Fig. 12.15).

Bone age
A child™s skeletal maturity can be assessed and monitored by estimat-
ing the patient™s bone age from the epiphyses of the hand. This can
be critical in patients with endocrine disturbances or limb length
discrepancies. An estimate of bone age is made by comparing the epi-
physes of the left hand against radiographic standards from normal Hamate Capitate

Western populations found in atlases such as Greulich and Pyle (1959). Scaphoid
Triquetral
Of note, bone age is more dif¬cult to estimate in the young child


(a)

(d)




Capitate




Hamate
Capitate
Trapezoid
Hamate
Trapezium
Radius
Triquetral
Ulna
Scaphoid
Lunate


(b)


(e)




Fig. 12.15. Radiographs
of the carpal bones in
the growing child,
Capitate
Capitate
demonstrating
Trapezoid
Hamate
ossi¬cation of the carpal
Triquetral Triquetral Trapezium bones during the ¬rst
12 years of life:
Pisiform
Hamate
Scaphoid
(a) 1 year, (b) 3 years,
Lunate
(c) 5 years, (d) 7 years,
(e) 12 years.


123
alex m. barnacle and adam w. m. mitchell
The upper limb




Fig. 12.17. Contrast has been introduced into the radiocarpal and the mid carpal
joint (these joints do not normally communicate). Contrast does not spill into
Fig. 12.16. T1 weighted coronal MR image of the wrist, showing the bones of the
the distal radioulnar joint, con¬rming the triangular ¬brocartilage is intact.
carpus and the low signal triangular ¬brocartilage between the carpus and
the ulna.

• Abduction: extensor carpi radialis longus and brevis, ¬‚exor carpi
due to non-ossi¬cation of the carpal bones at that age; in such cases,
radialis
radiographs and standard tables of the knee are used to calculate
• Adduction: extensor carpi ulnaris, ¬‚exor carpi ulnaris
bone age.
• Circumduction.

The wrist
Imaging of the wrist and hand
The wrist forms a complex synovial joint. On plain radiographs, the
The alignment of the carpus can be disrupted by trauma and should
distal ulna appears shorter than the adjacent radius; a ¬brocartilagi-
be carefully assessed on both anteroposterior and lateral radiographs.
nous disc, known as the triangular ¬brocartilage, ¬lls the space
The lateral view of the wrist is critical as disruption of the carpal
(Fig. 12.16). The distal ulna articulates with the triangular ¬brocarti-
alignment is easily missed on the anteroposterior view. On the lateral
lage, which in turn articulates with the triquetral and lunate. The
radiograph, the lunate should be cupped snugly in the hollow formed
distal radius articulates directly with the scaphoid and lunate. In
by the distal radial articular surface, and the capitate should be con-
extreme ulnar deviation of the wrist, the radius has some articulation
gruent with the concave distal surface of the lunate (Fig. 12.18). When
with the triquetral. Medial and lateral collateral ligaments thicken the
a fracture of the scaphoid is suspected, multiple supplementary views
joint capsule. The triangular ¬brocartilage is entirely intracapsular.
may help to avoid missing a subtle fracture line (Fig. 12.19). Missed
The presence of the ¬brocartilagenous disk and its osseous attach-
scaphoid fractures may have signi¬cant consequences, due to the risk
ments means that the wrist joint should not communicate with the
of avascular necrosis of the bone if the blood supply is disrupted. Any
distal radioulnar joint.
ongoing concerns regarding this diagnosis should be addressed by an
The composite synovial joint formed between the proximal and
isotope bone scan, which elegantly demonstrates the local blood
distal carpal rows is known as the midcarpal joint and it is here that
supply to the scaphoid bone.
much of the ¬‚exion and extension of the wrist occurs. Interosseous
Ultrasound of the wrist and hand is valuable in assessing the
ligaments separate the two rows of carpal bones, so that, in the
super¬cial tendons sheaths and tendons. MRI plays an increasingly
majority of people, the radiocarpal and midcarpal joints do not com-
central role in detailed examination of this region.
municate (Fig. 12.17).
The movements of the wrist take place at the radiocarpal, mid-
Vascular supply of the upper limb
carpal, and carpometacarpal joints together. They are:

Arterial supply
• Flexion: ¬‚exor carpi ulnaris, ¬‚exor carpi radialis
The upper limb is supplied by the subclavian artery, which becomes
• Extension: extensor carpi radialis longus and brevis, extensor carpi
the axillary artery where it crosses the lateral border of the ¬rst rib.
ulnaris

124
alex m. barnacle and adam w. m. mitchell
The upper limb


within the antero-lateral aspect of the forearm, accompanying a
Fig. 12.18. Standard
lateral radiograph of super¬cial branch of the radial artery throughout its course. It gives
the wrist. The lines
supply to the musculature of the forearm, the elbow, and the wrist
represent the
joints. At the wrist it crosses onto the dorsal aspect of the hand, where
orientation of the lunate
it overlies scaphoid, passing through the ¬rst dorsal interosseus
with the distal radius
muscle to form the deep palmer arch of the hand. A small branch of
and the capitate.
the radial artery contributes to the super¬cial palmer arch. The deep
palmer arch gives rise to the palmer metacarpal arteries,
The ulnar artery lies within the medial aspect of the anterior com-
partment of the forearm, accompanying the ulnar artery. It too sup-
plies forearm muscles, the elbow, and wrist. Its largest branch is the
interosseous artery, which arises just beyond the origin of the ulnar
artery; its anterior and posterior divisions are intimately related to the
interosseous membrane within the forearm. Distally, the ulnar artery
crosses the anterior aspect of the wrist super¬cial to the ¬‚exor reti-
naculum and terminates adjacent to the pisiform bone of the carpus,
forming the super¬cial palmer arch of the hand. In a similar pattern
to the radial artery, it has a small supply to the deep palmer arch. The
super¬cial palmer arch gives rise to digital arteries, which bifurcate to
supply the medial and lateral aspects of adjacent digits (Fig. 12.21).
Imaging of the upper limb vessels may be critical in cases of major
trauma to the upper limb, particularly at the shoulder where the axil-
lary artery is closely applied to the surgical neck of the humerus.
Although contrast-enhanced CT examinations reconstructed to give
images that are termed CT angiograms may delineate the major vascu-
lar structures of the limb, traditional catheter angiography in an inter-
ventional radiology suite allows far greater detail and provides an
Metacarpals
opportunity for endovascular treatment of vessel trauma by the inter-
ventional radiologist at the time of the examination.

Venous drainage
1st meatcarpal The upper limb is drained by deep and super¬cial veins. The veins of
Capitate
the hand form an intricate super¬cial dorsal venous network and a
Trapezium
Lunate
deeper palmar network. These drain into the super¬cial veins of the
Scaphoid
forearm, the largest of which are the basilic and cephalic veins, lying
medially and laterally, respectively. Deep perforator veins from the
Radius and ulna
muscles of the forearm anastamose with these forearm veins. At the
elbow, the smaller super¬cial vessels drain into the cephalic and
basilic veins. The basilic vein lies medial to the brachial artery and to
biceps within the upper arm, and pierces the deep fascia to join the
deep brachial vein within the axilla. The smaller cephalic vein, which
lies super¬cially within the anterolateral aspect of the upper arm,
becomes more anterior in position at the shoulder. The vessel follows
At the lower border of teres major, which marks the inferior bound-
the anterior border of deltoid and inserts into the axillary vein after
ary of the axilla posteriorly, the axillary artery becomes the brachial
artery (Fig. 12.20). The axillary artery gives off several branches piercing the clavipectoral fascia in the groove between the bellies of
pectoralis major and deltoid, the deltopectoral groove (Fig. 12.22).
before becoming the brachial artery; the branches are best remem-
The deep veins of the forearm form the brachial vein above the
bered by dividing the axillary artery into three segments. The ¬rst
segment gives off one branch, the superior thoracic artery; the elbow, which accompanies the brachial artery within the anterior
compartment of the upper arm and becomes the axillary vein at the
second segment gives off two branches, the acromiothoracic artery
lower border of teres major.
and the lateral thoracic artery; the third segment has three branches,
These veins are increasingly commonly used for placement of non-
the subscapular artery, and the anterior and posterior circum¬‚ex
tunnelled long-term venous access catheters (peripherally inserted
humeral arteries, which supply the shoulder and form an anastamo-
sis around the surgical neck of the humerus. The brachial artery con- central venous catheters, PICCs) and are amenable to ultrasound
guided puncture.
tinues to the elbow, lying antero-medially within the anterior ¬‚exor
compartment of the upper arm, medial to biceps, and its tendon,
giving off small perforators to the surrounding musculature, the
Nerve supply of the upper limb
elbow joint, and humerus.
Within the antecubital fossa, the brachial artery divides into the The upper limb receives its innervation from the anterior divisions or
radial and ulnar arteries. The radial artery lies deep to brachioradialis rami of the lower four cervical and the ¬rst thoracic nerves. These

125
alex m. barnacle and adam w. m. mitchell
The upper limb




Fig. 12.19. Standard radiographic projections used to demonstrate the scaphoid bone and ensure that it is clearly visualized in all planes.


form the ¬ve roots of the brachial plexus, which lies between the overlying skin. At the elbow, the radial nerve lies antero-laterally, and
anterior and middle scalene muscles of the neck. The roots of the descends the arm deep to the brachioradialis and lateral to the radial
brachial plexus undergo further complex divisions and fusions to artery. Its largest branch is the posterior interosseous nerve, which
¬nally form three distinct cords: the lateral, posterior, and medial pierces the supinator to supply the extensor compartment of the
cords. These are named according to their intimate relationship to the forearm. At the wrist, the radial nerve accompanies the radial artery
axillary artery as they exit the axilla. onto the dorsal aspect of the hand, to give its terminal digital divi-
The posterior cord gives innervation to many of the muscles of the sions. The radial nerve supplies the extensor muscles of the upper
rotator cuff, to the larger muscles of the shoulder and to the shoulder limb, the elbow, wrist, and intercarpal joints, and the lateral aspect of
joint, and then divides to form the radial and axillary nerves. the dorsum of the hand, including the dorsal surfaces of the lateral
two digits and the middle ¬nger.
Radial nerve
Musculocutaneous nerve
The radial nerve lies posteriorly within the axilla. It descends the arm
in the radial groove of the humerus, deep to the medial and lateral The musculocutaneous nerve arises from the lateral cord of the
heads of triceps, supplying the extensor muscles of the upper arm and brachial plexus and lies anteriorly within the upper arm, between

126
alex m. barnacle and adam w. m. mitchell
The upper limb


(a) (b)




Fig. 12.20. Catheter angiogram images of the right axillary artery: (a) the bony structures of the shoulder have been superimposed on the image to aid orientation,
(b) the bony detail of the image has been digitally subtracted to allow clearer visualization of the vascular anatomy. The catheter tip lies just beyond the origin of
the axillary artery. Note that the patient has a right-sided central venous catheter in situ.




biceps and brachialis, before becoming the lateral cutaneous nerve of
the forearm.

Median nerve
The median nerve arises from both lateral and medial cords of the
brachial plexus and accompanies the brachial artery in the medial
portion of the anterior compartment of the upper arm. It passes
medial to the brachial artery in the antecubital fossa and continues in
the anterior compartment of the forearm, giving off its ¬rst branch,
the anterior interosseous nerve, which descends on the anterior
surface of the interosseous membrane. The median nerve enters the
wrist deep to the ¬‚exor retinaculum and ends by dividing into digital
branches overlying the carpus. The median nerve and its branches
supply most of the forearm ¬‚exors and the small muscles of the
thenar eminence. It supplies the skin of the radial aspect of the hand,
including the palmer surfaces of the lateral three digits and the lateral
surface of the index ¬nger.

Ulnar nerve
The ulnar nerve arises from the medial cord of the brachial plexus. It
initially follows the course of the median nerve and brachial artery.
It then pierces the intermuscular septum of the upper arm to exit
the anterior compartment and continue, without branching, adjacent
to the medial head of triceps, passing posterior to the medial epi-
condyles of the humerus at the elbow. Distal to this, the ulnar nerve
Fig. 12.21. Digitally subtracted catheter angiogram of the super¬cial palmer arch
lies within the medial aspect of the ¬‚exor compartment of the
of the hand. Contrast medium has been injected into the ulnar artery and
forearm, deep to the ¬‚exor carpi ulnaris. It passes super¬cial and
opaci¬es the digital vessels. Some contrast has re¬‚uxed into the radial artery.


127
alex m. barnacle and adam w. m. mitchell
The upper limb


(a) (b)




Fig. 12.22. Digitally subtracted venogram images of the left shoulder. Iodinated
contrast medium has been injected into a distal super¬cial vein: (a) contrast
outlines the cephalic vein and re¬‚uxes into the origin of the left internal jugular
vein. Note the bulging contour of the brachial vein at the sites of the venous
valves. Incidental left superior vena cava noted; (b) in this patient, the brachial
vein is occluded. Contrast injected via the distended cephalic vein re¬‚uxes into
the occluded brachial vein. Information such as this is useful in planning the
placement of peripheral venous catheters.




medial to the ¬‚exor retinaculum at the wrist, dividing into small mus- The deep lymph node group, draining the deep muscle and bone,
cular and cutaneous branches in the hand. The ulnar nerve supplies run along the deep veins of the upper limb and drain into the lateral
some of the ¬‚exors of the forearm, most of the small muscles of the group of axillary nodes.
hand, the medial half of the dorsum of the hand, and the medial two Nuclear medicine studies can be performed to assess the lymphatic
digits and part of the middle ¬nger. drainage of a limb, by intradermal injection of a radioisotope; radioac-
tivity is then traced through the lymphatic chain, using a gamma
camera. This technique is fast becoming obsolete, given the exquisite
Lymphatic drainage of the upper limb
detail of the soft tissues and lymph nodes now available on MR and US
The major super¬cial lymph node groups in the upper limb are the imaging.
cubital nodes, which are closely related to the medial aspect of the
basilic vein, the axillary nodes, which surround the axillary vein, and Further reading
1 Greulich, W.W. and Pyle, S. (1959) Radiographic atlas of skeletal development of the
the deltopectoral node, which lies adjacent to the cephalic vein ante-
hand and wrist, 2nd edn. Stanford University Press, 1959.
rior to the shoulder. The deltopectoral node drains into the infraclavic-
ular nodes and then to the axillary nodes.




128
Section 5 The limbs

Chapter 13 The lower limb


A. NEWMAN SANDERS




Angiography
Imaging methods
Catheter angiography is still used extensively to treat abnormalities of
the arterial system, but for purely diagnostic purposes is being super-
The bony pelvis and lower limb are increasingly examined using the
seded by CT or MR angiography. Ascending venography, commonly
full armoury of imaging modalities as these become more widely
used in the past for diagnosis of deep vein thrombosis has been
available.
almost completely replaced by Colour Doppler US.
Plain radiography
Plain radiography remains as important as ever, and its more detailed
The bony pelvis and hip joint
applications will be discussed further in the relevant anatomical sub-
The bony pelvis consists of a ring formed by the paired innominate
sections.
bones, the sacrum and the coccyx, (Fig. 13.1). The ring is completed
Computed tomography (CT) by the paired sacroiliac joints posteriorly and the pubic symphysis
anteriorly.
CT is especially useful in complex skeletal trauma, using three-
The innominate bones are composed of three parts: the ilium,
dimensional reconstructions to contribute valuable additional
ischium, and pubis. These meet at the triradiate cartilage, visible in
information.
the immature skeleton as a Y-shaped irregular lucency at the
Magnetic resonance imaging (MRI) acetabulum.
The ilium is a curved, ¬‚at bone with the iliac crest superiorly. At
MRI has revolutionized the investigation of bone, joint, and soft tissue
either end of the crest are the anterior and posterior superior iliac
abnormalities. Multiplanar imaging capability and high contrast reso-
spines. Below these lie the anterior and posterior inferior iliac spines,
lution mean that the presence and extent of pathology can be de¬ned
respectively.
far more accurately.
The ischium has a body with a tuberosity inferiorly. From this, the
Ultrasound ischial ramus runs anteriorly to join the inferior pubic ramus at a syn-
chondrosis. Posteriorly, the ischial spine divides the greater sciatic
Ultrasound is commonly used to investigate the musculoskeletal
notch above from the lesser sciatic notch below.
system. High frequency (7.5“10 mHz) probes can obtain excellent reso-
The pubis consists of a body and superior and inferior rami.
lution of the internal architecture of tendons, ligaments, and muscles.
The sacrum is formed by the fusion of the ¬ve sacral vertebrae. Its
Other applications include the detection of ¬‚uid collections around
concave anterior surface forms a hollowed posterior wall to the true
joints and the initial assessment of soft tissue masses and cysts.
pelvis. Its broad base lies superiorly supporting the spinal column.
Nuclear medicine Inferiorly, its apex articulates with the coccyx, a triangular bone
formed from the fusion of the four coccygeal vertebrae (occasionally
99 m Technetium methylene diphosphonate is the commonest isotope
three or ¬ve).
in routine use and is administered intravenously. The bone scan is
Laterally the roughened auricular (“ear-shaped”) surfaces of the
very sensitive to the presence of any pathology but is relatively non-
sacrum articulate with the iliac bones. The sacral canal is a continua-
speci¬c. Areas of increased uptake (“hot spots”) are due to both
tion of the spinal canal and transmits the lower spinal nerve roots.
increased blood supply and increased osteoblast activity and may be
The ventral rami exit via four paired anterior foraminae, the dorsal
seen in fractures, malignancy, soft tissue, and bony infection, and
rami via the dorsal foraminae. The pelvis is divided into the true and
joint disease. Labeled white cells can also be used to assess infections
false pelvis by the pelvic brim or inlet, which consists of the sacral
of the bones and soft tissues.

Applied Radiological Anatomy for Medical Students. Paul Butler, Adam Mitchell, and Harold Ellis (eds.) Published by Cambridge University Press. © P. Butler,
A. Mitchell, and H. Ellis 2007.
129
The lower limb a. newman sanders



Sacral crest Iliac crest
Anterior superior iliac spine

Anterior
sacral
foramen


Sacroiliac
joint


Iliopectineal
Calcification
line
in vestigeal
intervertebral
Anterior
disc
inferior
iliac spine

Phleboliths

Hip joint
Ischial
spine
Greater
trochanter
Head of
femur




Neck of
femur



Bladder
Inferior
Ischial Superior Obturator
pubic
ramus pubic foramen
ramus ramus
Ischial
tuberosity Fig. 13.1. Frontal
Lesser Symphysis
trochanter pubis radiograph of an adult
female pelvis.



Fig. 13.3. Ossi¬cation of
the bones of the pelvis.
The secondary centres
(hatched) start to ossify
at puberty and fuse at
20“25 years.
More prominent
Prominent
sacral promontory
muscle Iliac crest
attachments Ilium
More prominent Acetabular
8 weeks
ischial spines cup
Narrower
pelvis
inlet

Ischial
tuberosity
Pubis
Longer sacrum
18“22
with relatively
Narrower Ischium
weeks
narrow inlet
pubic arch 18“22
weeks

Fig. 13.2. Frontal radiograph of an adult male pelvis. Note the differences
between this radiograph and that of the female pelvis illustrated in Fig. 13.1.



promontory, ilio-pectineal lines, and symphysis pubis. The pelvic Three accessory ligaments also contribute to the stability of the
outlet is bounded by the coccyx posteriorly, the ischial tuberosities posterior part of the pelvic ring.
laterally, and the inferior pubic arch anteriorly.
The symphysis pubis
The sacroiliac joints This is a secondary cartilaginous joint, consisting of both hyaline and
These are synovial joints between the auricular surfaces of the sacrum ¬brocartilage. (Primary cartilaginous joints contain only hyaline carti-
and iliac bones. The iliac surface is covered with hyaline cartilage, lage.) Each articular surface is covered with a layer of hyaline cartilage
the sacral surface by ¬brocartilage. A small amount of rotatory move- enclosing a ¬brocartilaginous disk. The whole joint is covered by
ment occurs at the joint, which is increased in pregnancy and child- dense ligaments. Virtually no movement is possible at the joint.
bearing. The joint is strengthened by the ventral and dorsal sacroiliac There are some gender differences in the appearance of the pelvis
ligaments and particularly by the interosseous sacroiliac ligament visible on plain radiographs (Fig. 13.2).
which occupies the area immediately above and behind the joint. Ossi¬cation of the pelvis is demonstrated in Fig. 13.3.

130
The lower limb a. newman sanders


The hip joint • adduction: adductor longus, brevis and magnus, pectineus, and
This is a synovial articulation of the “ball and socket” type between gracilis;
the head of the femur and the acetabulum. The articular cartilage is • medial rotation: anterior ¬bers of gluteus medius and minimus,
thickest and broadest superiorly where the weight is borne. The fovea tensor fascia lata;
capitis, where the ligament of the head (ligamentum teres) is • lateral rotation: obturator muscles, gemelli, quadratus femoris,
attached, is not covered in cartilage. The articular surface of the piriformis, gluteus maximus, and sartorius.
acetabulum is de¬cient inferiorly over the acetabular notch and cen-
A brief outline of the attachment of the most important muscles of
trally where the ¬‚oor of the acetabulum is ¬lled with a ¬berofatty
the lower limb is given below to supplement the images and diagrams
pad. The ¬brocartilaginous acetabular labrum serves to deepen the
of the cross-sectional anatomy (Fig. 13.5).
articular cup. It bridges the acetabular notch as the transverse acetab-
Gluteus maximus arises from the superior part of the posterior
ular ligament. The ¬brous capsule is attached around the rim of the
surface of the ilium including the crest, the side of the sacrum,
acetabulum and inferiorly to the transverse acetabular ligament. It is
coccyx, and sacrotuberous ligament. The majority of the muscle con-
reinforced by three ligaments (Fig. 13.4). Its femoral attachments are
verges as a tendinous sheet to merge with the iliotibial tract. The
to the base of the neck and to the inter-trochanteric line.
deeper ¬bers attach to the gluteal tuberosity of the femur. Gluteus
The capsular retinaculum is made up of ¬bers that are re¬‚ected
medius arises deep to, and below, gluteus maximus and attaches to
proximally along the neck. It carries an important part of the blood
the lateral aspect of the greater trochanter. Gluteus minimus arises
supply to the femoral head and neck.
below, and deep to, gluteus medius and is completely covered by it. It
The synovium arises from the margins of the articular cartilage of
is attached to the anterior surface of the greater trochanter.
the femoral neck and covers the intracapsular femoral neck, the inner
Piriformis arises from the front of the sacrum and from the gluteal
surface of the capsule, the acetabular labrum, the ¬brofatty pad ¬lling
surface of the ilium. It passes out of the pelvis through the greater
in the ¬‚oor of the acetabulum and is re¬‚ected as a tube sheathing the
sciatic foramen and inserts on the upper border of the greater
ligamentum teres. It may communicate with a bursa beneath the
trochanter.
tendon of psoas major through a de¬ciency in the ¬brous capsule and
Obturator internus arises from the pelvic surface of the medial part
iliofemoral ligament.
of the obturator membrane and the surrounding bone and passes
The movements of the hip joint are
through the lesser sciatic foramen. Its tendon receives the ¬bers of the
• ¬‚exion: iliacus, psoas major, pectineus, rectus femoris, and sartorius; gemelli muscles and inserts at the medial surface of the greater
• extension: gluteus maximus and the hamstrings; trochanter.
• abduction: gluteus medius and minimus, tensor fascia lata, and Obturator externus takes its origin from the outer surface of the
sartorius; obturator membrane and the surrounding bone and passes below the
hip joint to insert at the base of the medial surface of the greater
trochanter.
Plain radiography relies mainly on the anteroposterior (AP) view
(a)
(Fig. 13.6), and several landmarks should be identi¬ed. Shenton™s line
Anterior inferior
iliac spine
is a smooth curve running from the medial aspect of the femoral neck
Iliopectineal
eminence
Iliofemoral
to the superior border of the obturator foramen. The iliopectineal line
ligament
and ilio-ischial lines should also be smooth symmetrical arcs.
The posterior and anterior rims of the acetabulum and the acetabu-
lar “teardrop” are also illustrated. Kohler™s “teardrop distance” should
be less than 11 mm, and there should not be a difference of more than
2 mm between the two sides.
Intertrochanteric
line
Ischial tuberosity Pubofemoral
Imaging of the pelvis and hips
ligament
Lesser trochanter
A lateral ¬lm is often required to rule out subtle fractures of the
femoral neck (Fig. 13.6). A “frog” lateral is sometimes obtained using

(b)
Ischiofemoral
Common femoral
Psoas
ligament
artery and vein Femoral head
Sartorius
Rectus
Greater
trochanter femoris

Tensor
fascia lata

Gluteus
medius
Ischial
tuberosity

Region of
loose attachment
of capsule
Lesser
Fig. 13.4. The ligaments Gluteus maximus Obturator internus Prostate
trochanter
of the right hip joint,
Intertrochanteric crest
(a) anterior, (b) posterior. Fig. 13.5. Proton density axial MRI: the hip joints


131
The lower limb a. newman sanders


of hip prostheses, especially in the context of possible loosening.
Fig. 13.6. AP and lateral
(a)
Radiographs of the right Arthrography also increases the accuracy of MR in detecting labral
Anterior hip, (a) anteroposterior, tears and small articular cartilage defects.
superior
(b) lateral.
iliac spine

Pelvimetry
Inferior
It is occasionally necessary to assess the female pelvis radiologically to
superior
iliac spine
assess the likelihood of dif¬culties in labor.
Fovea
capitis
MRI should be used if available as it imparts no radiation dose. CT
Femoral head
Acetabular pelvimetry is more commonly used, especially outside pregnancy, and
teardrop
is performed using a lateral scout view and measuring the inlet and
Greater
trochanter Shenton™s
outlet diameters in the sagittal plane.
line
¤
¤



The most important measurement is the AP inlet or conjugate diam-
eter, which is the smallest AP diameter between the posterior
margin of the symphysis pubis and the anterior aspect of the sacrum,
(Fig. 13.7). The normal value varies between 11.0 and 12.5 cm. Values of
Femoral Body
less than 10.5 cm indicate increasing likelihood of cephalopelvic dis-
neck Obturator
Superior
foramen
proportion.
Ischial ramus of
tuberosity Inferior pubis
Lesser ramus
trochanter

The thigh
(b)
The femur
Ischial spine
The femur (Fig. 13.8), consists of a shaft, a neck, and a head, which
articulates with the acetabulum. The patella is a ¬‚attened sesamoid
Acetabulum Vascular
calcification
bone within the quadriceps tendon. Ossi¬cation is shown in Fig. 13.9.

The muscles of the thigh (Fig. 13.10)
Anterior femoral muscles
Tensor fascia lata arises from the anterior superior iliac spine (ASIS)
Head of femur and is inserted into the iliotibial tract, a strong thickened band of the
deep fascia of the lateral aspect of the thigh (fascia lata), which is
Greater
trochanter
Neck of femur attached distally to Gerdy™s tubercle on the antero-lateral condyle of
the tibia.
Sartorius is a narrow strap muscle arising from the ASIS, which
Lesser
descends diagonally across the front of the thigh to the medial aspect
trochanter
of the knee, where it inserts on the medial tibial condyle.
Shaft of
Quadriceps femoris is made up of four components. Rectus femoris
femur
arises by a straight head from the anterior inferior iliac spine (AIIS) and
a re¬‚ected head from the superior margin of the acetabulum and the
capsule of the hip joint. Its tendon inserts into the superior border of
the patella. Vastus intermedius arises from the anterior surface of the
femoral shaft and inserts into the superior border of the patella deep to
an AP radiograph with the hip abducted and externally rotated so the tendon of rectus femoris. Vastus lateralis arises from the greater
that the knee is lying nearly on the table top. The frog lateral is trochanter and the upper part of the linea aspera. Its distal tendon
particularly useful in assessing the femoral capital epiphyses in chil- inserts into the outer border of the patella and blends with the iliotibial
dren and comparing one side with the other. Other views occasionally tract. Vastus medialis arises from the lower part of the greater
used include oblique (Judet™s) views of the acetabulum and pelvic inlet trochanter and the anterior surface of the femur. Its tendon inserts into
and outlet views in cases of pelvic trauma. the medial side of the patella. The patellar retinacula are expansions of
Ultrasound is able to detect small amounts of ¬‚uid within the joint; the distal tendons of vastus medialis and lateralis.
the anterior surface of the femoral neck within the joint capsule is
accessible to high resolution scanning.
CT is particularly useful in the evaluation of complex bony injuries
of the pelvis, sacro-iliac joints and for identifying bony fragments in A
the acetabulum.
MRI is increasingly being used to make the early diagnosis of avas- C
Fig. 13.7. Measurements
cular necrosis of the hip, a condition for which MR has a high sensitiv-
obtained during CT. AB =
E
ity and speci¬city. It is also able to characterize the soft tissues, B
conjugate inlet
F D
ligaments, and the acetabular labrum. diameter; EF = conjugate
Arthrography is rarely necessary, although it is often helpful if com- outlet diameter
bined with manual or digital subtraction techniques in the assessment pelvimetry.


132
The lower limb a. newman sanders


Fig. 13.8. The right femur,
(a) (b)
Fovea capitis Greater
(a) anterior, (b) posterior.
trochanter
Head
Head
Greater Trochanteric
trochanter fossa
Neck
Neck
Intertrochanteric line
Quadrate
Intertrochanteric
tubercle
crest
Lesser trochanter
Lesser
trochanter




Linea aspera
Shaft




Medial Lateral
supracondylar supracondylar
line line



Adductor
Popliteal surface
Adductor
tubercle
Lateral tubercle
condyle Intercondylar
Medial fossa
epicondyle
Lateral
Lateral condyle
Medial condyle
epicondyle
Medial
condyle
Patellar surface




(a)




(a)
Femur
Vastus intermedius Rectus femoris Vastus medialis
14th year
Puberty
4th year
1st year


Vastus lateralis Superficial
femoral
artery
and vein


Sartorius


(b) Gracilis



Adductor
longus




Fig. 13.9. (a) Ossi¬cation of femur. The secondary centres fuse with the shaft
at 18“20 years; (b) bipartite and multipartite patellae.

Semimembranosus

The adductor muscles
Gracilis arises from the body and inferior ramus of the pubis and
passes down the medial aspect of the thigh over the medial femoral Short head of biceps Long head of biceps Semitendinosus
condyle to insert into the medial surface of the tibia below the
condyle. Pectineus is a ¬‚at, quadrilateral muscle arising from the Fig. 13.10. IW MRI of the right thigh: (a) axial scan through mid-thigh and
pubis; it passes posterolaterally to insert between the lesser (b) coronal image.


133
The lower limb a. newman sanders


the femur. The tibiofemoral compartments are each divided by a ¬bro-
(b)
cartilaginous meniscus (Fig. 13.11). The medial meniscus is larger and
more semicircular. It is broader and thicker posteriorly. The lateral is
smaller, thicker and forms a nearly complete ring. The anterior and
posterior horns of the menisci are attached to the intercondylar area.
The posterior horn of the lateral meniscus is also commonly attached to
Adductor
Vastus magnus
medialis the medial condyle of the femur by the meniscofemoral ligament. The
transverse ligament joins the anterior ends of the menisci.
Vastus The ¬brous capsule is attached around the margins of the articular
lateralis
surfaces.
Gracilis
The synovial membrane lines the ¬brous capsule, but does not
Shaft of
cover the surfaces of the menisci. It lines the suprapatellar bursa,
femur
which may be regarded as part of the knee joint and lies beneath
Sartorius
quadriceps femoris, extending 7“8 cm above the upper border of the
patella. Below the patella, the synovium is separated from the patellar
tendon by the infrapatellar (Hoffa™s) fat pad.
Posteriorly, the synovium is re¬‚ected anteriorly from the ¬brous
capsule to cover both cruciate ligaments on their anterior and lateral
aspects. Several bursae surround the knee (Fig. 13.12).


Transverse ligament Anterior cruciate
ligament


Lateral meniscus
Fig. 13.10. Continued



Medial
trochanter and the linea aspera. Adductor longus arises from the front meniscus
of the body of the pubis and is inserted by a broad aponeurosis on to
the linea aspera. Adductor brevis takes origin from the inferior ramus
and body of the pubis behind pectineus and is attached between the
lesser trochanter and the linea aspera. Adductor magnus arises from
the inferior ischio-pubic ramus and is attached along the linea aspera,
Posterior cruciate ligament
Posterior meniscofemoral ligament
the medial supracondylar line and by a strong tendon to the adductor
tubercle of the medial femoral condyle. Its distal attachment is inter- Fig. 13.11. The menisci and ligaments of the knee and their attachments
rupted by the adductor hiatus through which the femoral vessels pass
to reach the popliteal fossa, as the popliteal artery and vein. (a)

Tendon of
The hamstrings
quadriceps
Semimembranosus arises by a ¬‚attened “membranous” tendon from
the ischial tuberosity. It has a complex distal attachment to the medial
tibial condyle and the medial surface of the tibia with tendinous
Suprapatellar
expansions over the popliteus muscle to the lateral femoral condyle bursa
(the oblique popliteal ligament) and to the tibial collateral ligament
(the posterior oblique ligament).
Semitendinosus takes origin from the ischial tuberosity. Inferiorly,
Fibrous capsule
its long tendon passes round the medial tibial condyle and over the Subcutaneous
medial collateral ligament to attach to the medial surface of the tibia prepatellar
Anterior cruciate
bursa
posterior to the insertions of gracilis and sartorius. ligament
Biceps femoris arises by a long head from the ischial tuberosity and Infrapatellar (Hoffa™s
fat pad) extending
a short head from the shaft of the femur. Its tendon inserts on to the into infrapatellar fold
head of the ¬bula.
Patellar tendon


The knee joint Deep infrapatellar bursa

The knee is a modi¬ed hinge joint and this synovial joint is the largest
in the body. Although contained within a single joint cavity, the knee
effectively comprises two condylar joints between the femoral and cor- Fig. 13.12. (a) Bursae of the knee joint (sagittal section); (b) Bursae around the
responding tibial condyles and a saddle joint between the patella and knee; sagittal and axial MR arthrogram.


134
The lower limb a. newman sanders


surface of the lateral femoral condyle. It prevents the femur moving
(b)
High signal fluid
backwards on the tibia. The posterior cruciate ligament (PCL) is
distending the
attached to the posterior intercondylar area of the tibia and passes for-
suprapatellar
bursa
wards, upwards, and medially to insert into the anterior part of the
lateral surface of the medial femoral condyle. It is stronger and
shorter than the ACL and limits posterior sliding of the tibia on the
femur.
Movements

• Flexion: biceps, semitendinosus, semimembranosus. The extended
knee is unlocked prior to ¬‚exion by popliteus, whose action is to
rotate the femur laterally on the ¬xed tibia;
• Extension: quadriceps femoris;
• Medial rotation of the flexed leg: semimembranosus and semit-
endinosus;
• Lateral rotation of the flexed leg: biceps femoris.

Imaging of the knee
Fig. 13.12. Continued
Plain radiography (Fig. 13.14), is able to demonstrate the bony contours
of the joint space. The normal tibio-femoral and patello-femoral joint
space is 3 mm. The fat around the joint enables visualization of the
patellar tendon, and allows an assessment of the presence or absence
of a joint effusion. If a horizontal beam lateral radiograph is taken, a
Medial condyle
Patellar surface
fat-¬‚uid level (lipohaemarthrosis) in the suprapatellar bursa indicates
a fracture within the joint. Occult fractures are usually of the tibial
Posterior cruciate
ligament plateau. These may be demonstrated by coronal tomography or by
Lateral condyle

thin slice axial CT with coronal reformatting.
Lateral meniscus
Anterior cruciate
If an abnormality of the patella is suspected, it should be imaged by
ligament
the “skyline” view, a tangential view taken with the knee ¬‚exed. The
Fibular collateral
ligament intercondylar fossa of the lower femur may be imaged by the “tunnel”
Coronary
ligament
view, which is used to detect clinically suspected intra-articular loose
Anterior ligament
bodies (Fig. 13.15).
of head of fibula Medial meniscus
MRI is much the most useful imaging technique (Fig. 13.16). It
demonstrates the joint cavity, menisci, ligaments, and articular carti-
Transverse ligament
lage very well.
Fibula
Tibia Dynamic scanning of the knee is also possible with modern scan-
ners, which allow assessment of patellar tracking.

(a)
Fig. 13.13. Ligaments of the knee Joints.


The knee joint is strengthened by four main ligaments, (Figs. 13.13,
13.16). The medial (tibial) collateral ligament is attached to the medial Patella
epicondyle of the femur and to the medial tibial condyle. It is a
Medial
¬‚attened band, which blends posteriorly with the ¬brous capsule, but condyle Lateral
condyle
anteriorly may be separated from it by a bursa. The posterolateral
complex is made up of the popliteus tendon, biceps tendon, ¬bular Groove for
collateral ligament, arcuate ligament, and popliteo-¬bular ligament. popliteus
tendon
Medial tibial
The lateral (¬bular) collateral ligament is a cord-like structure between plateau
the lateral epicondyle of the femur and the head of the ¬bula.
Lateral
Popliteus muscle arises from the posterior surface of the tibia and tibial
sweeps superolaterally behind the knee joint, where its tendon plateau

pierces the capsule and inserts in the groove on the lateral femoral
condyle. Some of its ¬bers blend with the edge of the lateral Tubercles of Medial
Apex
intercondylar
meniscus. It also gives a slip to the tip of the ¬bula (popliteo-¬bular (styloid
eminence Lateral
process)
of fibula
ligament). Head
Neck
The cruciate ligaments (Figs. 13.13, 13.16), are intracapsular but Shaft
extrasynovial. The anterior cruciate ligament (ACL) passes from the
medial part of the anterior intercondylar area of the tibia upwards,
Fig. 13.14. (a) AP, and (b) lateral radiographs of the knee.
backwards and laterally to insert into the posterior part of the medial

135
The lower limb a. newman sanders


(a)
(b)
Hoffa™s fat
Quadriceps femoris Shaft of femur pad Femur Patella




Patella




Intercondylar fossa
Tibial
tuberosity
Medial and lateral
femoral condyles

Tubercles of
intercondylar
eminence
Patellar Anterior cruciate Posterior cruciate Tibia
tendon ligament ligament
Apex
Head of fibula
Shaft
(b) Posterior cruciate Popliteus
Anterior cruciate ligament ligament tendon



Fig. 13.14. Continued



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