venous network in the hand. It joins the cephalic vein distal to the
nous arch of flexor digitorum superficialis (see Figs 49.10, 49.22). It elbow. A large oblique vein often connects the basilic and cephalic veins
descends with the anterior interosseous artery anterior to the interos-
dorsally in the forearm.
seous membrane, between and deep to flexor pollicis longus and flexor
Basilic vein digitorum profundus (Fig. 49.32), supplying flexor pollicis longus
The basilic vein arises medially in the dorsal venous network of the hand and the lateral part of flexor digitorum profundus (to the index and
(see Figs 46.4, 50.39). It ascends posteromedially in the forearm, inclin- middle fingers). Terminally, the anterior interosseous nerve lies poste-
ing forwards to the anterior surface distal to the elbow, where it is joined rior to pronator quadratus, which it supplies via its deep surface. It also
by the median cubital vein. It then ascends superficially between biceps supplies articular branches to the distal radio-ulnar, radiocarpal and
and pronator teres, and is crossed by filaments of the medial cutaneous carpal joints.
nerve of the forearm that pass both superficial and deep to the vein. The
basilic vein continues as the axillary vein from the lower border of teres Palmar cutaneous branch
major (p. 830). The palmar cutaneous branch starts about 3 cm proximal to the flexor
retinaculum. It runs in a small tunnel in the sheath of flexor carpi
Median vein
radialis before piercing the deep fascia, where it divides into lateral
The median vein of the forearm drains the superficial palmar venous branches that supply the thenar skin and connect with the lateral cuta-
plexus and ascends through the anterior part of the forearm to join neous nerve of the forearm. Medial branches supply the central palmar
either the basilic or the median cubital vein (see Figs 48.34, 49.30). It skin and connect with the palmar cutaneous branch of the ulnar nerve


may divide distal to the elbow to join both veins. (see Figs 46.11, 49.21, 50.35, 50.40A–50.41).
A B C Fig. 49.30 A–C, Variations in the
superficial veins of the left cubital
Cephalic vein
Cephalic vein Cephalic vein fossa. (With permission from
Basilic vein Waschke J, Paulsen F (eds),
Basilic vein Sobotta Atlas of Human Anatomy,
Basilic vein Superficial brachial 15th ed, Elsevier, Urban & Fischer.
artery, variation Copyright 2013.)
Median vein
Median Median Median
of forearm
cubital vein cubital vein cephalic vein
Median basilic vein
Basilic vein Median
vein of forearm
Cephalic vein


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The collateral circulation at the elbow is more robust than that at the
knee. Alternative pathways include the profunda brachii artery, which
accompanies the radial nerve through the lateral intermuscular septum
to become the radial collateral artery. The superior ulnar collateral
artery accompanies the ulnar nerve. In the adult, it may be as wide as
1.5 mm at its origin; hence its regular use as the artery to a free vascular-
ized ulnar nerve graft. The inferior ulnar collateral artery is regularly
seen during medial approaches to the elbow as a vessel that pierces the
intermuscular septum to curl around the humerus between triceps and
bone. On occasion, there is a substantial artery running with the median
nerve. These vessels anastomose with recurrent branches from the ulnar
and radial arteries to form a network that may maintain perfusion of
the hand and the extensor muscles in cases where the brachial artery
has been divided in the lower third of the arm (when there is no associ-
ated fracture or dislocation). Collateral circulation will diminish or
cease altogether if the ulnar or radial nerve is entrapped within the
fracture or compressed by haematoma (Birch 2011, Blakey et al 2009).


Vascular supply and lymphatic drainage
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Ulnar artery Fig. 49.31 A transverse section
through the left forearm at the
Flexor carpi radialis Median nerve
level of the radial tuberosity:
Flexor digitorum superficialis Pronator teres, ulnar head proximal aspect.
Palmaris longus Pronator teres, humeral head
Radial artery
Medial cutaneous
nerve of forearm
Cephalic vein
Lateral cutaneous
nerve of forearm
Brachioradialis
Basilic vein Superficial radial nerve
Extensor carpi
Flexor carpi ulnaris radialis longus
Ulnar nerve
Posterior
interosseous
nerve
Extensor carpi
radialis brevis
Posterior cutaneous
Flexor digitorum profundus nerve of forearm
Ulna Extensor digitorum
Anconeus Radius
Biceps brachii, tendon Supinator
Extensor carpi ulnaris
Flexor digitorum superficialis Median nerve Fig. 49.32 A transverse section through the middle of
the left forearm.
Palmaris longus Flexor carpi radialis
Medial cutaneous nerve of
Flexor pollicis longus
forearm (anterior branch)
Radial artery
Ulnar artery
Superficial radial nerve
Ulnar nerve
Flexor carpi
ulnaris Lateral cutaneous
nerve of forearm
Brachioradialis
Medial cutaneous
Cephalic vein
nerve of forearm
(posterior branch)
Extensor carpi
Basilic vein radialis longus
Flexor digitorum Pronator teres
profundus Radius
Ulna Extensor carpi
radialis brevis
Posterior cutaneous
nerve of forearm
Abductor pollicis longus
Extensor carpi ulnaris
Anterior interosseous
Extensor pollicis longus vessels and nerve
Posterior interosseous artery Extensor digitorum
Posterior interosseous nerve Interosseous membrane
muscular branches and signs may also be present. More distally, it may become entrapped
Muscular branches are given off near the elbow to all the superficial by a thickened bicipital aponeurosis. The other sites of compression are


flexor muscles except flexor carpi ulnaris. The branch to the part of between the superficial and deep heads of pronator teres, and the proxi-
flexor digitorum superficialis that serves the index finger is given off mal fibrous arch of flexor digitorum superficialis.
near the mid-forearm and may be derived from the anterior interos-
Martin–Gruber nerve connection
seous nerve. The median nerve is palpable in the anterior aspect of the
elbow, deep to the bicipital aponeurosis. It is closely related to the
brachial artery in the anterior aspect of the elbow, where it courses Available with the Gray’s Anatomy e-book
anterior to brachialis and medial to the artery.
Median nerve compression Ulnar nerve
The median nerve may be compressed at four sites in the elbow and
forearm. The most proximal is the ligament of Struthers, where, if the The ulnar nerve passes behind the medial epicondyle in a groove where
median nerve is accompanied by the brachial artery, vascular symptoms it is easily palpable (see Figs 49.29, 46.12). It runs through the cubital


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Patients essentially present with one of two syndromes. The anterior
interosseous nerve syndrome presents as a failure of pinch grip due to
weakness of flexor pollicis longus and the radial portion of flexor or
digitorum profundus. This reduces the flexion power of the interphalan-
geal joint of the thumb and the distal interphalangeal joint of the index
finger. The pronator syndrome presents with symptoms and signs that
mimic carpal tunnel syndrome. Patients present with pain and altered
sensation in the radial three and a half fingers of the hand that are
aggravated by activity. However, a Tinel’s sign will be positive over the
proximal forearm, and sensation over the thenar eminence may be
diminished, because the palmar cutaneous branch of the nerve arises
above the carpal tunnel. The clinical presentation may vary in the
presence of a Martin–Gruber anastomosis (Rodriguez-Niedenführ et al
2002).
Most patients will respond to non-operative treatment but those
who fail to do so usually respond well to surgical decompression.
Exploration and decompression should address all the potential areas
of compression.
A motor communicating branch between the median and ulnar nerves
in the forearm occurs in approximately one-quarter of patients. The
most common variant has a branch passing from the anterior interos-
seous to the ulnar nerve. A number of patterns have been described
where branches pass between flexors digitorum superficialis and pro-
fundus, deep to the ulnar artery, to join the ulnar nerve; such branches
may explain the variations in innervation of the intrinsic muscles.


Elbow and forEarm
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6
noITCES
tunnel, between the capsule of the humero-ulnar joint and the overly- usually communicates with the posterior and lateral cutaneous nerves
ing arcuate ligament joining the two heads of flexor carpi ulnaris. It of the forearm.
gives off articular branches to the elbow as it lies between the medial
epicondyle and the olecranon. The ulnar nerve enters the forearm Posterior interosseous nerve
between the two heads of flexor carpi ulnaris, which it supplies by two The posterior interosseous nerve is the deep terminal branch of the
neurovascular pedicles: one arising just distal to the cubital tunnel and radial nerve (see Figs 46.9, 49.21, 49.29). It reaches the back of the
one in the forearm. It is superficial to the posterior and oblique parts forearm by passing round the lateral aspect of the radius between the
of the ulnar collateral ligament. two heads of supinator (see Figs 49.25, 49.26). It supplies supinator
The ulnar nerve descends on the medial side of the forearm on flexor both before entering the muscle and as it passes through it. As it emerges
digitorum profundus (see Fig. 49.32). Proximally, it is covered by flexor from supinator posteriorly, the nerve gives off three short branches to
carpi ulnaris; its distal half lies lateral to the muscle and is covered only extensor digitorum, extensor digiti minimi and extensor carpi ulnaris,
by skin and fasciae. In the upper third of the forearm, the nerve is and two longer branches: a medial branch to extensor pollicis longus
distant from the ulnar artery but, more distally, it comes to lie close to and extensor indicis, and a lateral branch that supplies abductor pollicis
the medial side of the artery. About 5 cm proximal to the wrist, it gives longus and extensor pollicis brevis. The nerve at first lies between the
off the dorsal cutaneous branch. At the wrist, the ulnar nerve passes superficial and deep extensor muscles, but at the distal border of exten-


under the superficial part of the flexor retinaculum (in Guyon’s canal) sor pollicis brevis, it passes deep to extensor pollicis longus and, dimin-
and divides into superficial and deep branches (see Fig. 50.40A). ished to a fine thread, descends on the interosseous membrane to the
dorsum of the carpus. Filaments arising from its flattened termination
Branches in the forearm supply the carpal ligaments and articulations. Articular branches from
muscular branches the posterior interosseous nerve supply carpal, distal radio-ulnar and
some intercarpal and intermetacarpal joints. Digital branches supply
There are two main muscular branches of the ulnar nerve in the forearm.
the metacarpophalangeal and proximal interphalangeal joints.
They arise near the elbow and supply flexor carpi ulnaris and the medial
The distal portion of the nerve lies in a separate fascial sheath in the
half of flexor digitorum profundus.
radial, deep, aspect of the fourth dorsal compartment of the extensor
retinaculum of the wrist, where it is located deep to extensor digitorum
dorsal branch
and extensor indicis.
The dorsal branch of the ulnar nerve continues distally and dorsally,
deep to flexor carpi ulnaris. It perforates the deep fascia and descends Radial nerve compression
along the medial side of the back of the wrist and hand. Its further
Radial nerve compression may occur at several sites in the elbow and
course is described on page 893.
forearm. The most proximal of these is within the radial tunnel at the
level of the radial head, where fibrous bands may be present. More
Palmar cutaneous branch
distally, it has been suggested that branches of the radial recurrent artery
The palmar cutaneous branch of the ulnar nerve arises in mid-forearm, may compress the posterior interosseous nerve. Other sites of compres-
descends on the ulnar artery, which it supplies, and then perforates the sion are the tendinous edge of the deep surface of extensor carpi radialis
deep fascia. It communicates with the palmar branch of the median brevis and the point at which the nerve passes under the arcade of


nerve and ends in the palmar skin. It sometimes supplies palmaris Frohse and between the two heads of supinator. Rarely, the nerve may
brevis. Its further course is described on page 894. be compressed at the level of the distal border of supinator.
Ulnar nerve compression Lateral cutaneous nerve of the forearm
The ulnar nerve may be compressed by the arcade of Struthers at the
level of the medial intermuscular septum or at the level of the flexor/
The lateral cutaneous nerve of the forearm is the cutaneous division of
pronator aponeurosis as it enters the forearm between the heads of
the musculocutaneous nerve (p. 831). It lies between biceps brachii and
flexor carpi ulnaris. It is most often compressed at the level of the
brachialis, inclining from the medial to the lateral side; passes through
cubital tunnel; this is the most common nerve compression syndrome the cubital fossa lateral to the tendon of biceps brachii (see Figs 48.33,
after that of the median nerve in the carpal tunnel.
48.34, 49.31–49.32) and deep to the cephalic vein; and descends along
the radial border of the forearm to the wrist. It supplies the skin of the
Radial nerve anterolateral surface of the forearm (see Fig. 49.1) and connects with
the posterior cutaneous nerve of the forearm and the terminal branch
The radial nerve at the elbow lies in the deep groove between brachialis of the radial nerve by branches that pass around its radial border. Its
medially and brachioradialis and extensor carpi radialis longus laterally trunk gives rise to a slender recurrent branch that extends along the
(see Fig. 49.21). The nerve to brachioradialis arises about three fingers’- cephalic vein as far as the middle third of the upper arm, distributing
breadths proximal to the lateral epicondyle; the nerve to extensor carpi filaments to the skin over the distal third of the anterolateral surface of
radialis longus about one finger’s-breadth more distal; and the nerve to the upper arm close to the vein. At the wrist joint, the lateral cutaneous


extensor carpi radialis brevis about one finger’s-breadth above the epi- nerve of the forearm is anterior to the radial artery. It gives off filaments
condyle. These branches arise from the main radial nerve as it runs that pierce the deep fascia and accompany the artery to the dorsum of
between brachialis and brachioradialis. The nerve may be palpable at the carpus. The nerve then passes to the base of the thenar eminence,
this level. The radial nerve divides into the posterior interosseous and where it ends in cutaneous rami, some of which connect with the ter-
superficial radial nerves anterior to the elbow at the level of the tip of minal branch of the radial nerve and the palmar cutaneous branch of
the lateral epicondyle. Another branch to extensor carpi radialis brevis the median nerve.
is usually given off here. There is some variation in the level at which
branches of the radial nerve arise from the main trunk in different Medial cutaneous nerve of the forearm
individuals. Branches to extensor carpi radialis brevis and supinator
may arise from the main trunk of the radial nerve or from the proximal The medial cutaneous nerve of the forearm has already divided into
part of the posterior interosseous nerve, but almost invariably above anterior and posterior branches before it enters the forearm (see Figs
the arcade of Frohse. 48.34, 49.12, 49.31–49.32). The larger anterior branch usually passes
in front of, or occasionally behind, the median cubital vein, and
Branches in the forearm descends anteromedially in the forearm to supply the skin as far as the
Superficial radial nerve wrist. It curves round to the back of the forearm, descending on its
The superficial radial nerve descends from the lateral epicondyle antero- medial border to the wrist, supplying the skin (see Fig. 49.1). It con-
laterally in the proximal two-thirds of the forearm, initially lying on nects with the medial cutaneous nerve of the arm, the posterior cutane-
supinator, lateral to the radial artery and behind brachioradialis. In the ous nerve of the forearm, and the dorsal branch of the ulnar nerve.


middle third of the forearm, it lies behind brachioradialis, close to the
Posterior cutaneous nerve of the forearm
lateral side of the artery. It runs anterior to pronator teres, the radial
head of flexor digitorum superficialis and flexor pollicis longus, and
usually leaves the artery 7 cm proximal to the wrist and passes deep to The posterior cutaneous nerve of the forearm passes along the dorsum
the tendon of brachioradialis. It curves round the lateral side of the of the forearm to the wrist (see Figs 48.34, 49.31, 49.32). It supplies
radius as it descends, pierces the deep fascia and divides into five, the central forearm skin along its course and, near its end, joins the
sometimes four, dorsal digital nerves. On the dorsum of the hand, it dorsal branches of the lateral cutaneous nerve of the forearm.


Elbow and forearm
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The cross-sectional area of the cubital tunnel has been shown to
narrow by almost 55% in full flexion. Ultrasound studies have sug-
gested that the ratio of the cross-sectional area of radial nerve:cubital
tunnel is most strongly linked to reduced conduction velocity (Yoon
et al 2007). Combining elbow flexion with direct pressure over the
cubital tunnel for 60 seconds will elicit symptoms in most affected
patients (Novak et al 1994). Other contributory factors are previous
trauma, especially supracondylar and medial epicondyle fractures in
childhood, valgus instability of the elbow in athletes involved in throw-
ing sports, and degenerative disease.
The most reliable treatment for patients who fail to respond to non-
surgical remedies is a simple release of cubital tunnel. The release
should be complete; care should be taken to avoid damage to branches
of the medial cutaneous nerve of the forearm that usually cross the line
of incision approximately 2 cm above the medial epicondyle and a
mean 3.1 cm distal to the medial epicondyle in all patients (Lowe et al
2004). The nerve should not be circumferentially denuded of its reti-
naculum because this contains its intrinsic blood supply. Transposition
of the nerve should be reserved for cases of persistent snapping or of
failure of a simple release to achieve symptomatic relief. This is rela-
tively unusual and is said to occur in only 7% of cases.
The ulnar nerve is a mixed nerve and so patients may present with
sensory or motor symptoms or a combination of the two, sometimes
with additional physical signs of autonomic disturbance. There may be
tenderness and a positive Tinel’s sign over the nerve at the point of
compression. Numbness and paraesthesiae occur early, followed, in
more severe cases, by weakness of power grip and, ultimately, atrophy
of the lumbricals and interossei with clawing of ring and little fingers.
Patients present with one of two syndromes: the radial tunnel syn-
drome, in which the presentation is that of pain along the lateral border
of the elbow and upper forearm (Roles and Maudsley 1972), or the


posterior interosseous nerve syndrome, which presents with motor
weakness in the distribution of the nerve particularly affecting the
extensors digitorum and extensor carpi ulnaris muscles. Primary treat-
ment is non-operative and involves the avoidance of activities that cause
pain, aided by appropriate splintage. In resistant cases, surgical decom-
pression may be necessary. A complete release of all potential areas of
compression is essential.


anatomical considerations in common forearm and elbow injuries
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Nerve injuries at the elbow
Bonus e-book images
Available with the Gray’s Anatomy e-book
Fig. 49.28 The posterior aspect of the left elbow: superficial
structures.
Fig. 49.33 A type 1 Monteggia fracture with anterior dislocation of
ANATOMICAL CONSIDERATIONS IN COMMON
the radial head.
FOREARM AND ELBOW INJURIES
Fig. 49.34 A Galeazzi fracture-dislocation.
Available with the Gray’s Anatomy e-book Fig. 49.35 Elbow dislocation.


Elbow and forearm
861.e1
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The elbow is a notorious site for nerve injuries, especially in children.
The close proximity of all the major nerve trunks to bone makes them
vulnerable. The ulnar nerve is particularly at risk in elbow dislocation,
especially when the medial epicondyle is displaced into the joint. All
three nerves are at risk of displacement into a dislocated joint. The
posterior interosseous and radial nerves are particularly at risk from a
Monteggia fracture-dislocation. Any nerve may become entrapped
within a fracture, e.g. the median nerve is often accompanied by the
brachial artery in cases of supracondylar fracture. Pain that persists, or
worsens, after reduction of a fracture suggests impending critical ischae-
mia, continuing irritation of the nerve, or both. The nerves are at risk
during operations or other medical interventions, particularly so when
normal anatomical planes are distorted by haematoma, fibrosis or bone
fragments.
Fractures of the shaft of the radius and ulna are commonly displaced,
reflecting not only the violence required to cause such injury but also
the pull of the forearm muscles that may accentuate displacement of
the fracture fragments. Open fractures or penetrating injuries to the
forearm may be associated with nerve and vessel injury. Compartment
syndrome can occur. Monitoring of compartment pressures and careful
neurological examination are required.
Fracture-dislocations of the forearm
Monteggia, Galeazzi and Essex–Lopresti injuries are common combina-
tions of high-energy forearm fractures associated with accompanying
soft tissue injury.
monteggia fracture-dislocation
A Monteggia fracture-dislocation injury is a fracture of the proximal
Fig. 49.33 A type 1 Monteggia fracture with anterior dislocation of the
ulna with dislocation of the radial head; the interosseous membrane
radial head (arrow).
and the triangular fibrocartilage complex remain largely intact, which
means that anatomical reduction of the ulnar fracture will usually
restore congruity of the radiocapitellar and proximal radio-ulnar joints.
The most common type of Monteggia fracture, type 1 (anterior disloca-
tion), occurs when falling on to an outstretched arm hyperextends the


elbow (Fig. 49.33). The forearm is in neutral to mid-pronation, biceps
brachii resists the hyperextension, the anular and quadrate ligaments
rupture under the bending force, and the radial head dislocates. Com-
pressive load then transfers to the ulnar diaphysis, which fails in tension
in an oblique fracture. Type II (posterior dislocation) involves longitu-
dinal force directed up the forearm with the elbow in a flexed position.
The ulnar cortex fails first before rupture of the ulnar collateral ligament
complex and posterior dislocation of the radial head. Four subtypes of
this injury pattern have been identified, based on the location and force
direction through the ulnar fracture (Jupiter et al 1991). Type III Mon-
teggia injuries result in lateral or anterolateral dislocation of the radial
head, associated with a metaphysial fracture of the proximal ulna. Type
IV Monteggia injuries result in an anterior dislocation of the radial head
and a fracture through the proximal third of both the radius and the
ulna. The mechanism of injury is similar to that seen in type I injuries
but the anteriorly directed force of the distal ulnar fragment, combined
with the biceps resistance force, causes a fracture through the proximal
radius (Waters 2010).
Galeazzi fracture-dislocation
A Galeazzi injury is a fracture at the junction of the middle and distal
thirds of the radius, associated with disruption of the distal radio-ulnar
joint (Fig. 49.34). The injury occurs when the forearm is axially loaded
and fully pronated. The radius fractures first, force transmission contin-
ues along the interosseous membrane to the distal ulna, the triangular
fibrocartilage complex is disrupted and the ulnar head dislocates. The
ulnar styloid can also be fractured in this injury (Galeazzi 1934).
Essex–Lopresti injury
Essex–Lopresti injury is a radio-ulnar dissociation injury, usually caused
by a fall on to an outstretched hand that involves a fracture of the radial
head, force transmission between the radius and ulna, and disruption
of the interosseous membrane and the distal radio-ulnar joint. The


radius migrates proximally relative to the ulna (Chow and Leung 2010).
Fig. 49.34 A Galeazzi fracture-dislocation.


Elbow and forEarm
861.e2
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noITCES
Traumatic elbow instability
Posterolateral rotatory pattern instability and dislocation of the elbow,
with or without associated fracture of the radial head and coronoid, are
the three general patterns of traumatic elbow instability (Ring 2010).
Posterolateral rotatory pattern instability is an injury of the capsule and
ligaments that progresses from lateral to medial with a posterolateral
rotatory mechanism (O’Driscoll et al 1992). It usually occurs as the
result of a fall on to an outstretched hand that creates a valgus, axial
posterolateral rotatory force. The ulna and forearm supinate away from
the distal humerus and a posterior dislocation of the elbow occurs (Fig.
49.35). As the elbow dislocates posteriorly, the radial head and coro-
noid impact on the distal humerus, where either can fracture; the ante-
rior band of the ulnar collateral ligament is the last structure to be
disrupted. Varus posteromedial rotational pattern instability and anter-
omedial coronoid facet fractures occur when a fall on to an outstretched
hand produces a varus, axial posteromedial force through the elbow.
The anteromedial facet of the coronoid is fractured and the lateral liga-
ment complex may be injured or the olecranon may be fractured.
Anterior olecranon fracture-dislocations occur as a result of direct vio-
lence to the flexed elbow. The mechanism of posterior olecranon frac- Fig. 49.35 Elbow dislocation.
ture dislocation is less certain; it occurs more commonly in osteopaenic
bone.


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CHAPTER
50
Wrist and hand
In the palm, a curved radial longitudinal line bounds the thenar
SKIN AND SOFT TISSUES
eminence, ending close to the distal wrist crease. Proximal and distal
transverse lines ascend medially across the palm. The proximal line
SKIN begins at the distal end of the thenar crease and runs obliquely to the
middle of the hypothenar eminence across the shafts of the metacar-
Dorsal skin versus palmar skin pals. The distal line begins at or near the cleft between the index and
middle finger, and curves across the palm over the second to fourth
The dorsal skin is thin, mobile and frequently hirsute over the proximal metacarpal heads, near the proximal ends of the fibrous flexor sheaths.
phalanges and the ulnar aspect of the dorsum of the hand. The skin of The second to fifth digits show proximal, middle and distal sets of
the palm and the palmar surface of the digits is thick and hairless, and transverse lines. The proximal, often double, lies approximately 2 cm
has a well-defined stratum lucidum and a higher density of nerve distal to the metacarpophalangeal joints. The middle creases are usually
endings and eccrine sweat glands, but no sebaceous glands. double, the proximal line lying directly over the proximal interphalan-
geal joint. The distal lines are usually single, and lie proximal to the
Skin creases and fingerprints distal interphalangeal joints. The metacarpophalangeal joint of the
thumb is crossed by a crease that starts on the radial side and ends in
the web space level with the base of the proximal phalanx. There is a
Flexure lines crease the skin of the flexor surfaces of the wrist and hand
second, shorter, crease, usually 1 cm distal to this line. Two creases cross
(Fig. 50.1) where they are anchored to the deep fascia. Less regular,
the interphalangeal joint of the thumb (see Fig. 50.1).
mainly transverse, creases cross the dorsal aspect of the radiocarpal,
carpal, metacarpophalangeal and interphalangeal joints. The dorsal
Cutaneous vascular supply
creases are more prominent in extension; the loose skin becomes


stretched in flexion. (For a general review of ‘skin lines’, see p. 156.)
Three anterior transverse lines cross the wrist. The proximal line The skin of the palmar aspect of the wrist is supplied by branches from
marks the proximal limit of the flexor synovial sheaths, the intermediate the superficial palmar branch of the radial artery, the ulnar artery and,
line overlies the radiocarpal joint, and a distal line marks the proximal occasionally, the median artery (see Fig. 46.3). The skin over the thenar
border of the flexor retinaculum. eminence is supplied by small perforating branches from the superficial
palmar branch of the radial artery and the princeps pollicis. The skin
over the hypothenar eminence is supplied by perforating branches from
the ulnar artery, some of which pass through palmaris brevis. The
remainder of the palm is supplied by branches from the common
palmar digital arteries that pierce the palmar aponeurosis, and branches
from the radialis indicis artery. The palmar digital skin is supplied by
branches from each digital artery. In the distal phalanx, the two digital
arteries typically form an H-shaped anastomosis, from which cutaneous
perforators fan out within the pulp. Deep digital veins accompanying
the digital arteries are usually very small and frequently absent. Super-
ficial palmar veins tend to pass dorsally and drain into the larger super-
Distal ficial dorsal venous system.
digital The dorsal skin of the wrist is supplied by branches from an arterial
Superficial
crease plexus that lies over the extensor retinaculum, formed by branches of
palmar arch
Middle the radial artery, including its dorsal carpal branch, the dorsal carpal
Proximal digital branch of the ulnar artery, and anterior and posterior interosseous arter-
transverse crease crease
ies. The blood supply to the dorsum of the hand arises from longitu-
Proximal dinal rows of four or five branches from each of the dorsal metacarpal
digital
arteries, which usually arise either directly from the radial artery or from
crease
the dorsal carpal arch. At the level of the neck of the metacarpals, where
Ulnar
the second, third and fourth dorsal metacarpal arteries communicate


longitudinal
crease with branches from the corresponding common palmar digital arteries,
a large cutaneous perforating branch passes proximally to supply an
Distal
transverse area of skin as far as the dorsal aspect of the wrist.
Intermediate crease The blood supply to the dorsum of the fingers arises proximally from
longitudinal crease the terminal branches of the dorsal metacarpal arteries, (supplying a
region as far distally as the proximal interphalangeal joint) as well as
Deep palmar arch from dorsal branches of the palmar digital arteries that are given off at
each phalangeal level. At the level of the distal phalanx, the cutaneous
Radial longitudinal Distal
crease wrist supply comes from three dorsal arcades: a superficial arcade over the
base of the distal phalanx, and two distal subungual arcades. The skin
crease
of the dorsum of the thumb is supplied by longitudinal axial branches
Proximal of the princeps pollicis and dorsal branches from the palmar digital
wrist arteries.
crease
Degloving injuries of the hand and wrist
Fig. 50.1 The relation of the skin flexure lines and palmar arterial arches
to the bones of the left hand. (Adapted from Drake RL, Vogl AW, Mitchell
Available with the Gray’s Anatomy e-book
A (eds), Gray’s Anatomy for Students, 2nd ed, Elsevier, Churchill
862 Livingstone. Copyright 2010.)


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A degloving injury is one in which the skin is avulsed from its underly-
ing structures, and usually occurs as the result of a low-velocity injury
such as a ring avulsion or when the hand is caught in industrial machin-
ery, typically between rollers or in a conveyor belt. The plane of cleavage
is through the subcutaneous tissues, leaving the underlying structures
essentially intact. The degloving may be complete or partial; complete
avulsion is rare, whereas avulsion of the skin of all or part of the finger
is relatively common.
Urbaniak et al (1981) grouped ring avulsion injuries into three
classes: those in which the blood supply is intact (class I); those in
which the blood supply is compromised (class II); and those in which
digits are either completely degloved or amputated (class III). While
these represent an increasing injury, the avulsion force required to
achieve them does not occur in a linear manner (Kupfer et al 1999).
The longitudinal force applied to a finger causes a traction injury to the
blood vessels, which may extend over a considerable distance. The
crushing element of a degloving injury may cause skin necrosis and
thrombosis of the underlying vessels (Brooks et al 2007).
Treatment of these injuries depends on their extent (Krishnamoorthy
and Karthikeyan 2011). In the acute phase, replantation is the best
option in cases where the skin has been completely separated from the
body. Where the skin remains attached but is devascularized, revascu-
larization by microvascular anastomoses is preferred. If neither of these
procedures is feasible, the avulsed skin may be defatted and reapplied
to the affected part, where it is effectively acting as a split skin graft. If
none of these techniques is practicable, primary amputation may be
considered. Subsequently, reconstruction may be by split skin graft,
skin/fasciocutaneous flap or free flap.


Skin and soft tissues
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A B Fig. 50.2 The approximate area of sensory loss or disturbance after
complete interruption of the radial nerve. A, Anterior. B, Posterior. The
area of sensory disturbance after high lesions is very variable.
Above origin of posterior
cutaneous nerve of arm
and forearm
Below origin of posterior
cutaneous nerve of
arm and forearm
A B Fig. 50.3 The approximate area of sensory loss or disturbance after
complete interruption of the median nerve. A, Anterior. B, Posterior.
Median nerve above palmar
cutaneous branch
Median nerve below palmar
cutaneous branch
A B Fig. 50.4 The approximate area of sensory loss or disturbance
after complete interruption of the ulnar nerve. A, Anterior.
B, Posterior.
Above the level of the dorsal
cutaneous branch
Above the palmar branch
Below the palmar branch Below the origin of the dorsal
cutaneous branch
Basic skin flaps in reconstruction and hand, and the dorsal aspect of the ulnar one and a half digits as
far distally as the nail beds, arises from the dorsal branch of the ulnar
nerve, again ending as dorsal digital nerves. The skin of the dorsum of
Available with the Gray’s Anatomy e-book
the middle and distal phalanges is also supplied by dorsal branches of
the palmar digital nerves.
Cutaneous innervation
NAIL APPARATUS
The skin of the anterior aspect of the wrist is innervated by the terminal
branches of the lateral and medial cutaneous nerves of the forearm. The
skin of the palm is innervated by the palmar branches of the ulnar and The nail apparatus consists of the nail plate, proximal and lateral
median nerves (see Fig. 50.40). The palmar skin of the thumb, index nail folds, nail matrix, nail bed and hyponychium; it is described on
and middle fingers and the radial aspect of the ring finger is supplied page 151; see also Figure 7.18.
by the median nerve, while that of the little finger and ulnar side of the
ring finger is supplied by the ulnar nerve (Figs 50.3, 50.4).
SOFT TISSUES
The cutaneous innervation of the radial aspect of the dorsum of the


wrist and hand, as well as the dorsal aspect of the radial three and a
Flexor retinaculum
half digits as far distally as the nail beds, arises from the terminal
branches of the radial nerve, namely: the dorsal digital nerves (Fig.
50.2). Between two and five dorsal digital nerves supply each digit. The The flexor retinaculum is a strong, fibrous band (see Figs 50.5, 50.25B).
cutaneous innervation of the ulnar aspect of the dorsum of the wrist It crosses the front of the carpus and converts its anterior concavity into


Wrist and hand
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The pedicled groin flap used to be regarded as the workhorse flap for
reconstruction of the hand. This has gradually been replaced by the use
of regional flaps based on the radial or posterior interosseous artery and
by free flaps. Both radial and ulnar forearm flaps have been used to
achieve soft tissue cover of the hand. As they rely on the sacrifice of one
of the major arteries to the hand, it is essential, before considering one
of these procedures, to demonstrate, using flow studies and angio-
graphy, that the remaining vessel, whether radial or ulnar, is adequate.
The radial forearm flap was originally described by surgeons from
the Shenyang Military Hospital in 1978 and was consequently known
as the ‘Chinese flap’. It can be used as a free flap and also as a reversed
pedicled fasciocutaneous island flap to cover soft tissue defects of the
ipsilateral hand. Its blood supply is based on septocutaneous perfora-
tors that arise from the distal part of the radial artery and which supply
the skin on the radial side of the lower forearm; these tend to become
more sparse proximally. Venous drainage is by the venae comitantes
and superficial subcutaneous veins. The ulnar forearm flap is a fascio-
cutaneous flap based on the ulnar artery distal to its common interos-
seous branch. A variant on this flap based on the ascending branch of
the dorsal ulnar artery was described by Becker and Gilbert (1988). It
has the disadvantage of a short pedicle but is useful for achieving cover
of defects of the proximal and ulnar side of the palm.
The posterior interosseous island flap, distally based on the dorsal
carpal arterial arch via the anastomoses between the posterior and
anterior interosseous arteries just lateral to the head of the ulna (Costa
et al 2007), was introduced by Zancolli in 1985. Its principal advan-
tages are that it spares both of the major arteries of the forearm and is
a good match for the skin colour and texture of the dorsum of the hand.
Care must be taken to avoid injury to the adjacent posterior interos-


seous nerve when harvesting the flap. Doppler studies should be carried
out preoperatively to ensure the presence and positioning of the anas-
tomoses between the posterior and anterior interosseous arteries. It has
been claimed that most defects of the hand can be treated using this
flap; its particular advantage is in the treatment of hand injuries with
severe accompanying vascular damage.
The anatomical distribution of the first dorsal metacarpal artery
allows a flap of skin over the dorsum of the proximal phalanx of the
index finger to be raised on the artery and its accompanying venae
comitantes. This flap is particularly useful under certain circumstances
for reconstruction of the thumb following injury.
The distribution of the second, third and fourth dorsal metacarpal
arteries permits the surgical elevation of flaps of dorsal skin based either
proximally, on the dorsal metacarpal arteries proper, or distally, on their
direct cutaneous branches. These flaps may be used for reconstructing
areas of missing tissue elsewhere in the hand.
The dorsal cutaneous branch of the ulnar artery is constant and can
support a flap of skin on the medial aspect of the distal forearm just
proximal to the wrist; it is useful in the reconstruction of areas of
missing skin in this region.


WRiST And HAnd
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nOiTCES
the carpal tunnel that transmits the flexor tendons of the digits and the Extensor retinaculum
median nerve. The retinaculum is short and broad, measuring 2.5–3 cm
both transversely and proximodistally. It is attached medially to the
The extensor retinaculum is a strong, fibrous band that extends obliquely
pisiform and the hook of the hamate. Laterally, it splits into superficial
across the back of the wrist (Fig. 50.6). It is attached laterally to the
and deep laminae. The superficial lamina is attached to the tubercles of
anterior border of the radius, medially to the triquetral and pisiform
the scaphoid and trapezium. The deep lamina is attached to the medial
bones, and, in passing across the wrist, to the ridges on the dorsal aspect
lip of the groove on the trapezium. Together with this groove, the two
of the distal end of the radius. It prevents bowstringing of the tendons
laminae form a tunnel, lined by a synovial sheath, which contains the
across the wrist joint.
tendon of flexor carpi radialis. The retinaculum is crossed superficially
by the ulnar vessels and nerve, immediately radial to the pisiform, and
Palmar fascial complex
by the palmar cutaneous branches of the median and ulnar nerves
(see Fig. 50.40A). A slender band of fascia, the superficial part of the
flexor retinaculum, bridges the ulnar neurovascular bundle and attaches The palmar fascia is a three-dimensional ligamentous system composed
to the radial side of the pisiform, forming a tunnel (Guyon’s canal) that of longitudinal, transverse and vertical fibres (Fig. 50.7).
is an occasional site of ulnar nerve entrapment. The tendons of palmaris
Longitudinal fibre system
longus and flexor carpi ulnaris are partly attached to the anterior surface
of the retinaculum. Distally, some of the intrinsic muscles of the thumb The longitudinal fibres run distally from the tendon of palmaris longus


and little finger are attached to the retinaculum. or the flexor retinaculum of the wrist to fan out across the whole width
of the central third of the palm, producing four well-defined longitudi-
Guyon’s canal Guyon’s canal is a fibro-osseous canal, approximately nal bundles to the index, middle, ring and little fingers. A less well-
4 cm long in the adult, on the anteromedial side of the wrist (Fig. 50.5). defined bundle passes to the thumb. Distal to the transverse fibres of
The roof is formed by the palmar carpal ligament and palmaris brevis. the palmar aponeurosis, the longitudinal fibres pass in three layers
The floor is formed by the transverse carpal and pisohamate ligaments (McGrouther 1982). The most superficial longitudinal fibres (layer 1)
and, more distally, by the pisometacarpal ligaments and flexor digiti are inserted superficially into the skin of the distal palm between the
minimi. The ulnar side is bounded by flexor carpi ulnaris, the pisiform distal palmar crease and the proximal digital crease. Some superficial
bone and abductor digiti minimi, and the medial side is bounded by fibres pass distally into the palmar midline of the digit. Deeper longi-
the extrinsic flexor tendons, the transverse carpal ligament and the hook tudinal fibres (layer 2) pass deep to the natatory ligament and neuro-
of the hamate. The fibrous arcade at the origin of the hypothenar vascular bundles into the skin at the apex of the web space and into the
muscles lies distally. fingers themselves, where they are continuous with Cleland’s ligaments
The canal transmits the ulnar nerve and artery, together with occa- and the lateral digital sheet. Deeper still, the longitudinal fibres in layer
sional venae comitantes. The ulnar nerve divides within it at the level 3 perforate the deep transverse metacarpal ligament to pass around the
of the hook of the hamate into a deep, radial motor branch and a sides of the metacarpophalangeal joint and attach to the metacarpal


superficial, ulnar sensory branch. If the nerve is compressed proximally, bone and proximal phalanx, and extensor tendon.
both modalities will be affected, whereas, distal to the bifurcation, only
the sensory or motor branch will be compromised. Variations in the Transverse fibre system
branching of the ulnar nerve may occur. The transverse fibre system consists of the superficial transverse meta-
The most common variant involves the formation of abductor digiti carpal (natatory) ligament, the transverse fibres of the palmar aponeur-
minimi, particularly when an accessory head is present. osis and the deep transverse metacarpal ligament.
Tendons of extensor digitorum Fig. 50.6 The synovial sheaths of the tendons
on the extensor aspect of the left wrist. (With
permission from Waschke J, Paulsen F (eds),
Sobotta Atlas of Human Anatomy, 15th ed,
Elsevier, Urban & Fischer. Copyright 2013.)
First dorsal interosseous
Intertendinous connections
Extensor pollicis brevis
Synovial sheath of
extensor digiti minimi
Abductor pollicis longus
Synovial sheaths of
abductor pollicis longus and
extensor pollicis brevis
Synovial sheath of
extensor carpi ulnaris
Extensor retinaculm
Synovial sheaths of
extensor digitorum
and extensor indicis
Synovial sheath of
extensor pollicis longus
Synovial sheaths of extensores carpi radiales


Wrist and hand
864.e1
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Flexor retinaculum Hook of hamate Ulnar nerve (superficial branch)
Ligamentous
band
Ulnar nerve
(deep branch)
Pisohamate ligament
Pisiform synovial
sheaths (green)
Volar carpal ligament
Palmaris longus
Flexor carpi ulnaris
Ulnar artery
Ulnar nerve
Fig. 50.5 Guyon’s canal (space) at the wrist. Note the possibilities of
entrapment at, and distal to, the volar carpal ligament. (Courtesy of Rolfe
Birch, all rights reserved, published in Birch R, Surgical Disorders of the
Peripheral Nerve. 2nd edition, 2011. Springer-Verlag, London.)


Skin and soft tissues
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A Natatory ligament B
Transverse fibres of
palmar aponeurosis
Digital artery
Proximal commissural ligament Digital nerve
Natatory ligament
Palmaris brevis
Transverse fibres of
palmar aponeurosis
Longitudinal fibres of
palmar aponeurosis
Distal commissural ligament
Longitudinal fibres of palmar aponeurosis
Transverse retinacular
D E ligament
Lateral digital sheet
C
Cleland's ligament
Grayson's ligament
Cleland's ligament
Layer 1 skin attachment fibres
Cleland's ligament
Layer 2
Layer 3 Natatory ligament
Vertical septum Skin
Spiral band
Extensor tendon Grayson's ligament
Transverse fibres
Pretendinous fibres Pretendinous band Digital artery
Digital nerve
Cleland's ligament
Fig. 50.7 The palmar aponeurosis and distal fascial complex. A, The palmar fascia. B, Structures at the web space. C, The fate of the distal longitudinal
fibres. D–E, The normal digital fascia.
Superficial transverse metacarpal ligament aponeurosis to the underlying deep transverse metacarpal ligament,
(natatory ligament) forming compartments that contain the flexor tendons and the lumbri-
cals and neurovascular bundles.
The fibres of the superficial transverse metacarpal ligament cross the
apex of the web skin and extend into each digit to blend with the lateral
digital sheet. They limit the separation of adjacent fingers and form the Digital fascial complex
distal commissural ligament in the web space of the thumb.
The superficial fascia within a finger is fibrofatty in the palmar and
Transverse fibres of the palmar aponeurosis
dorsal aspects, but condenses laterally into the lateral digital sheet (see
The transverse fibres of the palmar aponeurosis represent the deepest Fig. 50.7). The flexor sheath represents a well-defined thickening of the
layer of the palmar fascia. They lie proximal to the distal palmar crease fascia and is discussed in detail on page 866. Cleland’s ligaments extend
in a band approximately 2 cm wide, interconnecting the anterior fibres from the sides of the phalanges, pass dorsal to the neurovascular


of the flexor tendon sheaths with the fasciae over the thenar and bundles, and insert into the lateral digital sheet. Grayson’s ligaments
hypothenar muscles. The extension to the first ray forms the proximal are more delicate, may even be discontinuous, and pass from the lateral
commissural ligament. sides of the phalanges anterior to the neurovascular bundles to insert
into the lateral digital sheet. Landsmeer’s ligaments are inconsistent
deep transverse metacarpal ligament
anatomical structures made up of transverse and oblique retinacular
The strong fibres of the deep transverse metacarpal ligament lie deep to ligaments.
the palmar aponeurosis and flexor sheaths, and are attached to the volar
plates of the metacarpal heads of the fingers.
Functions of the fascia of the hand
Vertical fibre system
The vertical fibres are more delicate. They pass from the dermis, between The fascial continuum of the hand performs a number of different, but
the longitudinal and transverse fibres, to the fibrous flexor sheaths interrelated, functions. It channels and provides a gliding surface for
and the metacarpal bones. They are concentrated on either side of the structures in transit between the forearm and the digits; transmits loads;
palmar skin creases, as well as the thenar and hypothenar eminences. anchors the skin; protects underlying vessels; and provides a framework
A series of vertical septa pass from the transverse fibres of the palmar for muscle attachments.


WRiST And HAnd
866
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nOiTCES
Channelling of structures in transit between nerve (15.5 mm) is seen just proximal to the carpal tunnel; similar
forearm and digits excursion of the ulnar nerve has been recorded as 14.8 mm in cadavers
(Wilgis and Murphy 1986).
The vertical septa act as spacers between the tendons and neurovascular
bundles of the individual digital rays. Where tendons change direction
Vascular protection and pumping action
around a concave surface, the channels are thickened. The septa form
The blood vessels of the palm are surrounded by a cuff of tough
sheaths with specialized pulleys to prevent the tendon springing away
fascia or by a fatty pad. When the hand is compressed, as in gripping,
from the underlying skeleton.
these relatively incompressible fascial structures function as a venous
Transmission of loads pumping mechanism to assist return of blood from the limb. By con-
trast, large capacitance veins on the dorsum of the hand lie in gliding
At points where compressive loading is applied to the hand, such as the
skin, surrounded by loose areolar tissue, which allows the veins to
finger pulp and palm, loculi of fat act as shock absorbers. The loculi are
dilate.
contained within defined fibrous boundaries, which means that the
shape, but not the volume, of each loculus can change. The compliance Framework for muscle attachments
or deformability of the boundaries determines the amount of shock
Many of the small muscles of the hand, such as abductor pollicis brevis
absorption. Local ‘turgor’ (deformability) and blood volume are meas-
and palmaris longus, are attached to the fascial skeleton, at least in part.
ures of this anatomical property.
The fascial framework can be visualized as a harness by which muscles
The palm also contains much larger fibrous compartments between
can act on the underlying skeleton. The metacarpophalangeal joint is
skin and skeleton that transmit muscles, tendons and other structures.
moved by a ring of fascial and ligamentous structures that surrounds
The honeycomb pattern of these compartments constitutes the palmar
the joint and to which tendons are attached.
shock absorption system. The soft, padded parts of the hand are able


to conform to the contours of objects that are grasped, and this permits Dupuytren’s disease
better interpretation of sensation and better grip.
The hand must also resist tensile loading. Tendons and ligaments
Available with the Gray’s Anatomy e-book
are particularly suitable for resisting such forces but many other parts
of the fascial continuum, such as the anchorage system of the palm,
Digital and palmar spaces
also play a major role in resisting ‘pulling’ forces.
Anchorage There are many potential spaces within the hand, often with ill-defined
Skin is retained by fascial ligaments that allow the hand to flex while margins. The nail fold is a ‘U-shaped’ space made up of the eponychium
retaining the skin in position. The palmar creases have been described and the lateral nail fold. The apical spaces at the tip of the finger are
as skin ‘joints’. Fascial anchors may be vertical (perpendicular to the formed by the fibrous attachments of the distal phalanx to the tip of
palm), as in the mid-palm, where scattered vertical fibres run from the the digital pulp skin. The digital pulp spaces are confined compartments
dermis down into the depths of the hand; horizontal (in the plane of bounded by the digital creases that overlie the joints, and are attached
the palm); or oblique to the skin surface. to the underlying pulleys. The synovial flexor tendon sheaths are
The insertion of the longitudinal (pretendinous) fibres of the palmar described on page 879. The web space is bounded distally by the skin
aponeurosis is an example of a well-developed horizontal anchorage and natatory ligament, by the deep transverse metacarpal ligament
system. The most superficial longitudinal fibres insert into the dermis posteriorly, and by the deep attachments of the palmar fascia, together
of the distal palm. This arrangement resists horizontal shearing force with their lateral attachments to the tendon sheaths, proximally. The
in gripping tasks, such as holding a hammer, where it prevents distal deep palmar space is a complex, three-dimensional space, limited proxi-
skin slippage or degloving of the palm during use. The characteristic mally by the carpal tunnel. It lies deep to the palmar aponeurosis,


blisters on the palms of those unaccustomed to such use map out the between the radial and ulnar condensations of vertical fibres that
sites of the skin anchorage points. This anchorage system can be dem- connect the palmar aponeurosis to the thenar and hypothenar emi-
onstrated by flexing the palm until the skin of the distal palm folds nences. Partitions that pass deeply from the longitudinal bands of the
loosely. An attempt to pull the loose skin distally will reveal the anchor- palmar aponeurosis form eight narrow compartments; four contain the
ing longitudinal fibres of the palmar aponeurosis. digital flexor tendons and four contain the lumbricals and the neuro-
Oblique anchors occur in the fingers where Cleland’s ligaments vascular bundles.
tether the skin of the proximal and middle segments of the digits to the
region of the proximal interphalangeal joints. Infections of the hand The spaces of the hand limit the spread of
infection. Infections in the digit can occur in the nail fold (paronychia);
Binding
the apical spaces at the very tip of the finger; the distal pulps (a felon);
Transversely orientated fascial structures help to maintain the transverse and the flexor sheaths. The flexor synovial sheath of the thumb and the
arch of the hand by ‘binding’ the underlying skeletal structures or the little finger is continuous throughout the palm. Infection may spread
tendon sheaths. to the palm and into other sheaths within the carpal tunnel but sepsis
is as serious in those digits whose sheaths do not communicate with
Limiting or tethering
the carpal tunnel sheaths (index, middle, ring) as it is in those that do
Joint motion is limited not only by joint ligamentous action, but also, (thumb, little finger). Deep infections in the palm are usually not con-
in some cases, by skin tightness. Skin in the interdigital webs is generally fined to any particular space.
reinforced by fascial ligamentous fibres that run just beneath the
dermis in a direction that resists stretch; they are well developed in the Compartment syndrome of the hand
thumb web.
Available with the Gray’s Anatomy e-book
Lubrication
There are many other gliding planes, e.g. between periosteum and the


extensor apparatus, and between the latter and the skin, on the dorsum
BONES
of the digits. The flexor tendon sheaths are lined by synovium.
Biomechanical studies of tendons gliding within their sheaths have
emphasized the importance of avoiding extreme postures of a joint, The skeleton of the hand consists of the carpus, metacarpus and the
which increase the friction between tendon and pulley, as well as the phalanges.
need to establish a smooth, well-lubricated tendon surface after repair.
Increased friction within a tendon sheath may, in part, explain the cause
of spontaneous rupture of extensor pollicis longus because the gliding CARPUS
resistance of the tendon has been shown to be significantly higher than
that of other tendons (An 2007). Synergistic movements in the post- The carpus contains eight bones: four each in proximal and distal rows
repair phase of recovery have been shown to improve tendon excursion (Figs 50.8–50.9). In radial to ulnar order, the scaphoid, lunate, tri-
and postoperative function. quetrum and pisiform make up the proximal row, and the trapezium,
Within the carpal tunnel and hand, the median nerve has been trapezoid, capitate and hamate make up the distal row. The pisiform
shown to glide by up to 3 mm, depending on the position of the articulates with the palmar surface of the triquetrum. The other three
elbow and the attitude of the forearm in pronation or supination proximal bones form an arch that is convex proximally, and which
(Echigo et al 2008). The greatest longitudinal excursion of the median articulates with the radius and articular disc of the distal radio-ulnar


Wrist and hand
866.e1
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Dupuytren’s disease appears to be inherited as an autosomal dominant An abscess in any of the digital or palmar spaces should always be
trait with incomplete penetrance (MacFarlane 1991, Ling 1963). It has drained. Incisions should, wherever possible, follow the line of the
been associated with heavy alcohol consumption, smoking, diabetes, flexion creases and adhere to the principles of extensile exposure. The
manual work and vibration exposure, and possibly the ingestion of motor and palmar cutaneous branches of the median nerve are poten-
anticonvulsants (Descatha et al 2011). In the proliferative stage of the tially at risk when draining a thenar space abscess through a palmar
disease, there is considerable myofibroblast activity, which may be the incision. A dorsal approach through the first web space, perpendicular
result of upregulation of the musculo-aponeurotic fibrosarcoma onco- to the web itself and between the first and second metacarpals, is to be
gene homologue B (MafB), found in the diseased cord tissue (Lee et al preferred on anatomical grounds but may not always achieve adequate
2006). Mechanical stimuli subsequently cause the alignment of myo- drainage on its own. The mid-palmar space is best approached through
fibroblasts along the lines of traction, which are later replaced by a combination of a transverse distal palmar incision with an oblique
collagen. longitudinal extension (McDonald et al 2011).
The pattern of contracture is determined by the anatomy of the basic Hypothenar space infections are very rare. They tend to be confined
constituents of the palmar and digital fascia. The pretendinous bands by the hypothenar fascia and result in swelling of the ulnar side of the
that constitute the superficial layer of the palmar aponeurosis (layer 1) hand with some flexion and adduction of the little finger. They may be
are most frequently involved. The development of nodules usually drained by an incision along the ulnar border of the space without
precedes cord formation; the nodules tether the skin to the deep fascia. significant risk of damage to underlying structures.
Contracture of the pretendinous cords causes flexion of the metacarpo-


phalangeal joints. The cords run between the flexor sheaths and the There are 10 identifiable compartments in the hand: four contain the
neurovascular bundles. Shortening of the vertical bands (of Grapow) dorsal interossei, three contain the palmar interossei, and three contain
results in the appearance of skin pits and thickening of the skin. Involve- the thenar and hypothenar muscles and adductor pollicis. Any or all of
ment of the natatory ligament restricts abduction of the fingers. None these compartments may be injured by a rise in intracompartmental
of these changes usually displaces the neurovascular bundle because pressure. The absolute pressure at which damage is caused has not been
each component lies superficially in the palm. determined but is thought to be less than that required in the lower
The pretendinous cord in the palm extends into a finger as a central limb. Injury may be caused by blast, burn or crush, and by injection,
cord that lies superficially in the midline. The lateral digital sheet gives whether of therapeutic substances at low pressure or of industrial agents
rise to a lateral cord that is attached to the skin or flexor tendon sheath at high pressure. Symptoms may be as non-specific as aching of the
near Grayson’s ligament, causing a flexion contracture of the proximal hand at rest or on exercise, or the hand may become painful with
interphalangeal joint and, sometimes, displacing the digital neurovas- increasing swelling and loss of movement in the digits. On examina-
cular bundle medially. Spiral cords arise from the pretendinous band tion, an intrinsic minus-type hand (claw hand) may be seen, with
in layer 1 of the palmar fascia and pass deeper through layer 2 to be- extension of the metacarpophalangeal joints and flexion of the proxi-
come attached to the middle phalanx by Grayson’s ligament. They mal interphalangeal joints. Intracompartmental pressure measurements
are so named because they spiral round the neurovascular bundle, should be taken; the means by which this is done is not critical (Ortiz
displacing it proximally, palmarwards and towards the midline as and Berger 1998). Any suspicion of a compartment syndrome should


contracture increases, and rendering it vulnerable to injury during fas- be followed by prompt decompression. It is usually possible to decom-
ciectomy (MacFarlane 1974). The distal interphalangeal joint is uncom- press thoroughly through two dorsal longitudinal incisions over the
monly involved because the palmar aponeurosis only extends as far as second and fourth metacarpals, as well as release of the flexor retinacu-
the sides of the middle phalanx. lum. The dorsal compartments are addressed directly and the volar
compartments opened deep by longitudinal incision. (See also Eardley
and Stewart (2010).)


Bones
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A Metacarpals B
Second Adductor pollicis (transverse head)
Third
Fourth
Fifth Third palmar
interosseous
Second palmar
First interosseous
Fourth palmar
interosseous
Opponens
Opponens digiti minimi
pollicis
Opponens
digiti minimi
Trapezoid Hook of Abductor pollicis
hamate longus Pisometacarpal
ligament
Trapezium Capitate Flexor pollicis brevis, Flexor digiti minimi
superficial head
Abductor digiti minimi
Pisiform
Tubercle of scaphoid Opponens pollicis
Triquetrum Flexor carpi ulnaris
Abductor pollicis brevis
Lunate
Flexor carpi radialis Flexor pollicis brevis, Adductor pollicis,
deep head oblique head
Fig. 50.8 A, The carpal and metacarpal bones of the left hand: palmar aspect. B, Sites of muscle attachments (except the dorsal interossei).
A Metacarpals B
Third Second
Fourth
Fifth
Second dorsal
interosseous
First
Third dorsal
interosseous
Fourth dorsal First dorsal
interosseous interosseous
First palmar
Extensor carpi interosseous
ulnaris
Styloid process
Capitate
Trapezium
Hamate Extensor carpi
Trapezoid
radialis longus
Triquetrum
Scaphoid Extensor carpi
Lunate radialis brevis
Articulate with radius
Fig. 50.9 A, The carpal and metacarpal bones of the left hand: dorsal aspect. B, Sites of muscle attachments.
joint. The distal concavity of the arch articulates with the capitate and border of the palmar thenar eminence, radial to the tendon of flexor
hamate. carpi radialis. The tubercle of the trapezium is a vertically rounded ridge
The dorsal carpal surface is convex. The palmar surface forms a on the anterior surface of the bone, slightly hollow medially and just


deeply concave carpal groove, accentuated by the palmar projection of distal and radial to the scaphoid tubercle; it is difficult to palpate. Both
the radial and ulnar borders. The ulnar projection is formed by the the scaphoid and trapezium may be grasped individually, and moved
pisiform and the hook (hamulus) of the hamate. The pisiform is at the passively, by firm pressure between an opposed index finger and thumb
proximal border of the hypothenar eminence, on the ulnar side of the applied to the palmar surface and ‘anatomical snuff-box’ simultane-
palm, and it is easily felt in front of the triquetrum. The hamulus is ously. The carpal groove is made into an osseofibrous carpal tunnel
concave in a radial direction; its tip is palpable 2.5 cm distal to the by the flexor retinaculum attached to its margins. The tunnel carries
pisiform, in line with the radial border of the ring finger. The superficial flexor tendons and the median nerve into the hand. The retinaculum
division of the ulnar nerve can be rolled over it. The radial border of strengthens the carpus and augments flexor efficiency. Radiocarpal,
the carpal groove is formed by the tubercles of the scaphoid and trape- intercarpal and carpometacarpal ligaments are attached to the palmar
zium. The former is distal on the anterior scaphoid surface and palpa- and dorsal surfaces of all of the carpal bones, except the triquetrum and
ble (sometimes, also visible) as a small medial knob at the proximal pisiform.


WRiST And HAnd
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A. Scaphoid B. Lunate
Dorsal rough surface For radius For lunate Tubercle For triquetrum For hamate For radius
For trapezium For trapezoid For capitate For capitate For scaphoid
Dorsal aspect Palmar aspect Distomedial aspect Proximolateral aspect
C. Triquetrum D. Pisiform E. Trapezium
For pisiform For lunate For triquetrum For trapezoid Groove Tubercle Tubercle For 2nd metacarpal
For hamate For 2nd metacarpal For 1st metacarpal For scaphoid For trapezoid
Palmar aspect Proximomedial aspect
F. Trapezoid G. Capitate
Rough area, nonarticular For trapezium For scaphoid Dorsal surface For lunate
Dorsal surface For scaphoid Dorsal surface For hamate
For capitate Palmar surface For 2nd metacarpal For trapezoid For 2nd metacarpal For 4th metacarpal Palmar surface
Proximomedial aspect Distolateral aspect
H. Hamate
Notch for deep branch
Palmar surface Hamulus (hook)
of ulnar nerve
For 5th metacarpal For capitate
For triquetrum For 4th metacarpal
Lateral aspect Medial aspect
Fig. 50.10 Disarticulated carpal bones.
Individual carpal bones its absence, by branches of the superficial palmar artery (Oehmke et al
2009). The middle and distal thirds of the palmar surface are supplied
by the superficial palmar artery and small radial rami arteries. The distal
Scaphoid
third may also receive branches from the first dorsal metacarpal artery.
The scaphoid is the largest element in the proximal carpal row (Fig.
The dorsal surface is principally supplied by the dorsal scaphoid artery
50.10A, see Figs 50.8, 50.9). It has a long axis that is distal, radial and
and by branches of the styloid artery. Variation in this pattern is not
slightly palmar in direction. A round tubercle on the distolateral part


uncommon. Intraosseous blood vessels have been found close to the
of its palmar surface is directed anterolaterally (see Fig. 50.8A), and
articulating surface.
provides an attachment for the flexor retinaculum and abductor pollicis
brevis; it is crossed by the tendon of flexor carpi radialis. The rough Scaphoid bone fractures
dorsal surface is slightly grooved, narrower than the palmar, and pierced
by small nutrient foramina, which are often restricted to the distal half.
Available with the Gray’s Anatomy e-book
The radial collateral ligament is attached to the lateral surface, which is
also narrow and rough. The remaining 42% of surfaces are all articular.
Lunate
The radial (proximal) surface is convex, proximal and directed proximo-
laterally; the lunate surface is flat and semilunar, and faces medially; The lunate is approximately semilunar and articulates between the
the capitate surface is large, concave, distal, and directed distomedially. scaphoid and triquetrum in the proximal carpal row (see Figs 50.8–
The surface for the trapezium and trapezoid is continuous, convex 50.10B). Its rough palmar surface, almost triangular, is larger and wider
and distal. than the rough dorsal surface. Its smooth convex proximal surface
The proximal, palmar surface of the non-articulating portion of the articulates with the radius and the articular disc of the distal radio-ulnar
scaphoid is supplied by branches from the palmar carpal artery or, in joint. Its narrow lateral surface bears a flat semilunar facet for the


Wrist and hand
868.e1
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RETPAHC
Gelberman and Menon (1980) describe the proximal 70–80% of the
scaphoid as being supplied by branches of the radial artery that enter
along its dorsal ridge, either just distal to the waist (14%), directly over
the waist (59%) or just proximal to the waist (27%). They estimated
that 14% of their specimens would have had significant interruption
and 59% a partial interruption to the vascularity of the proximal pole
of the scaphoid from a fracture through the waist, and that failure to
unite would have resulted in avascular necrosis of the proximal frag-
ment. It has been argued that an inadequate blood supply is unlikely
to be the cause of scaphoid non-union after fracture (Oehmke et al
2009), but see also Sendher and Ladd (2013).
The scaphoid is the most frequently fractured carpal bone, typically as
a result of a fall on to the outstretched hand. Compson (1998), in a
study of the true, rather than the radiological, anatomy of scaphoid
fractures, identified three distinct fracture patterns: transverse through
the ‘surgical waist’; oblique (45° to the surgical waist) in the plane of
the dorsal sulcus; and through the proximal pole.


Bones
869
05
RETPAHC
scaphoid. The medial surface, almost square, articulates with the tri- a large facet for articulation with the hamate, which is deeper proxi-
quetrum and is separated from the distal surface by a curved ridge, mally where it is partly non-articular. Palmar and dorsal surfaces are
usually somewhat concave for articulation with the edge of the hamate roughened for carpal ligaments, the dorsal being the larger.
in adduction (see Fig. 50.10B, left). The distal surface is deeply concave
Hamate
to fit the medial part of the head of the capitate.
The hamate is cuneiform and bears an unciform hamulus (hook) that
Kienböck’s disease projects from the distal part of its rough palmar surface (see Fig.
50.10H). The hamulus is curved with a lateral concavity and its tip
Available with the Gray’s Anatomy e-book inclines laterally, contributing to the medial wall of the carpal tunnel
(see Figs 50.8–50.9). The flexor retinaculum is attached to the apex of
Triquetrum the hamulus. Distally, on the hamular base, a slight transverse groove
may be in contact with the terminal deep branch of the ulnar nerve.
The triquetrum is somewhat pyramidal and bears an oval isolated facet
The remaining palmar surface, like the dorsal, is roughened for attach-
for articulation with the pisiform on its distal palmar surface (see Figs
ment of ligaments. A faint ridge divides the distal surface into a smaller
50.8–50.10C). Its medial and dorsal surfaces are confluent, and marked
lateral facet that articulates with the base of the fourth metacarpal, and
distally by the attachment of the ulnar collateral ligament, but smooth
a medial facet for articulation with the base of the fifth. The proximal
proximally to receive the articular disc of the distal radio-ulnar joint
surface, the thin margin of the wedge, usually bears a narrow facet that
in full adduction. The hamate surface, lateral and distal, is concavo-
contacts the lunate in adduction. The medial surface is a broad strip,
convex, broad proximally and narrow distally. The lunate surface,


convex proximally, concave distally, which articulates with the tri-
almost square, is proximal and lateral.
quetrum; distally, a narrow medial strip is non-articular. The lateral
surface articulates with the capitate by a facet covering all but its distal
Pisiform
palmar angle.
The pisiform is a sesamoid bone and is shaped like a pea, with a disto-
lateral long axis (see Figs 50.8, 50.10D). It bears a dorsal flat articular Ossification
facet for the triquetrum. The tendon of flexor carpi ulnaris and the distal
continuations of the tendon, the pisometacarpal and pisohamate liga-
Carpal bones are cartilaginous at birth, although ossification may have
ments, are all attached to the palmar non-articular area, which sur-
started in the capitate and hamate. Each carpal bone is ossified from
rounds and projects distal to the articular surface.
one centre – capitate first and pisiform last; the order in the others varies
(Figs 50.11–50.15). The capitate begins to ossify in the second month;
Trapezium
the hamate at the end of the third month; the triquetrum in the third
The trapezium has a tubercle and groove on its rough palmar surface year; and the lunate, scaphoid, trapezium and trapezoid in the fourth
(see Figs 50.8A, 50.10E). The groove, which is medial, contains the year in females and fifth year in males. The pisiform begins to ossify in
tendon of flexor carpi radialis, and two layers of the flexor retinaculum the ninth or tenth year in females, and the twelfth in males. The order
are attached to its margins. The tubercle is obscured by the thenar varies according to sex, nutrition and, possibly, race. Occasionally, an
muscles that are attached to it (opponens pollicis, flexor pollicis brevis os centrale occurs between the scaphoid, trapezoid and capitate bones;


and abductor pollicis brevis) (see Fig. 50.8B). The elongated, rough during the second prenatal month, it is a cartilaginous nodule that
dorsal surface is related to the radial artery. The large lateral surface is usually fuses with the scaphoid. Occasionally, lunate and triquetral
rough for attachment of the radial collateral ligament and capsular liga- elements may fuse. Other fusions and accessory ossicles have also been
ment of the thumb carpometacarpal joint. A large sellar surface faces described.
distolaterally and articulates with the base of the first metacarpal. Most
distally, it projects between the bases of the first and second metacarpal
bones and carries a small, quadrilateral, distomedially directed facet METACARPUS
that articulates with the base of the second metacarpal. The large medial
surface is gently concave for articulation with the trapezoid. The proxi- The metacarpus consists of five metacarpal bones, conventionally num-
mal surface is a small, slightly concave facet for articulation with the bered in radio-ulnar order. These are small long bones, with a distal
scaphoid. Its ridge, or ‘summit’, fits the concavity of the first metacarpal head, shaft and expanded base. The rounded heads articulate with the
base, and extends in a palmar and lateral direction, at an angle of proximal phalanges. Their articular surfaces are convex, although less
approximately 60° with the plane of the second and third metacar- so transversely, and extend further on the palmar surfaces, especially at
pals. Abduction and adduction occur in the plane of the ridge, which their margins. The knuckles are produced by the metacarpal heads. The
is shorter than the corresponding metacarpal groove. Their contours metacarpal bases articulate with the distal carpal row and with each
vary reciprocally: they are more curved near the second metacarpal other, except the first and second. The shafts have longitudinally concave
base, whereas the radius of curvature is longer further away from this palmar surfaces, which form hollows for the palmar muscles. Their


site. The two surfaces are not completely congruent, and the area of dorsal surfaces bear a distal triangular area, which is continued proxi-
close contact probably moves towards the palm in adduction and dor- mally as a round ridge. These flat areas are palpable proximal to the
sally in abduction. While the axis of flexion/extension passes through knuckles.
the trapezium, that for adduction/abduction is in the metacarpal The medial four metacarpals gently diverge proximodistally. The first
base. Flexion is accompanied by medial rotation, and extension by metacarpal is more anterior and rotated medially on its axis through
lateral rotation. 90°, so that its morphologically dorsal surface is lateral, its radial
border palmar, its palmar surface medial, and its ulnar border dorsal.
Trapezoid
Hence, the thumb flexes medially across the palm and can be rotated
The trapezoid is small and irregular. It has a rough palmar surface that into opposition with each finger. Opposition depends on medial rota-
is narrower and smaller than its rough dorsal surface (see Figs 50.8– tion and is important in manual dexterity; when an object is grasped,
50.10F). The distal surface, which articulates with the grooved base of fingers and thumb encircle it from opposite sides, greatly increasing the
the second metacarpal, is triangular, convex transversely and concave at power and skill of the grip.
right angles to this. The medial surface articulates by a concave facet
with the distal part of the capitate, the lateral surface articulates with
Individual metacarpal bones
the trapezium, and the proximal surface articulates with the scaphoid.
Capitate First metacarpal
The capitate is the central and largest carpal bone. It articulates with the The first metacarpal is short and thick (see Figs 50.8–50.9; Fig. 50.16A).
base of the third metacarpal via its triangular distal concavo-convex Its dorsal (lateral) surface can be felt to face laterally; its long axis
surface (see Figs 50.8–50.10G). Its lateral border is a concave strip for diverges distolaterally from its neighbour. The shaft is flattened, dorsally


articulation with the medial side of the base of the second metacarpal. broad and transversely convex. The palmar (medial) surface is longitu-
Its dorsomedial angle usually bears a facet for articulation with the base dinally concave and divided by a ridge into a larger lateral (anterior)
of the fourth metacarpal. The head projects into the concavity formed and smaller medial (posterior) part. Opponens pollicis is attached to
by the lunate and scaphoid; the proximal surface articulates with the the radial border and adjoining palmar surface; the first dorsal inter-
lunate, and the lateral surface with the scaphoid. The facets for the osseous muscle (radial head) is attached to its ulnar border and
scaphoid and trapezoid, though usually continuous on the distolateral adjacent palmar surface. The base is concavo-convex and articulates
surface, may be separated by a rough interval. The medial surface bears with the trapezium. Abductor pollicis longus is attached on its lateral


Wrist and hand
869.e1
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RETPAHC
Kienböck’s disease, first described in 1910, is avascular necrosis of the
lunate. Aetiology remains unclear but is thought to be associated with
the arterial blood supply to the lunate. Up to eight small vessels usually
enter both the dorsal and the palmar aspects of the bone, three on the
dorsal surface and five on the palmar; they divide into smaller branches
within the bone. However, in some cadaveric studies, only one vessel
has been identified, and it has been inferred that this pattern would
render an individual at increased risk of osteonecrosis, particularly if
the branching pattern within the bone is limited. Other possible aetio-
logical factors include disruption or obstruction of the venous outflow
from the lunate, causing increased intraosseous pressure; negative ulnar
variance; trauma; variations in the shape of the lunate; and mechanical
factors. The natural history of the disease process is unknown.
While patients generally present with pain and stiffness of the wrist,
these symptoms correlate poorly with the radiological findings and,
indeed, patients may be asymptomatic. (For further reading, see Cross
and Matullo (2014).)


WRiST And HAnd
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nOiTCES
Fig. 50.11 A radiograph Fig. 50.13 A radiograph
of a hand at 21 years of a hand at 11 years
2
(male), dorsopalmar (female), dorsopalmar
projection. Note the projection. Compare
early stages of the maturing
ossification in the ossification with that
epiphyses at the seen in Figures 50.11
proximal ends of the and 50.12. Note the
phalanges and first addition of the pisiform.
metacarpal; the distal
ends of the remaining
metacarpals and radius;
and for the capitate,
hamate and lunate.
Typically, the centre for
the lunate is preceded
by the centre for the
triquetrum. Compare
with Figures 50.12 and
50.13.
Fig. 50.12 A radiograph
of a hand at 61 years
2
(male), dorsopalmar
projection. Note the
more advanced state of 1 14
the centres of
ossification that were
already visible in Figure
50.11, and the
appearance of 2
additional centres in the
distal ulnar epiphysis
3
and in the triquetrum,
scaphoid, trapezium
and trapezoid.
15
4
16
5 17
6 18
7
8
9 19
20
10
21
11 22
12 23
13 24
Fig. 50.14 A radiograph of an adult hand, dorsopalmar projection. Key: 1,
head of middle phalanx of middle finger; 2, head of proximal phalanx of
(palmar) side, the first palmar interosseous muscle to its ulnar side. The ring finger; 3, shaft of proximal phalanx of ring finger; 4, head of fifth
head is less convex than in other metacarpals and is transversely broad. metacarpal; 5, shaft of fifth metacarpal; 6, base of fifth metacarpal; 7,


Sesamoid bones glide on radial and ulnar articular eminences on its hook of hamate; 8, triquetrum; 9, hamate; 10, pisiform; 11, styloid
palmar aspect. process of ulna; 12, lunate; 13, head of ulna; 14, distal phalanx of index
finger; 15, distal phalanx of thumb; 16, proximal phalanx of thumb; 17,
Second metacarpal
sesamoid bone; 18, trapezoid; 19, trapezium; 20, capitate; 21, scaphoid;
The second metacarpal has the longest shaft and largest base (see Figs 22, styloid process of radius; 23, distal radio-ulnar joint; 24, radius.
50.8–50.9; Fig. 50.16B). The latter is grooved in a dorsopalmar direc-
tion for articulation with the trapezoid. Medial to the groove, a deep
ridge articulates with the capitate; laterally, nearer the dorsal surface of of the second palmar interosseous, and a dorsal strip for attachment of
the base, there is a quadrilateral facet for articulation with the trapez- the radial head of the second dorsal interosseous.
ium, and just dorsal to this facet, a rough impression marks the attach-
ment of extensor carpi radialis longus. On the palmar surface, a small Third metacarpal
tubercle or ridge receives flexor carpi radialis. The medial side of the The third metacarpal has a short styloid process, projecting proximally
base articulates with that of the third metacarpal by a long facet, cen- from the radial side of the dorsal surface (see Figs 50.8–50.9; Fig.
trally narrowed. The shaft is prismatic in section and longitudinally 50.16C). Its base articulates with the capitate by a facet anteriorly
curved, convex dorsally, concave towards the palm. Its dorsal surface is convex but dorsally concave where it invades the styloid process on the
distally broad but proximally narrows to a ridge that is covered by lateral aspect of its base. A strip-like facet, constricted centrally, articu-


extensor tendons of the index finger. Its converging borders begin at the lates with the bases of the second metacarpal (laterally) and the fourth
tubercles, one on each side of its head for the attachment of collateral metacarpal (medially), the latter by two oval facets. The palmar facet
ligaments. Proximally, the lateral surface inclines dorsally for the ulnar may be absent; less frequently, the facets are connected proximally by
head of the first dorsal interosseous. The medial surface inclines simi- a narrow bridge. The palmar surface of the base receives a slip from the
larly, and is divided by a faint ridge into a palmar strip for attachment tendon of flexor carpi radialis; extensor carpi radialis brevis is attached


Bones
871
05
RETPAHC
A. First metacarpal
Eighth week
Unite 15 to 18 years
Second to fourth year
Twelfth week
Unite 15 to 18 years
Second to fourth year
Tenth week
For trapezium
Unite 15 to 18 years Palmar aspect Lateral aspect
Second year
B. Second metacarpal C. Third metacarpal
1.5 to 2.5 years
Unite 15–19 years
Ninth week
Ninth week
Unite 15–17 years
Hamate:third month
Second to third year
Pisiform:
Trapezium:4 to 5 years 9–12 years
Trapezoid:4 to 5 years
Triquetrum:third year
Capitate:second month
Scaphoid:4 to 5 years Lunate:fourth year
Fig. 50.15 The approximate dates of ossification of the individual bones
of the hand and their epiphyses.
For trapezoid For capitate For capitate For capitate
For trapezium For third metacarpal For second metacarpal For fourth metacarpal
Styloid process
to its dorsal surface, beyond the styloid process. The shaft resembles
that of the second metacarpal. The ulnar head of the second dorsal Lateral aspect Medial aspect Dorsolateral aspect Medial aspect
interosseous is attached to its lateral surface; the radial head of the third
dorsal interosseous is attached to its medial surface, and the transverse D. Fourth metacarpal E. Fifth metacarpal
head of adductor pollicis is attached to the intervening palmar ridge in
its distal two-thirds. Its dorsal surface is covered by the extensor tendon.
Fourth metacarpal
The fourth metacarpal is shorter and thinner than the second and third
(see Figs 50.8–50.9; Fig. 50.16D). On its base, it displays two lateral
oval facets for articulation with the base of the third metacarpal; the
dorsal is usually larger and proximally in contact with the capitate. A
single medial elongated facet is for articulation with the base of the fifth


metacarpal. The quadrangular proximal surface articulates with the
hamate; it is anteriorly convex and dorsally concave. The shaft is like
the second, but a faint ridge on its lateral surface separates the attach-
ments of the third palmar interosseous and the ulnar head of the third
dorsal interosseous. The radial head of the fourth dorsal interosseous
is attached to the medial surface.
For capitate For fifth metacarpal For hamate For hamate
Fifth metacarpal
For third metacarpal For hamate For fourth metacarpal
The fifth metacarpal (see Figs 50.8–50.9; Fig. 50.16E) differs in its
Lateral aspect Medial aspect Lateral aspect Medial aspect
medial basal surface, which is non-articular and bears a tubercle for
extensor carpi ulnaris. The lateral basal surface is a facet, transversely Fig. 50.16 Disarticulated metacarpal bones.
concave, convex from palm to dorsum, for articulation with the hamate.
A lateral strip articulates with the base of the fourth metacarpal. The
shaft bears a triangular dorsal area that almost reaches the base; the
lateral surface inclines dorsally only at its proximal end. Opponens year in females, early in the third year in males, uniting before the fif-
digiti minimi is attached to the medial surface. The lateral surface is teenth year in females and seventeenth in males. Sometimes, the styloid
divided by a ridge, which is sometimes sharp, into a palmar strip for process of the third metacarpal is a separate ossicle. The thumb meta-
the attachment of the fourth palmar interosseous and a dorsal strip for carpal ossifies like a phalanx, and some authorities therefore consider
the ulnar part of the fourth dorsal interosseous. that the thumb skeleton consists of three phalanges. Others believe that
the distal phalanx represents fused middle and distal phalanges, a con-
Ossification
dition occasionally observed in the fifth toe. When the thumb has three
phalanges, the metacarpal has a distal and a proximal epiphysis. It


Each metacarpal ossifies from a primary centre for the shaft and a sec- occasionally bifurcates distally. When it does, the medial branch has no
ondary centre that is in the base of the first metacarpal and in the heads distal epiphysis and bears two phalanges, while the lateral branch shows
of the other four (see Figs 50.11–50.15). Ossification begins in the a distal epiphysis, and three phalanges. The existence of only a distal
midshaft about the ninth week. Centres for the second to fifth metacar- metacarpal epiphysis may be associated with a greater range of move-
pal heads appear in that order in the second year in females, and ment at the metacarpophalangeal joint. In the thumb, the carpometa-
between 11 to 21 years in males. They unite with the shafts about the carpal joint has the wider range, and the first metacarpal has a basal
2 2
fifteenth or sixteenth year in females, and the eighteenth or nineteenth epiphysis. A distal epiphysis may appear in the first, and a proximal
in males. The first metacarpal base begins to ossify late in the second epiphysis in the second, metacarpal.


WRiST And HAnd
872
6
nOiTCES
A B C
Dorsolateral Palmar transverse
scaphotrapezial interosseous
trapezoid Dorsal transverse interosseous Dorsolateral
Pisohamate scaphotrapezial
Transverse trapezoid
Triquetro-hamate
Scaphocapitate carpal
Radioscaphoid Radiotriquetral
Palmar lunotriquetral
Dorsaol
intercarpal
Radioscaphoid
-capitate
Long radioulnate
Short radioulnate Ulnotriquetral Dorsal lunotriquetral Dorsal scapholunate
Ulnocapitate Palmar scapholunate Ulnolunate
Fig. 50.17 Joints and ligaments of the left hand. (A) Palmar aspect: extrinsic ligaments. (B) Palmar aspect: intrinsic ligaments. (C) Dorsal aspect.
PHALANGES proximal phalanges in the tenth, and middle phalanges in the eleventh
week or later. Epiphyseal centres appear in proximal phalanges early in
There are 14 phalanges, three in each finger and two in the thumb (see the second year (females), or later in the same year (males), and in
Fig. 50.15). Each has a head, shaft and proximal base. The shaft tapers middle and distal phalanges in the second year (females), or third or
distally, its dorsal surface transversely convex. The palmar surface is fourth year (males). All epiphyses unite about the fifteenth to sixteenth
transversely flat but gently concave anteriorly in its long axis. The bases year in females, and seventeenth to eighteenth year in males.
of the proximal phalanges carry concave, oval facets adapted to the
metacarpal heads. Their own heads are smoothly grooved like pulleys
and encroach more on to the palmar surfaces. The bases of the middle JOINTS
phalanges carry two concave facets separated by a smooth ridge, con-
forming to the heads of the proximal phalanges. The bases of the distal RADIOCARPAL (WRIST) JOINT
phalanges are adapted to the pulley-like heads of the middle phalanges.


The heads of the distal phalanges are non-articular and carry a rough, Articulating surfaces The radiocarpal joint is a synovial, biaxial
crescentic palmar tuberosity, to which the pulps of the fingertips are and ellipsoid joint formed by articulation of the distal end of the radius
attached. and the articular disc of the triangular fibrocartilage with the scaphoid,
Articular ligaments and numerous muscles are attached to the lunate and triquetrum (Figs 50.17–50.18). In the neutral position of
phalanges. The tendon of flexor digitorum profundus is attached to the the wrist, only the scaphoid and lunate are in contact with the radius
palmar aspect of the base of the phalanx and the tendon of extensor and articular disc; the triquetrum comes into apposition with the disc
digitorum to its dorsal surface. The tendon of flexor digitorum super- only in full adduction of the wrist joint. The radial articular surface and
ficialis and its fibrous sheath are attached to the sides of the middle distal discal surface form an almost elliptical, concave surface with a
phalanx, and a part of extensor digitorum is attached to the base dor- transverse long axis. The radial surface is bisected by a low ridge into
sally. The fibrous flexor sheath is attached to the sides of a proximal two concavities. A similar ridge usually appears between the medial
phalanx, part of the corresponding dorsal interosseous is attached to its radial concavity and the concave distal discal surface. The proximal
base laterally, and another dorsal interosseous is attached medially. articular surfaces of the scaphoid, lunate and triquetrum and their
The phalanges of the little finger and the thumb differ. Abductor and interosseous ligaments form a smooth convex surface that is received
flexor digiti minimi are attached to the medial side of the base of the into the proximal concavity.
proximal phalanx of the little finger. The tendon of extensor pollicis
brevis and the oblique head of adductor pollicis (dorsally), and the Fibrous capsule The fibrous capsule is lined by synovial membrane


oblique and transverse heads of adductor pollicis, sometimes conjoined
that is usually separate from that of the distal radio-ulnar and intercar-
with the first palmar interosseous (medially), are attached to the base
pal joints. A protruding prestyloid recess (recessus sacciformis), anterior
of the proximal phalanx of the thumb.
to the articular disc, is present and ascends close to the styloid process.
The recess is bounded distally by the fibrocartilaginous meniscus, which
Ossification
projects from the ulnar collateral ligament between the tip of the ulnar
styloid process and the triquetrum; both are clothed with hyaline articu-
Phalanges are ossified from a primary centre for the shaft and a proxi- lar cartilage. The meniscus may ossify. The capsule is strengthened by
mal epiphysial centre (see Figs 50.11–50.15). Ossification begins pre- palmar radiocarpal and ulnocarpal, dorsal radiocarpal and radial and
natally in shafts as follows: distal phalanges in the eighth or ninth week, ulnar collateral ligaments.


Joints
873
05
RETPAHC
1 13
14 7
2 1
3 15 1 6 8
4 2
5 7 9
6 16 2
7 3 10
3
4
8 9 4 5 8 9 5 11
10 17
11 6 12
12 A 18 B 10 C
Fig. 50.18 Magnetic resonance image (MRI) of the pronated left wrist. A, An axial view at the level of the distal radio-ulnar joint (compare with Fig. 49.8).
Key: 1, extensor pollicis longus; 2, extensor carpi radialis brevis; 3, extensor carpi radialis longus; 4, radius; 5, extensor pollicis brevis; 6, abductor
pollicis longus; 7, flexor pollicis longus; 8, radial artery; 9, median nerve; 10, flexor carpi radialis; 11, flexor digitorum superficialis; 12, palmaris longus;
13, extensor digitorum and extensor indicis; 14, extensor digiti minimi; 15, extensor carpi ulnaris; 16, ulna; 17, flexor digitorum profundus; 18, flexor carpi
ulnaris. B, An axial view at the level of the carpal tunnel. Key: 1, trapezoid; 2, trapezium; 3, flexor digitorum profundus; 4, median nerve; 5, thenar
muscles; 6, capitate; 7, hamate; 8, flexor digitorum superficialis; 9, hypothenar muscles; 10, ulnar artery and nerve. C, Coronal view demonstrating
normal bony anatomy and the triangular fibrocartilage: dorsal aspect. Key: 1, base of fifth metacarpal; 2, hamate; 3, triquetrum; 4, lunate; 5, triangular