carpi ulnaris places a lesion in the arm. Paralysis confined to the hand have been ruptured evokes sensations usually described as a wave or
places a lesion in the distal half of the forearm. Preservation of the surge of pins and needles into the cutaneous distribution of the nerve.
hypothenar muscles with paralysis of the other hand muscles inner This is Tinel’s sign and it is a most useful aid to diagnosis. The sign is
vated by the ulnar nerve places a lesion in the proximal part of the palm elicited on the day of injury in most conscious patients. It indicates not
of the hand. There is no cutaneous sensory loss in a palsy of the deep only where the nerve has been injured but also the fact that at least
branch of the ulnar nerve. The posture of the digits is characteristic in some axons have been ruptured. Tinel’s sign can be detected from such
ulnar nerve lesions. ‘motor’ nerves as the posterior interosseous nerve; sensory symptoms
The examiner should bear in mind the possibility of anatomical radiate into muscular territory rather than into skin. It is more difficult
variation and also the ability for other muscles to compensate for the to elicit the sign over deepseated nerves such as the axillary, eighth
actions of those paralysed by what are termed ‘trick movements’. In fact, cervical or first thoracic nerves.
these muscles are acting appropriately and the movements are real
Eliciting Tinel’s sign in closed lesions
enough (see Fig. 46.23B).
The examiner’s finger percusses along the course of the nerve from distal
Depth of a lesion
to proximal, starting below the presumed level of lesion. The patient is
The distinction between conduction block and severance of an axon asked to say when the advancing finger elicits a wave or a surge of pins
(axonotmesis or neurotmesis) is sometimes difficult. Serious injuries and needles or abnormal sensations, which may be painful, into the
are likely to cause serious lesions of nerves. Severance of a nerve with distribution of the nerve, which must be clearly indicated by the exam
a cutaneous sensory component will lead to welldefined loss of sensi iner. The level of the sign should be measured from a fixed bony point


bility and to complete motor, sudomotor and vasomotor paralysis in and the distance recorded. At times, the examination is painful and
the distribution of the nerve. Simple conduction block is likely to patients need to be warned of this. A Tinel’s sign that remains static at
produce a patchy loss of sensibility and a patchy motor loss. Further, it the level of a lesion strongly suggests rupture of the nerve or persisting
is likely to bear more heavily on the large axons than on the small ones; local conditions inimical to spontaneous regeneration.


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Common examples of the classical compartment syndrome in the about 30 minutes, although conduction within the nerve itself can still
upper limb occur in the flexor and extensor compartments of the be detected for up to another 20 minutes. However, direct stimulation
forearm. Although nerve conduction is lost before muscle contractility, of the muscle provokes a twitch that can be elicited for up to several
ischaemia is more likely to produce infarction of muscle than necrosis hours. Indeed, it is the loss of this direct response that signifies impend
of nerve. Decompression of a nerve embedded within muscle that has ing death of the muscle, and with it, death of the limb. The earliest
become fibrosed by ischaemia usually leads to relief of pain and con nerve fibres to suffer are the largest, i.e. those conveying vibration and
siderable improvement in sensation and sympathetic function, even proprioception sense.
when delayed for some months.
Ischaemia and acute compression within
Anoxia occurs either because of cessation of flow through a main
axial artery or as a result of increasing pressure within an osseofascial neurovascular fascial compartments
compartment caused by bleeding, infusion of fluid or sepsis. It destroys Sleeves of fascia surround main nerves and main vessels in some
the integrity of the cell membrane and capillary endothelium, which regions, an arrangement that predisposes nerves to injury from ischae
means that the homeostatic balance between the intravascular, extracel mia or compression, or both. The ventral (anterior) primary rami of
lular and intracellular spaces is lost. Tissue death is imminent. C7, C8 and T1 are enclosed in quite a rigid space after they enter the
The increased permeability of the vascular endothelium leads to an posterior triangle of the neck. This is bounded, posteriorly, by the dorsal
increase in intracompartmental pressure by exudation, which collapses part of the first rib, the transverse processes of the cervical vertebrae and
the lowpressure lymphatic and venous systems. The final event is the by the fascia of levator scapulae. The nerves are embraced by scalenus


closure or obstruction of perfusing arterioles to muscles and the extrin anterior and scalenus medius, both of which are invested in an unyield
sic supply to nerves, when tissue or extravascular pressure exceeds the ing fascia. This is one envelope of the prevertebral fascia that also serves
cortical closing pressure of those vessels. The vicious circle is complete. to bind the phrenic nerve down to the anterior face of scalenus anterior.
The fluid entering the compartment cannot get out and continues to The prevertebral fascia is particularly well developed in front of the
leak into the compartment until the pressure is so high that inflow is vertebral column and also at the base of the posterior triangle, where
blocked. Increasing intracompartmental pressure occurs when the col it envelops C7, C8 and T1, the phrenic nerve, the cervical sympathetic
lateral circulation is inadequate after occlusion of the main artery or chain, and the subclavian and vertebral arteries. Infusion of relatively
after restoration of flow through that vessel, unless the compartments large volumes of fluid, from 10 to 20 ml, deep to the prevertebral fascia
have been decompressed adequately by fasciotomy. The vascular anas for the purpose of inducing regional block may cause tamponade of
tomoses about the joints of the upper limb provide a richer collateral the radicular vessels that enter the spinal canal and contribute to the
circulation than those found in the lower limb. In a study of nearly anterior spinal artery. Wilbourn (2005) has described the medial bra
2,500 World War II battle casualties, at a time when ligation of damaged chial fascial compartment, which extends from the axilla to the elbow
arteries was common, ligation of the popliteal artery led to amputation and is bounded by the tough medial intramuscular septum and the
in 346 of 502 limbs. In contrast, the incidence of amputation after axillary sheath. Bleeding into this compartment is responsible for the
ligation was about onequarter for the subclavian artery, onethird for majority of infraclavicular plexopathies that follow regional block, and
the axillary artery and more than onehalf when the brachial artery was for many of the neurological lesions that result from closed or even


ligated proximal to the profunda brachii artery. These figures are cer open injuries in this region. The anterior interosseous nerve and its
tainly lower in the less contaminated injuries of civilian life, but some accompanying artery may be damaged by compression because of
degree of postischaemic fibrosis is almost inevitable after failure to swelling in the deepest part of the flexor compartment of the forearm.
repair these vessels. The principles of arterial repair include urgent The ulnar nerve, accompanied by the ulnar artery, lies in a discrete
restoration of flow by repair of the artery and restoration of tissue per fascial compartment in the distal twothirds of the forearm.
fusion by decompression. Temporary intraluminal shunts are invalua Bleeding into the axillary fascia (the medial antebrachial compart
ble, as they buy time and permit adequate stabilization of the skeleton. ment) causes a characteristic, progressive lesion. There is, almost always,
Application of these principles in current conflicts ensures a remarkably pain accompanied by dysaesthesiae; loss of sensation soon follows and
high rate of limb survival and a remarkably low incidence of post then, over the next 2–3 hours, paralysis ensues. Wilbourn’s comment
ischaemic fibrosis. bears repeating:
Flow through the brachial artery in adults and in children has been
Distal pulses are normal as they are with most compartment syndromes
measured by highresolution ultrasonography. Flow was calculated by
the Laplace equation: BF(blood flow) = [π × (D/2)]2 × FV(flow velocity). because the elevated pressure, although sufficient to collapse the vasae
nervori, is far below mean arterial pressure. Ultrasound, MR and CT
The mean diameter of the brachial artery in children aged between 4
may reveal the vascular lesion, but, considering the very brief time
and 5 years is 2.7 mm, which provides a resting flow of about 200 ml
available for surgical decompression before irreversible nerve damage
per minute. The significance of the diameter of the vessel is emphasized
occurs, obtaining these is rarely justified.
by Poiseuille’s law. This is the physical law describing the volume of


flow (Φ) of an incompressible uniform viscous liquid, where R is the In one series of 16 patients (Stenning et al 2005), there was, in all cases,
internal radius of the tube, P the pressure difference between the two an injury to the axillary artery or one of its offsets, caused by dislocation
ends, ɳ the dynamic fluid viscosity and L the total length of the tube. of the shoulder or fracture of the proximal humerus. The diagnosis of
continuing bleeding into the axillary sheath was made by the delayed
πR4[∆P]
Φ= onset of nerve palsy or the deepening of the lesion whilst under obser
8η L vation. A favourable outcome was seen in 87 nerve palsies, where urgent
repair of the artery and decompression of the axillary sheath were per
The diameter of the superior ulnar collateral artery at the elbow in
formed. However, delay in diagnosis and treatment may lead to perma
a 5yearold child is, at most, 1 mm. This calibre provides flow of about
nent loss of function (see Fig. 6.2.17).
20 ml per minute, assuming that the pressure gradient is the same as
that in the brachial artery itself. These facts must be borne in mind by Case report After a fracture/dislocation of the shoulder in a 59year
any clinician inclined to the view that cessation of flow through the
old man, the patient’s complaints of pain and the signs of a deepening
brachial artery is a matter of little consequence. The collateral channels
lesion were not appreciated for several days. Angiography showed
take hours or days to develop and may be compromised by the original
bleeding from the subscapular artery. Two unsuccessful attempts were
injury or during operation. The radial and ulnar nerves are often
made to occlude this by embolization. The patient was reviewed at
entrapped or compressed in fracture dislocations at the elbow, blocking
6 weeks in right heart failure; haemoglobin was 4.9 g/litre (49 g/dl). He
flow through the ulnar and radial collateral systems that accompany
was in great pain and there was a total and deep plexopathy. A magnetic
these nerves.
resonance imaging (MRI) scan showed an enormous haematoma


The presence of peripheral pulses does not indicate adequate per
occupying the axilla and the arm, and suggested continuing bleeding.
fusion of the deep intracompartmental tissues; neither does the per
Treatment was simple: the axillary artery was exposed and controlled
fusion of skin or the nail bed when pulses are absent. The cardinal
above pectoralis minor and the brachial artery exposed and controlled
symptom of ischaemic anoxia is severe pain and the cardinal sign is
in the arm. More than 4 litres of altered blood were removed from the
loss of nerve conduction. This can be confirmed during exposure of
sac. The defect in the axillary artery was, at most, 2 mm in diameter
limb nerves with an inflated tourniquet cuff in position proximally.
and it was closed by direct suture. The pain was relieved and there was
For about 20 minutes, stimulation of the nerve evokes a brisk mus
gradual recovery of the nerves, but the small muscles of the hand never
cular response as a consequence of transmission through the neu
recovered.
romuscular junction. This response diminishes and disappears after


Surface anatomy
787
64
rETPaHC
C5
Stellate ganglion
Eighth cervical nerve
C6 Lower trunk of brachial plexus
First intercostal nerve
First posterior intercostal vessels
C7
Rib 1
Superior costotransverse ligament
T1
Superior intercostal vein
Rib 2
T2
Rib 3
T3
T4
Fig . 46 .16 The relations of the left cervicothoracic (stellate) ganglion . (Courtesy of Rolfe Birch, all rights reserved, published in Birch R, Surgical
Disorders of the Peripheral Nerve, 2nd ed, 2011 . Springer-Verlag, London .)
The infraclavicular fossa (deltopectoral triangle) is visible as a small and the head of the radius covered by the anular ligament inferiorly.
depression located inferior to the clavicle between the clavicular origins Rotations of the radial head are palpable during forearm pronation and
of pectoralis major and deltoid, at the junction of the convex medial supination. The humeroradial part of the elbow joint forms a palpable
and concave lateral portions of the clavicle (see Fig. 46.29A). The apex transverse depression between the lateral epicondyle and the radial
of the coracoid process lies approximately 2.5 cm below the clavicle head.
immediately lateral to this fossa, and is covered by the anterior fibres The posterior surface of the olecranon is subcutaneous and tapers as
of deltoid. Deep palpation lateral to the coracoid process and through it passes inferiorly. When the elbow is extended, the apex of the ole
deltoid reveals the lesser tubercle of the humerus below the tip of the cranon lies on a line level with the medial and lateral humeral epi
acromion. The greater tubercle of the humerus is the most lateral bony condyles (see Fig. 46.29B). When the elbow is flexed, the apex of the
point in the shoulder region and is palpable inferolateral to the olecranon descends and the three bony points then form a triangle. This
acromion. The greater and lesser tubercles can be felt moving under an relationship is lost following elbow dislocation.


examining finger during lateral and medial humeral rotation. The verti The elbow joint is situated 2 cm below a line joining the two
cal groove or indentation of the intertubercular (bicipital) groove is humeral epicondyles. It slopes downwards and medially from its lateral
palpable between the tubercles; regional tenderness occurs in bicipital extremity. When the elbow is fully extended with the forearm and hand
tendinitis. When the arm is abducted, the head of the humerus can be in supination, the carrying angle is normally 165° in females and 175°
palpated on deep pressure in the apex of the axilla. in males. The angle is obscured in full forearm pronation and disap
The shaft of the humerus is covered by overlying muscles and is not pears on full elbow flexion, when the shafts of the ulna and humerus
easily palpable. Distally, the medial humeral epicondyle is both visible come to lie in the same plane. The elbow joint can be accessed with a
and palpable, particularly when the elbow is flexed, and can be traced needle from a posterior perspective via the anconeus triangle; the
proximally to the medial supracondylar ridge. The ulnar nerve passes borders of the triangle join the olecranon, radial head and lateral
posterior to the medial epicondyle and can be rolled from side to side epicondyle.
just proximal to the epicondyle (Fig. 46.29B). The lateral epicondyle is The posterior border of the ulna is subcutaneous and palpable from
less prominent, but its posterior surface is palpable and its lateral the olecranon superiorly to the styloid process inferiorly (see Fig.
margin can be traced proximally on deep palpation to the lateral supra 46.29C). Its position corresponds to the longitudinal furrow that is
condylar ridge. Inspection of the posterior surface of an extended elbow visible on the posterior forearm when the elbow is fully flexed and
reveals a depression lateral to the midline, bounded laterally by the marks the border between the anterior and posterior forearm compart
fleshy elevation formed by the superficial forearm extensor muscles, and ments. In contrast, the radial shaft is covered by muscles and can only


medially by the lateral side of the olecranon. The floor of this depres be felt indistinctly. The rounded head of the ulna forms a surface eleva
sion contains the posterior surface of the lateral epicondyle superiorly, tion on the medial part of the posterior aspect of the wrist (Fig. 46.30B),


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6
NOITCES
especially when the hand is pronated. The ulnar styloid process projects It can be moved over the articular surface of the triquetrum when the
distally from the posteromedial aspect of the ulnar head. wrist is passively flexed. The hook of the hamate lies approximately
The expanded distal end of the radius forms a slight surface elevation 2.5 cm distal to the pisiform, in line with the ulnar border of the ring
on the lateral side of the wrist and can be traced downwards to the finger. It can be felt on deep palpation, and the superficial division of
radial styloid process. The posterior aspect of the lower end of the radius the ulnar nerve can be rolled from side to side over the tip of the hook.
is partly obscured by the extensor tendons but can be palpated without The tubercle of the scaphoid is situated at the base of the thenar emi
difficulty. The prominent dorsal radial (Lister’s) tubercle is both visible nence, in line with the tendon of flexor carpi radialis, and in many
and palpable, and aligns with the web space between digits 2 and 3 individuals forms a small visible elevation. Immediately distal to it, but
(Fig. 46.30B–C). The tendon of extensor pollicis longus in extensor covered by the muscles of the thenar eminence, the tubercle of the
compartment 3 sits medial to the tubercle, and the tendons of extensor trapezium can be identified on deep palpation.
carpi radialis longus and brevis sit lateral to the tubercle in compart The dorsal aspects of the trapezium and of each of the metacarpal
ment 2. bones are partially palpable around the margins of the corresponding
The wrist joint is identified between the distal ends of the radius and extensor tendons (see Fig. 46.30B). The heads of the metacarpal bones
ulna and the proximal carpus on flexion and extension of the wrist. The form the prominences of the knuckles, and are most obvious during


line of the wrist joint corresponds to a line, convex superiorly, joining digit flexion. On the dorsal hand, the metacarpophalangeal joint line
the radial and ulnar styloid processes. Its position is also marked by the forms a palpable depression lateral to the digital extensor tendon, and
proximal of the two transverse anterior wrist creases (Fig. 46.30A). The alternating digit flexion/extension aids identification. The joint can be
radial styloid process normally sits 1 cm distal to the ulnar styloid aspirated/injected from this perspective. Palpation distal to the meta
process. Alteration of this arrangement can indicate fracture. carpal head reveals the flared base of the corresponding proximal
Four of the carpal bones are palpable. The pisiform is both visible phalanx. The interphalangeal joints are palpable on the dorsal aspect
and palpable on the palmar aspect of the medial wrist at the base of of a flexed digit just distal to the prominences formed by the heads of
the hypothenar eminence. It is often overlain by the distal wrist crease. the proximal and middle phalanges.
A B
2
1
3
1
2 4
3 4
6
5 7 5
6
8
9
4 3
7
8
15
9
10
13
12 11
10
14
11
15 12
13
Fig . 46 .29 Surface anatomy of the upper limb . A, The anterior aspect of the left pectoral girdle, arm and elbow . Key: 1, sternoclavicular joint; 2, clavicle;
3, infraclavicular fossa/deltopectoral triangle, and deltopectoral groove running inferolaterally; 4, acromion; 5, deltoid; 6, pectoralis major; 7, lateral head
of triceps; 8, biceps brachii; 9, median nerve and brachial artery running anterior to triceps medial head; 10, epicondylar line and borders of cubital fossa


(blue); 11, brachioradialis; 12, pronator teres; 13, biceps tendon (black) and aponeurosis (grey) passing inferomedially; 14, extensor muscle mass; 15,
cephalic vein . B, The anterior aspect of the left elbow, forearm and hand . Key: 1, radial nerve; 2, brachial artery; 3, median nerve; 4, ulnar nerve (dashed
part of line shows nerve passing posterior to medial epicondyle); 5, zone of radial nerve bifurcation (white): 1 .0 ± 2 .8 cm distal to the lateral epicondyle; 6,
cubital fossa borders (blue); 7, biceps tendon with brachial artery bifurcation medially; 8, ulnar artery; 9, radial artery; 10, pisiform with Guyon’s canal
(blue) laterally; 11, deep palmar arch; 12, superficial palmar arch; 13, plane of fully extended thumb .


Surface anatomy
789
64
rETPaHC
The flexor retinaculum, and therefore the surface position of the
C
carpal tunnel, can be mapped according to its palpable bony attach
ments (see Fig. 46.30A). The distal border is concave inferiorly and is
1 marked by a curved line that joins the tubercle of the trapezium to the
hook of the hamate. Its proximal border is marked by a curved line,
2 concave superiorly, that joins the tubercle of the scaphoid to the pisi
form. The dominant, most distal, wrist crease normally sits distal to the
4 3 3 lunate and overlies pisiform and the proximal edge of the flexor reti
naculum. The carpal tunnel passes distal to this crease for 2.5–3 cm.
5
6 MUSCULOTENDINOUS LANDMARKS
Deltoid can be identified when the arm is abducted against resistance.
7
The deltoid tendon is palpable approximately halfway down the lateral
aspect of the humerus. Its anterior border can be traced superomedially
from the anterior aspect of the humerus, across the tendon of pectoralis
major, to form the lateral boundary of the infraclavicular fossa (see Fig.
46.29A, Video 46.1). The posterior border runs superomedially from
8 the posterior aspect of the deltoid tendon and reaches the crest of the
10 scapular spine near its medial end. The normal rounded contour of
9 the shoulder is produced by deltoid covering the lateral aspect of the
11 greater tubercle of the humerus. Shoulder dislocation results in the loss
of the normal rounded contour of the shoulder because the greater
tubercle is displaced medially, and deltoid consequently descends verti
cally to its humeral attachment. Supraspinatus and infraspinatus are
visible and palpable above and below the scapular spine, respectively
12 (see Fig. 46.29C).
13 The lower border of pectoralis major forms the anterior axillary fold.
14 It is visible and palpable when an abducted shoulder is adducted
against resistance, e.g. by firmly pressing a hand on to the hip. The
15
clavicular head of pectoralis major can be felt and seen to contract when


flexing the shoulder to a right angle against resistance; the sternocostal
16 head becomes visible when extending a flexed shoulder against
resistance.
The posterior axillary fold, produced by latissimus dorsi and the
underlying teres major, reaches a lower level on the humerus than the
anterior axillary fold. When the abducted shoulder is adducted against
resistance, the posterior axillary fold is accentuated and the lateral
border of latissimus dorsi can be traced inferomedially to its attachment
to the iliac crest. When the upper limb is raised above the head, the
17 lower five or six serrations of serratus anterior are visible on the lateral
aspect of the thorax; they pass downwards and forwards to interdigitate
with the serrations of external oblique.
Biceps brachii produces a visible elevation on the anterior arm and
18
shallow furrows mark its medial and lateral borders (see Fig. 46.29A).
It diminishes superiorly where it is covered by pectoralis major, and
20
19 inferiorly where it tapers to the biceps tendon just above the elbow
joint. Flexion of the elbow against resistance aids identification of the
muscle and of the bicipital tendon, which can be held between finger
and thumb and traced down into the cubital fossa. With the elbow held
in this position, the sharp upper margin of the bicipital aponeurosis
can be traced passing inferomedially over the elevation produced by the
superficial group of forearm flexor muscles. Coracobrachialis emerges
from the lateral axillary wall and forms a rounded ridge on the upper
part of the medial side of biceps.
On the posterior arm, the lateral head of triceps forms a laterally
placed elevation, inferior to the posterior border of deltoid (see Fig.
46.29C). Triceps can be made visible by extending the elbow against
resistance. On the medial side, the fleshy mass produced by the long
Fig . 46 .29, cont’d C, A posterior view of the left pectoral girdle, arm, head of triceps passes superiorly and disappears deep to deltoid.


elbow and forearm . Key: 1, trapezius; 2, supraspinatus; 3, spine of Brachioradialis is the most superficial muscle on the lateral side of
scapula; 4, acromion; 5, infraspinatus; 6, zone of axillary nerve passing the forearm. When the elbow is flexed against resistance whilst in a mid
around proximal humerus (white): approximately 6 .0 cm from proximal pronationsupination position, brachioradialis stands out as a promi
humeral margin; 7, deltoid; 8, radial nerve and its zone of passage around nent ridge extending upwards beyond the level of the elbow joint to
spiral groove (white): enters the spiral groove approximately 46% and
the lower lateral side of the arm. The medial (ulnar) border of brachio
leaves it approximately 60% of the way down a line from greater tubercle
radialis marks the boundary between the anterior and posterior forearm
to lateral epicondyle; 9, triceps, long head; 10, triceps, lateral head; 11,
compartments.
radial nerve piercing intermuscular septum approximately 66% of the way
The three borders of the cubital fossa can be mapped out anterior
down a line from greater tubercle to lateral epicondyle; 12, triceps tendon;
to the elbow by a line joining the medial and lateral humeral epi
13, lateral epicondyle and borders of anconeus triangle shown as blue
condyles (superiorly), brachioradialis (laterally) and pronator teres
dashed line; 14, olecranon and olecronon bursa; 15, radial head; 16, zone
of posterior interosseous nerve winding around radial neck (white): (medially) (see Fig. 46.29A–B). Pronator teres passes inferolaterally
approximately 2 .5 cm distal to radial head; 17, superficial radial nerve from the medial epicondyle to a point approximately halfway down the
emerging from between the tendons of brachioradialis and extensor carpi radial shaft; its rounded belly is visible during resisted forearm


radialis longus approximately 8 .5 cm proximal to radial styloid process; pronation.
18, posterior border of ulna; 19, ulnar head; 20, dorsal radial tubercle . The fleshy mass of the superficial forearm flexors is visible and pal
pable in the upper medial forearm, and that of the extensor muscle
mass is visible in the upper lateral forearm. The line of travel of the
superficial forearm muscles can be mapped out according to their


PECTOral GIrdlE aNd UPPEr lImb: OvErvIEw aNd SUrfaCE aNaTOmy
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6
NOITCES
A B C
12
4 3 2 1 1 4 9 11
5 10
6
7 1 2 B 3 4 5 A 6 2
9 8 6
10 5
7
12 11
13
14 5
15 6
16 10 9 8 8
3 7
9
11
17
Fig . 46 .30 The surface anatomy of the wrist and hand . A, Key: 1, radial artery; 2, flexor carpi radialis tendon; 3, median nerve; 4, ulnar nerve; 5, palmaris
longus tendon; 6, flexor carpi ulnaris tendon; 7, proximal transverse wrist crease: marks the line of the wrist joint; 8, distal transverse wrist crease: marks
the proximal boundary of the carpal tunnel; 9, scaphoid tubercle; 10, pisiform (black oval): aligns with distal wrist crease; 11, trapezium tubercle;
12, hook of hamate and superficial branch of ulnar nerve passing anteriorly; 13, thenar eminence; 14, hypothenar eminence; 15, plane of deep palmar
arterial arch; 16, plane of superficial palmar arterial arch; 17, positions of palmar digital neurovascular bundles; shaded rectangle indicates position of
flexor retinaculum . B, Key: 1–6, first to sixth extensor compartments of the wrist; 7, wrist joint needle insertion point; 8, hypothenar eminence; 9, dorsal
venous network of the hand; 10, extensor pollicis longus tendon; 11, extensor tendon and metacarpophalangeal joint line; A, head of the ulna; B, dorsal
radial (Lister’s) tubercle . C, Key: 1, dorsal radial (Lister’s) tubercle; 2, wrist joint needle insertion point; 3, extensor digitorum tendon; 4, extensor


compartment 2, containing the tendons of extensors carpi radialis longus and brevis; 5, extensor pollicis longus tendon; 6, cephalic vein; 7, superficial
branch of radial nerve; 8, first dorsal interosseous muscle; 9, extensor compartment 1, containing abductor pollicis longus and extensor pollicis brevis;
10, radial styloid process; 11, radial artery; 12, flexor carpi radialis tendon .
attachment points. Inflammation of the common flexor or extensor tion of the superficial radial nerve, which can be rolled from side to
tendons can be indicated by tenderness to palpation over the respective side on the tendon. The cephalic vein passes over the roof of the snuff
muscle mass or humeral epicondyle. box, where it is visible and palpable, and the pulsation of the radial
Palpating lateral to flexor carpi radialis, 3–4 cm proximal to the wrist artery can be palpated deeply on its floor.
crease, reveals the muscle belly of flexor pollicis longus (flexing and The tendons located within the six extensor compartments of the
extending the thumb will confirm that the examining finger is correctly wrist are subcutaneous and palpable (see Fig. 46.30B). Compartment
placed). The area on the ulnar side of flexor carpi radialis tendon is 1 (containing abductor pollicis longus and extensor pollicis brevis) sits
packed with functionally important structures. The median nerve is over the lateral radius. Regional tenderness to palpation occurs in de
either covered by, or situated just lateral (radial) to, the tendon of pal Quervain’s tenosynovitis. Compartment 2 (containing extensors carpi
maris longus. The latter can be identified by gently pinching the tips of radialis longus and brevis) and 3 (containing extensor pollicis longus)
the digits together and partially flexing the wrist (see Fig. 46.30A). Near flank the lateral and medial sides of the dorsal radial (Lister’s) tubercle,


to the wrist, the median nerve lies very close to the skin and can, there respectively. Compartments 5 (containing extensor digiti minimi) and
fore, be injured by relatively superficial lacerations. When palmaris 6 (containing extensor carpi ulnaris) flank the posterior and medial
longus is absent, only a thin covering of subcutaneous fat and deep sides of the ulnar head, respectively. Compartment 4 (containing exten
fascia separate skin and nerve. The four tendons of flexor digitorum sors digitorum and indicis) sits between the ulnar head and compart
superficialis lie deep to the median nerve; the tendons to the middle ment 3. The tendons of extensors carpi radialis longus and brevis can
and ring fingers lie anterior to those for the index and little fingers as be identified on the dorsal carpus when the fist is clenched and relaxed.
they pass deep to the flexor retinaculum, and can be felt and, usually, The tendons of extensor digitorum are visible and palpable on the
seen to move during finger flexion/extension. Deeper still are the dorsal hand with the fingers fully extended. The tendon of extensor
tendons of flexor digitorum profundus. The broad tendon of flexor carpi ulnaris is palpable distal to the ulnar styloid as it crosses the wrist,
carpi ulnaris is easily palpated passing to the pisiform on the ulnar side with the wrist in extension and adduction. The first dorsal interosseous
of the anterior wrist; the ulnar nerve, artery and venae comitantes lie forms a visible fleshy mass on the lateral part of the dorsal hand
along its lateral (radial) edge. Any sharp injury that cuts through the between the index finger and thumb, especially whilst abducting the
tendon usually has enough energy to sever the ulnar neurovascular index finger against resistance.
bundle. The first metacarpal is both visible and palpable on the dorsolateral
When the thumb is fully extended, the depression of the anatomical hand. Its dorsal aspect forms the lateral border of the hand. The fleshy
snuffbox is seen on the lateral aspect of the wrist immediately distal elevation of the thenar eminence, produced by abductor and flexor


to the radial styloid process (see Fig. 46.30C). The snuffbox is bounded pollicis brevis overlying opponens pollicis, is located on the lateral
on its anterolateral (radial) side by the tendons of abductor pollicis palm (see Fig. 46.30A). The less prominent hypothenar eminence is
longus (laterally) and extensor pollicis brevis (immediately medial), located on the medial palm and is formed by the comparable muscles
and on its posteromedial/ulnar side by the tendon of extensor pollicis of the little finger. The medial aspect of the hypothenar eminence forms
longus. Running a finger along extensor pollicis brevis enables palpa the medial border of the hand.


Surface anatomy
791
64
rETPaHC
VESSELS, PULSES AND NERVES wrist, the cephalic vein consistently passes over the roof of the anatomi
cal snuffbox (see Fig. 46.30C) and the dorsolateral aspect of the distal
Arteries radius. Here, it sits next to the superficial branch of the radial nerve.
The cephalic vein ascends the anterolateral forearm and the lateral arm
in the groove lateral to biceps brachii. Superiorly, it ascends the delto
The brachial artery travels along the medial arm in the depression pos
pectoral groove to the infraclavicular fossa, where it pierces the clavi
terior to coracobrachialis and along the furrow to the medial side of
pectoral fascia to enter the axillary vein.
biceps, to a point just medial to the biceps tendon and level with the
The median cubital and basilic veins may be identified over the
radial head/neck (see Fig. 46.29A–B). Its pulsations are palpable along
cubital fossa. In the proximal forearm, the cephalic vein runs alongside
this line of travel and proximal to the bicipital aponeurosis, via com
the lateral cutaneous nerve of the forearm. The veins are frequently
pression against the humerus. Brachial artery catheterization just proxi
covered by fat, especially in the female, which makes them difficult to
mal to the aponeurosis is used for coronary angiography or cardiac
see. The median cubital vein usually arises from the cephalic vein
catheterization. The ability to compress the brachial artery against the
approximately 2.5 cm distal to the lateral epicondyle of the humerus,
humerus makes the arm the favoured site for noninvasive blood pres
and runs upwards and medially over the bicipital aponeurosis to join
sure measurement. The median nerve is intimately related to the bra
the basilic vein approximately 2.5 cm above the transverse crease of the
chial artery throughout its course in the arm. Proximally, it sits lateral
elbow. The median vein of the forearm drains the venous plexuses on
to the artery; then, around the midpoint of the arm, it passes anterior


the palmar surface of the hand. It ascends on the front of the forearm
to the artery and descends on its medial side to the cubital fossa.
and usually ends in either the basilic vein or the median cubital vein;
The radial and ulnar arteries originate in the anterior forearm at a
sometimes, it divides, just distal to the elbow, into two branches, one
point situated medial to the biceps tendon and level with the lower
of which joins the basilic vein and the other the cephalic vein.
head/neck of the radius (see Fig. 46.29B). From here, the ulnar artery
passes inferomedially to a point onethird of the way down flexor carpi Venepuncture at the elbow
ulnaris (which passes along a line joining the medial humeral epi
Commonly accessed superficial veins include the cephalic or median
condyle to the pisiform). The ulnar artery and nerve then pass inferiorly
cubital vein at the cubital fossa, and the dorsal venous network of
to a point just lateral to the pisiform along the line of flexor carpi
the hand. The cephalic vein may also be accessed over the distal
ulnaris, with the ulnar artery lying on the lateral (radial) side of the
radius and anatomical snuffbox. The latter site has many advantages
nerve. The radial artery passes inferolaterally through the forearm, from
for placing an indwelling cannula when a lengthy period is contem
its point of origin to a point just lateral to the tendon of flexor carpi
plated, although the vein lies close to the superficial branch of the
radialis, anterior to the distal radius. The upper part of its course can
radial nerve.
be represented by a line that passes deep to the medial part of the eleva
A high bifurcation of the brachial artery is seen occasionally and may
tion produced by brachioradialis on the anterior aspect of the forearm.
produce an anomalous superficial ulnar artery that descends superficial
It then passes posteriorly, deep to the tendons of abductor pollicis
to the common origin of the forearm flexor muscles. When this occurs,
longus and extensor pollicis brevis, and enters the anatomical snuff


the ulnar artery, although deep to the deep fascia, may lie subcutane
box, where its pulsations are palpable.
ously and pass superficial to the bicipital aponeurosis. Such an artery
The radial pulse is palpable on the anterior (volar) aspect of the wrist
is therefore at risk of puncture during median cubital vein access.
between the tendon of flexor carpi radialis medially and the radial
styloid process laterally. This is the simplest pulse to palpate during
Lymph nodes
routine patient examination. The pulse of the ulnar artery is usually
palpable on deep pressure lateral to the tendon of flexor carpi ulnaris
at the wrist. Supratrochlear lymph nodes (in reality, supraepicondylar nodes) lie
The position of the superficial palmar arterial arch is indicated by a next to the basilic vein. If enlarged, they may be palpated along the line
horizontal line, approximately 4 cm long, drawn at the level of the fully of the vein, a few centimetres above the elbow joint.
extended and partially abducted thumb (see Fig. 46.30A). A horizontal
line, approximately 4 cm long, running from a point just distal to the Nerves
hook of the hamate, indicates the position of the deep palmar arterial
arch. The deep arch is located approximately 1 cm proximal to the
The trunks of the brachial plexus lie in the posterior triangle of the neck
superficial arch. The digital neurovascular bundles pass along the
posterior to the subclavian artery (whose pulsations are palpable), in
medial and lateral sides of the dorsal and volar surfaces of the digits,
the angle between the clavicle and the lower posterior border of the
and can be anaesthetized in these positions via the web space.
clavicular head of sternocleidomastoid. The upper trunk can be pal
Sites for arterial cannulation pated by passing the fingers inferiorly along the vertical groove between
scalenus anterior and scalenus medius.
At the wrist, the radial artery is commonly used for arterial cannulation
The axillary nerve and circumflex humeral vessels pass around the
for arterial blood sampling and blood pressure monitoring. Throm
posterior and lateral aspects of the proximal humerus, close to the surgi


bosis or vasospasm of the radial artery at this site should not normally
cal neck, approximately 5 cm from the posterior edge, and 6 cm from
jeopardize the circulation to the hand since the interconnecting palmar
the anterior edge, of the acromion (Cetik et al 2006). Bono et al (2000)
arterial arches provide a collateral circulation to the hand. Allen’s test
found the axillary nerve to lie approximately 6 cm from the proximal
should be performed prior to any such procedure.
humerus, passing within approximately 2 cm of the surgical neck of the
humerus (see Fig. 46.29C).
allen’s test
The radial nerve passes inferolaterally along the spiral groove on the
Allen’s test examines the patency of the interconnection between the
posterior arm (see Fig. 46.29C). The distance from the acromion to a
superficial and deep palmar arches, and determines whether either
line passing through the humeral epicondyles can be used as a baseline
artery is capable of maintaining the arterial supply to the hand in isola
measurement; the radial nerve reaches the spiral groove approximately
tion. To perform the test, the radial and ulnar arteries of one hand are
46%, leaves it approximately 60%, and pierces the intermuscular
compressed by the examiner’s thumbs. The forearm is then elevated and
septum approximately 66% of the way down this line (Cox et al 2010,
the hand exsanguinated by clenching the fist. The hand is then opened
Cho et al 2013). The radial nerve then passes inferiorly, approximately
while arterial compression is continued. The palm of the hand appears
1 cm lateral to the tendon of biceps, and bifurcates into the posterior
pale, unless there is an anomalous arterial supply, e.g. from a persistent
interosseous and superficial radial nerves just distal to the lateral epi
median artery. The rapid return of a normal pink colour to the palmar
condyle (Cox et al 2010) (see Fig. 46.29B). The posterior interosseous
skin following removal of digital pressure from one of the arteries sug
nerve winds around the radial neck approximately 2.5 cm distal to the


gests that that artery is capable of perfusing the hand adequately in
radial head (Cox et al 2010); this is an important surgical consideration
isolation. If the palmar skin remains pale, it must be assumed either
when making an incision to expose the radial head. The nerve then
that there is a distal obstruction to the artery or that the artery cannot
passes inferiorly through the posterior forearm to a point midway
adequately perfuse the hand in isolation. The test is then repeated with
between the ulnar head and the dorsal radial tubercle. The superficial
release of digital pressure on the other artery.
radial nerve passes inferiorly, deep to brachioradialis, and becomes
superficial passing between brachioradialis and extensor carpi radialis
Veins
longus, approximately 8.5 cm proximal to the radial styloid process
(Auerbach et al 1994, Park et al 2010). Its terminal branches are palpa
The superficial veins of the upper limb are usually visible and palpable, ble as they pass over the tendon of extensor pollicis longus where it
especially when a tourniquet occludes venous return proximally. At the borders the anatomical snuffbox.


PECTOral GIrdlE aNd UPPEr lImb: OvErvIEw aNd SUrfaCE aNaTOmy
792
6
NOITCES
A B A Anterior B Posterior
C3 C3
C4
C4
C5
T2
T2
C5 Supraclavicular, C3, 4
Upper lateral cutaneous of arm, C5, 6
Posterior cutaneous of arm, C5, 6, 7, 8
Intercostobrachial, T2
T1
Medial cutaneous of arm, C8, T1
T1
Lower lateral cutaneous of arm, C5, 6
C6 Posterior cutaneous of forearm, C5, 6, 7, 8
C6
Medial cutaneous of forearm, C8, T1
Lateral cutaneous of forearm, C5, 6
Superficial branch of radial, C7, 8
C8 C8 Ulnar, C8,T1
C7
C7 Median, C6, 7, 8
Ventral axial line Dorsal axial line
Fig . 46 .31 The dermatomes of the left upper limb . Overlap across the
axial lines is minimal, whereas overlap is considerable across the
interrupted lines . A, Viewed from the anterior aspect . B, Viewed from the
Fig . 46 .32 The distribution of skin territories supplied by the cutaneous
posterior aspect . (Adapted from Drake RL, Vogl AW, Mitchell A (eds),
nerves of the left upper limb . A, Viewed from the anterior aspect .
Gray’s Anatomy for Students, 2nd ed, Elsevier, Churchill Livingstone .
B, Viewed from the posterior aspect .
Copyright 2010 .)
The median nerve is intimately related to the brachial artery through Triceps jerk (C6–8) The arm is supported at the wrist and flexed to
out its course in the arm. In the forearm, it passes along a line joining a right angle. Triceps tendon is struck with a percussion hammer just
a point just medial to the pulsating brachial artery in the cubital fossa proximal to the olecranon; this should elicit extension of the elbow.


to the tendon of palmaris longus, or to a point just lateral to the tendon
at the wrist (see Fig. 46.29B). Radial jerk (C7, 8) The radial jerk is a periosteal, not a tendon, reflex.
The ulnar nerve passes posterior to the medial epicondyle and can The elbow is flexed to a right angle and the forearm placed in the mid
be rolled from side to side just proximal to the epicondyle (see Fig. pronation/supination position. The radial styloid is struck with the
46.29B). In the forearm and proximal hand, its course corresponds to percussion hammer. This elicits contraction of brachioradialis, which
a line drawn from the base of the posterior aspect of the medial epi causes flexion of the elbow.
condyle of the humerus to the lateral side of the pisiform, where it
Nerve blocks
passes through Guyon’s canal and across the hook of the hamate. Deep
pressure at these bony landmarks can produce paraesthesia in the dis Brachial plexus There are three common approaches to achieve
tribution of the nerve. Proximally, the nerve sits deep to flexor carpi anaesthetic blockade of the brachial plexus: the interscalene, supra
ulnaris; distally, it sits lateral to the tendon of flexor carpi ulnaris and clavicular and axillary routes.
medial to the ulnar artery and its venae comitantes. The interscalene route requires identification of the interscalene
groove. The patient is asked to sniff, an action that involves the scalene
Dermatomes muscles as accessory muscles of respiration. A needle is inserted per
Knowledge of the extent of individual dermatomes is largely based on pendicular to the skin and enters the interscalene groove. Paraesthesia
clinical evidence. The dermatomes of the upper limb arise from spinal may be elicited, and local anaesthetic solution is injected. There is a
nerves C5–8 and T1; C7 supplies the central part of the hand (Figs risk that some local anaesthetic may move in a retrograde direction and
46.31–46.32). Considerable overlap exists between adjacent der reach the cervical epidural space. The proximal nature of the block


matomes innervated by nerves derived from consecutive spinal cord means that there is almost always some involvement of the phrenic
segments. nerve, and sympathetic block (as evidenced by a Horner’s syndrome) is
universal.
Myotomes The supraclavicular route places local anaesthetic solution in the
The predominant segmental origin of the nerve supply for each of the plane occupied by the trunks of the brachial plexus as they emerge
muscles of the upper limb and for the movements that take place at the between scalenus anterior and medius on the first rib, immediately
joints of the upper limb are summarized in Tables 46.1–46.4. posterior to the third part of the subclavian artery. The site of injection
is 2 cm above the midpoint of the clavicle. The needle is directed back
Reflexes
wards, inwards and downwards to make contact with the upper surface
Biceps jerk (C5, 6) The elbow is flexed to a right angle and slightly of the first rib. During this procedure, the patient will usually complain
pronated. A finger is placed on the biceps tendon and struck with a of paraesthesia down the arm, which indicates that the needle is cor
percussion hammer; this should elicit flexion and slight supination of rectly placed; preliminary aspiration ensures that a major vessel has not
the forearm. been punctured. If the first rib is missed, there is the risk of producing


Surface anatomy
793
64
rETPaHC
a pneumothorax. There is often a transient Horner’s syndrome, caused dorsoradial border of the wrist, where branches of the nerve can be
by diffusion of the local anaesthetic towards the stellate ganglion. rolled over the tendon of extensor pollicis longus (see Fig. 46.30C).
The axillary approach blocks the nerves as they group around the
axillary artery. digital nerves
The digital nerves lie on either side of the flexor sheath in a plane
Wrist Useful anaesthesia of the palm of the hand (except for the lateral immediately anterior to the phalanx (see Fig. 46.30A). Therefore, the
surface of the thumb base) can be achieved by blockade of the ulnar needle should be inserted on either side of the base of the digit, just
and median nerves at the wrist (see Video 50.2). The ulnar nerve may anterior to the anterolateral margin of the phalanx. A common alterna
be blocked via a needle inserted lateral to the tendon of flexor carpi tive approach to blocking the digital nerves is via a dorsal skin approach;
ulnaris at the wrist. The median nerve may be blocked via a needle the needle is inserted through the dorsal skin on either side of the base
inserted at the midline between the tendons of palmaris longus and of the proximal phalanx and advanced towards the volar location of
flexor carpi radialis at the level of the proximal wrist crease. the digital nerves while the local anaesthetic agent is continually
The radial nerve, which supplies the dorsal skin of the hand, may infused. This is thought to be less painful than the volar approach
be blocked by injecting local anaesthetic around the subcutaneous because the dorsal skin is less sensitive than the volar skin.
Bonus e-book images, tables and video
Fig . 46 .17 The area of sensory abnormality Fig . 46 .23 A–B, Transection of the median Fig . 46 .28 Sympathetic paralysis seen within
after transection of C8 and T1 . nerve, ulnar nerve, medial cutaneous nerve a few days of transection .
of the forearm, and brachial artery, in the


Fig . 46 .18 The area of sensory arm of a 14-year-old boy . Table 46 .1 Movements, muscles and
abnormality after section of the lateral segmental innervation in the upper limb .
cord in the axilla . Fig . 46 .24 A high median nerve injury; there is
no active flexion of the index finger and thumb . Table 46 .2 Segmental innervation of the
Fig . 46 .19 Rupture of the posterior divisions muscles of the upper limb .
of the trunks of the brachial plexus deep to Fig . 46 .25 Section of the median nerve and
the clavicle . the palmar cutaneous nerve at the wrist . Table 46 .3 Segmental innervation of joint
movements of the upper limb .
Fig . 46 .20 Rupture of the axillary nerve . Fig . 46 .26 A–B, A typical area of loss of
sensibility after division of the nerve at the Table 46 .4 Movements and muscles tested
Fig . 46 .21 Sensory loss in two cases of wrist, sparing the palmar cutaneous branch . to determine the location of a lesion in the
rupture of the musculocutaneous nerve . upper limb .
Fig . 46 .27 The area of sensory loss and
Fig . 46 .22 A–B, Two examples of high ‘clawing’ of little and ring fingers after Video 46 .1 Upper limb surface anatomy .
lesion of the radial nerve . division of the ulnar nerve in the forearm . Clinical examination of muscles in the limbs .


Pectoral girdle and upper limb: overview and surface anatomy
793.e1
64
rETPaHC
REFERENCES
Auerbach DM, Collins ED, Kunkle KL et al 1994 The radial sensory nerve: Ladak A, Tubbs RS, Spinner RJ 2014 Mapping sensory nerve communica
an anatomic study. Clin Orthop Relat Res 308:241–9. tions between peripheral nerve territories. Clin Anat 27:681–90.
Bono CM, Grossman MG, Hochwald N et al 2000 Radial and axillary nerves: Park BK, Bun HR, Hwang M et al 2010 Medial and lateral branches of the
anatomic considerations for humeral fixation. Clin Orthop Relat Res superficial radial nerve: cadaver and nerve conduction studies. Clin
373:259–64. Neurophysiol 121:228–32.
Camp SJ, Birch R 2011 Injuries to the spinal accessory nerve: a lesson to Seddon HJ 1975 Surgical Disorders of the Peripheral Nerves, 2nd ed. Edin
surgeons. J Bone Joint Surg Br 93:62–7. burgh: Churchill Livingstone, p. 177.
Cetik O, Uslu M, Acar HI et al 2006 Is there a safe area for the axillary nerve Stenning M, Drew S, Birch R 2005 Lowenergy arterial injury at the shoulder
in the deltoid muscle? A cadaveric study. J Bone Joint Surg Am 88: with progressive or delayed nerve palsy. J Bone Joint Surg Br 87:
2395–9. 1102–6.
Cho H, Lee HY, Gil YC et al 2013 Topographical anatomy of the radial nerve Wilbourn AJ 2005 Brachial plexus injuries. In: Dyck PJ, Thomas PK (eds)
and its muscular branches related to surface landmarks. Clin Anat 26: Peripheral Neuropathy, 4th ed. Philadelphia: Elsevier, Saunders; Ch. 55,
862–9. pp. 1339–73.
Copeland SA, Howard RC 1978 Thoracoscapular fusion for fascioscapulo Wynn Parry CB 1981 Rehabilitation of the Hand, 4th ed. London:
humeral dystrophy. J Bone Joint Surg Br 60B:547–51. Butterworth.


Cox CL, Riherd D, Tubbs RS et al 2010 Predicting radial nerve location using
palpable landmarks. Clin Anat 23:420–6.


CHAPTER Development of the pectoral girdle and
47
upper limb
elongated and is opposite the developing ventricles of the heart; it is
PECTORAL GIRDLE DEVELOPMENT
directed caudally because of preferential elongation of the preaxial part
of the bud. At stage 15, the upper limb can be subdivided into definite
The pectoral girdle develops at an interface between the tissues forming regions. The proximal portion, still showing the dorsal bulge and
the head and neck, the back and the upper limb. Each of these regions ventral curve, is the shoulder and upper arm region; the next distal
appears to have different cell lineages and genes contributing to the portion can now be identified as the forearm; the most distal portion
development of similar tissues. Studies on the development of the avian is now expanded into a flattened hand plate.
scapula, also confirmed in the mouse, show that lateral scapular struc- At stage 16, there are the first indications of digit rays in the hand
tures derive from the somatopleuric mesenchyme, whereas the medial plate. The limb may be close to the body wall or may be abducted. By
border of the scapula and the attachment sites for the rhomboid stage 17, the upper limb has an elbow region and well-defined digit
muscles originate from dermomyotomes of somites: specifically, the rays; the hand plate may show a crenated rim, indicating the start of
hypaxial domain (Wang et al 2005, Valasek et al 2010, Valasek et al tissue removal between the digits (see Fig. 15.1). Crenation of the hand
2011). The connective tissues of those muscles and their attachment plate between the digit rays continues in stage 18 embryos (44 days).
sites on the pectoral girdle innervated by the accessory nerve are derived Changes during stages 19–23 are concerned with growth of the limb
from neural crest (Matsuoka et al 2005). and separation of the digits. The hands now curve over the cardiac
Early limb development is patterned by somatopleuric mesenchyme, region. The distal phalangeal portions of the fingers enlarge at stage 21,


within a permissive interaction with the limb ectoderm. Upper limb forming the nail beds. For more details, see O’Rahilly and Gardner
myoblasts migrate laterally from the ventrolateral border of cervical (1975), Gupta et al (2000).
dermomyotomes and form dorsal and ventral masses prior to migration Most of the bones in the appendicular skeleton are derived from
into the limb bud. After a brief period within the limb bud, a subset of somatopleuric mesenchyme. Within the upper limb, although the clavi-
the myoblasts migrate medially out of the limb bud and into the axial cle and coracoid portion of the scapula arise from somatopleuric mes-
mesenchyme to form the pectoral muscles ventrally and latissimus dorsi enchyme, studies in both avian and mouse embryos have shown that
dorsally. This origin of superficial pectoral girdle muscles has been the distal third of the blade of the scapula is derived from the somites
described as an ‘in–out’ mechanism (Valasek et al 2011), and refers to (Shearman et al 2011, Valasek et al 2010). Prechondroblasts are present
the initial migration into the limb bud and the subsequent migration in the upper limb at stage 13, and condensations of cartilage can be
back towards axial structures. Only myoblasts undergo this second, detected at stage 16, when the humeral anlage can be recognized. Cavi-
medial, migration out of the limb bud; the somatopleuric mesenchyme tation of the shoulder and elbow joints occurs at 7–8 weeks. By stage
remains within the proximal limb anlagen and produces the gleno- 17, when the radius and ulna chondrify, the branched tips of the radial,
humeral joint and coracoid process. median and ulnar nerves have migrated to the distal hand plate. The
Some myoblasts, originating from the ventrolateral edges of cervical carpals chondrify at stage 18, when the hand plate shows notching of
dermomyotomes and extending as the hypaxial domain of the somite, the digital rays.
switch off their myogenic fate and follow a cartilage lineage to form the


medial part of the scapula. The remaining hypaxial domain myoblasts
form serratus anterior, and the rhomboid muscles, deep pectoral girdle VESSELS
muscles, attach to this medial part (Valasek et al 2011).
Trapezius and sternocleidomastoid, innervated by the accessory Arteries
nerve, are derived from the upper occipital somites (see Fig. 36.7); they
migrate into neural crest mesenchyme, which forms their connective In the upper limb, usually only one arterial trunk, the subclavian, per-
tissue. The proximal and distal attachments of trapezius, to the nuchal sists; it probably represents the lateral branch of the seventh interseg-
line of the occipital bone and the upper part of the spine of the scapula, mental artery. Its main continuation, the axial artery of the upper limb,
respectively, are derived from post-otic neural crest cells (Matsuoka et al becomes the axillary and brachial arteries, passes into the forearm deep
2005). The attachment of sternocleidomastoid to the clavicle also dem- to the flexor muscle mass and terminates as a deep plexus in the devel-
onstrates its dual origin from neural crest cells and somatopleuric mes- oping hand (Fig. 47.1). The original axial vessel ultimately persists as
enchyme. The sternum is derived from somatopleuric mesenchyme, the anterior interosseous artery and the deep palmar arch. A branch
although there is evidence of neural crest within the manubrium. from the main trunk passes dorsally between the early radius and ulna
The ‘muscle scaffold model’ proposed by Matsuoka et al (2005), as the posterior interosseous artery; a second branch accompanies the
where muscle connective tissue and muscle attachment sites illustrate median nerve into the hand, where it ends in a superficial capillary
the origin of the mesenchymal cells patterning their development, plexus. The radial and ulnar arteries are the latest arteries to appear in
may explain a range of anomalies based on defects of post-otic neural the forearm. Initially, the radial artery arises more proximally than the


crest and which affect the pharynx and larynx as well as the shoulder ulnar artery, crosses anterior to the median nerve, and supplies biceps
region, e.g. Klippel–Feil disease, Sprengel’s deformity and cleidocranial brachii. Later, the radial artery establishes a new connection with the
dysplasia. main trunk at or near the level of origin of the ulnar artery, and the
upper portion of its original stem usually disappears. On reaching
the hand, the ulnar artery links up with the superficial palmar plexus,
UPPER LIMB DEVELOPMENT
from which the superficial palmar arch is derived. The median artery
commonly loses its distal connections and is reduced to a small vessel.
The upper limb bud is first visible as a thickening along the lateral The radial artery passes to the dorsal surface of the hand, gives off dorsal
longitudinal axis of the body wall opposite somites 8–10, at the level digital branches, traverses the first intermetacarpal space and joins the
of the entrance to the cranial intestinal portal during stage 12. It deep palmar arch.
enlarges, protruding laterally from its elliptical base at the body wall as Anomalies of the arterial tree in the forelimb are fairly common:
a symmetrical bud, with a curved border and an apical ectodermal ridge there are several potential causes. The arteries have multiple and plexi-
forming its distal tip. Initially, it has equal and relatively flat dorsal and form sources; the principal arteries, anastomoses and periarticular
ventral ectodermal surfaces and a somatopleuric mesenchymal core. By networks emerge according to a temporal sequence; and some paths
794 stage 13, the upper limb bud is curved ventrally. By stage 14, it has that are initially functionally dominant subsequently regress. In general,


Neonatal upper limb
795
74
RETPAHC
Primary axial
Subclavian
Stage 13
Axiliary
Circumflex humeral
Brachial
Interosseous Profunda brachii
Ulnar
Brachial
Median
Stage 16
Ulnar collateral Radial recurrent
Brachial
Interosseous
Interosseous
Deep palmar arch
Radial
Median
Radial Ulnar
Ulnar
Median
Stage 18 Superficial palmar arch
Fig. 47.1 Stages in the development of the arteries of the arm. The path of the axial artery is indicated by an interrupted line.
anomalous patterns may present as differences in the mode and proxi- but much more developed. When the proportions of parts of the upper
modistal level of branching; the presence of unusual compound arterial limb are examined, the forearm is longer than the arm in the newborn,
segments; aberrant vessels that connect with other principal vessels, and more so in boys than girls. Only primary centres of ossification are
arcades or plexuses; vessels that occupy exceptional tissue planes (e.g. present in the upper limb, apart from a centre in the head of the
superficial fascia instead of the usual subfascial route), or vessels that humerus. The elbow of the newborn can flex to 145° but lacks some
have unexpected neural, myological or osteoligamentous relationships. 10–15% of full extension. The neonate has a relatively strong grasp
within the first few days. The fingernails usually extend to the fingertips
Veins or just beyond. They are soft at birth but soon dry and become quite
firm and sharp.
In the upper limb, the preaxial vein becomes the cephalic vein and
Peripheral arterial puncture in the neonate
drains into the axillary vein at the shoulder. The postaxial vein becomes
the basilic vein, which passes deep in the arm to continue as the axillary It is common practice to insert a small-bore cannula into a peripheral
vein. artery in neonates receiving intensive care when either the umbilical
artery is not accessible or there are clinical reasons to avoid cannulation
of the umbilical vessels. Trans-illumination can be used to provide an


ULTRASOUND ANTENATAL IMAGING outline of the artery to be cannulated. The peripheral arteries that are
most commonly used are the radial artery, just above the anterior
In the routine 18–20-week ultrasound fetal assessment, shortening of surface of the wrist, and the posterior tibial artery, posterior to the
long bones below 2 standard deviations should lead to a full assessment medial malleolus. The proximity of the ulnar nerve to the ulnar artery
of all bones (McHugo 2007). Whereas the majority of lethal short limb increases the risk of nerve damage associated with arterial cannulation
dysplasias show marked shortening by this time, non-lethal short limb of the ulnar artery, and the relatively poor collateral circulation associ-
dysplasias seen at birth are not apparent at 20 weeks’ gestation. Nor- ated with the dorsalis pedis artery means that this artery is used only
mally, the humerus should be slightly longer than the radius and ulna. as a last resort. The brachial artery at the antecubital fossa also has a
The term rhizomelia is used where limb shortening affects the proximal poor collateral circulation and the median nerve is in close proximity;
bones more than the distal bones. it is generally considered, therefore, that cannulation of this artery is
not justified.
Confirmation that an adequate collateral circulation is present when
NEONATAL UPPER LIMB
cannulating the radial artery can be obtained by performing Allen’s test,
in which both the radial and ulnar arteries are compressed at the wrist
In general, the upper limbs in the neonate are proportionately shorter after exsanguination of the hand; release of pressure on the ulnar artery
than they are in the adult. They are long compared with the neonatal while maintaining occlusion of the radial artery should result in reper-
trunk and lower limbs, and extend to the upper thigh as they do in the fusion of the hand if an adequate collateral ulnar arterial supply is
adult, but the trunk is much shorter in the neonate (see Fig. 14.8). At present. Alternatively, intact arterial flow can usually be confirmed,
birth, the upper limbs are about the same length as the lower limbs, particularly in the preterm infant, by direct visualization of the arteries


DEvEloPmENT of THE PECToRAl giRDlE AND uPPER limb
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using trans-illumination. A cold light source is placed on the posterior segments still formed. There is evidence from experiments in chick
aspect of the lower forearm and the shadow of the pulsating arteries embryos that thalidomide interferes with vascularization of the limbs
can be seen on the anterior surface of the forearm. (Vargesson 2009), and this could lead to mesenchymal cell death.
Recent work has identified a protein to which thalidomide binds and
could eventually lead to uncovering molecular mechanisms of thalido-
DEVELOPMENTAL ANOMALIES OF
mide teratogenicity (Ito et al 2010).
THE UPPER LIMB Inheritance of autosomal dominant genes may cause anomalies of
the hand. This could, for example, result in absence of the central digit
Approximately 1 in 600 neonates will have a congenital anomaly of the ray of the distal hand plate and subsequent absence of the middle or
hand or forearm, 30% of which will be bilateral. They occur with an ring finger and its metacarpals. Extra preaxial digits can result from
approximately equal frequency in males and females. A defect is twice ectopic polarizing activity due to mutations in regulatory regions that
as likely to occur in the upper limb as in the lower limb. The most criti- control expression of the Shh gene, specifically in the developing limb
cal period for the development of anomalies is during stages 12–16. bud (Anderson et al 2012). Other changes in digit number may be the
One classification of congenital limb malformation uses seven sub- result of alterations in limb bud width and the length of the apical
groups (Swanson 1976). These describe a clinical picture and do not ectodermal ridge.
always relate accurately to the developmental process occurring in the
limb. The first subgroup is failure of formation of parts of a limb. The
second subgroup, failure of differentiation, includes unsuccessful sepa- ANOMALIES OF THE DIGITS
ration of parts, and so includes the range of syndactylies. Groups three
to five include limb duplication, overgrowth and undergrowth. Group Webbing of the fingers is the most common congenital anomaly of the


six includes limb amputations, mainly by adherent amniotic bands, and hand. It occurs because of failure to remove cells between the digit rays
the last group includes all other generalized skeletal anomalies. A more during stages 19–23. Clinodactyly is a congenital condition in which
recent classification of upper limb anomalies, based on developmental the little finger is curved towards the ring finger. It can occur in isolation,
molecular biology and pathogenetics, clearly defines all terms used to or in association with chromosomal abnormalities like Down’s syn-
describe anomalous structure and provides a comprehensive and con- drome. Camptodactyly is a congenital condition in which the little
sistent terminology for the range of anomalies (Oberg et al 2010, finger, and sometimes the ring finger, are held in a fixed, flexed position.
Tonkin et al 2013, Goldfarb 2015). Symphalangism is a rare congenital disorder in which there is fusion
of the interphalangeal joints. The affected finger is stiff, skin creases are
absent over the affected joint, there is minimal joint space, and some-
LIMB REDUCTION DEFECTS times the digit is shorter than normal. Several different types of brachy-
dactyly, shortening of the digits, can be recognized according to which
Limb reduction defects are categorized as failures of development. The digits and which parts of these digits are affected. The genetic basis of
basis of limb reductions seen in infants whose mothers took thalido- different types of brachydactyly has now been determined, which is
mide during their pregnancy seems likely to be due to death of mesen- particularly gratifying because brachydactyly was the first condition in
chyme cells in the early limb bud, causing phocomelia. Proximal humans to be recognized as a dominant Mendelian condition (Gao and
segments of the limb were lost, although, in some cases, normal distal He 2004).
KEY REFERENCES
Gupta A, Kay SPJ, Scheker LR 2000 The Growing Hand. London: Harcourt. Tonkin MA, Tolerton SK, Quick TJ et al 2013 Classification of congenital
A source that includes articles on embryology, growth and congenital anomalies of the hand and upper limb: development and assessment
anomalies of the hand. of a new system. J Hand Surg Am 38:1845–53.


Presents the Oberg, Manske and Tonkin (OMT) classification of upper limb
Matsuoka T, Ahlberg PE, Kessaris N et al 2005 Neural crest origins of the anomalies and the challenges of incorporating the molecular mechanisms of
neck and shoulder. Nature 436:347–55. limb anomalies into current systems.
This paper considers the development of the transition zones between the
head and neck, the back and the pectoral girdle. Valasek P, Theis S, Krejci E et al 2010 Somitic origin of the medial border of
the mammalian scapula and its homology to the avian scapula blade.
O’Rahilly R, Gardner E 1975 The timing and sequence of events in the J Anat 216:482–8.
development of the limbs in the human embryo. Anat Embryol 148: Establishes the avian scapular blade and medial border of the mammalian
1–23. scapula as homologous structures that share the same developmental origin.
A description of the stages in human limb development.
Valasek P, Theis S, DeLaureir A et al 2011 Cellular and molecular investiga-
Swanson AB 1976 A classification for congenital limb malformations. tions into the development of the pectoral girdle. Dev Biol 357:
J Hand Surg Am 1:8–22. 108–16.
A source that sets out details of an accepted classification for congenital Provides evidence that the formation of the muscles of the proximal limb
limb malformations. occurs through two distinct mechanisms.


Development of the pectoral girdle and upper limb
796.e1
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RETPAHC
REFERENCES
Anderson E, Peluso S, Lettice LA et al 2012 Human limb abnormalities Shearman RM, Tulenko FJ, Burke AC 2011 3D reconstructions of quail-chick
caused by the disruption of hedgehog signalling. Trends Genet 28: chimeras provide a new fate map of the avian scapula. Dev Biol 355:
364–73. 1–11.
Gao B, He L 2004 Answering a century old riddle: brachydactyly type A1. Swanson AB 1976 A classification for congenital limb malformations.
Cell Res 14:179–87. J Hand Surg Am 1:8–22.
Goldfarb CA, Wall LB, Bohn DC et al 2015 Epidemiology of congenital A source that sets out details of an accepted classification for congenital
upper limb anomalies in a midwest United States population: an assess- limb malformations.
ment using the Oberg, Manske, and Tonkin classification. J Hand Surg Tonkin MA, Tolerton SK, Quick TJ et al 2013 Classification of congenital
Am 40:127–32. anomalies of the hand and upper limb: development and assessment
Gupta A, Kay SPJ, Scheker LR 2000 The Growing Hand. London: Harcourt. of a new system. J Hand Surg Am 38:1845–53.
A source that includes articles on embryology, growth and congenital Presents the Oberg, Manske and Tonkin (OMT) classification of upper limb
anomalies of the hand. anomalies and the challenges of incorporating the molecular mechanisms of
limb anomalies into current systems.
Ito T, Ando H, Suzuki T et al 2010 Identification of a primary target of tha-
lidomide teratogenicity. Science 327:1345–50. Valasek P, Theis S, Krejci E et al 2010 Somitic origin of the medial border of
Matsuoka T, Ahlberg PE, Kessaris N et al 2005 Neural crest origins of the the mammalian scapula and its homology to the avian scapula blade.
neck and shoulder. Nature 436:347–55. J Anat 216:482–8.


This paper considers the development of the transition zones between the Establishes the avian scapular blade and medial border of the mammalian
head and neck, the back and the pectoral girdle. scapula as homologous structures that share the same developmental origin.
McHugo JM 2007 Skeletal anomalies. In: Twining P, McHugo JM, Pilling Valasek P, Theis S, DeLaureir A et al 2011 Cellular and molecular investiga-
DW (eds) Textbook of Fetal Abnormalities, 2nd ed. Edinburgh: Elsevier, tions into the development of the pectoral girdle. Dev Biol 357:
Churchill Livingstone; Ch. 12. 108–16.
Provides evidence that the formation of the muscles of the proximal limb
Oberg KC, Feenstra JM, Manske PR et al 2010 Developmental biology and
occurs through two distinct mechanisms.
classification of congenital anomalies of the hand and upper extremity.
J Hand Surg 35:2066–76. Vargesson N 2009 Thalidomide-induced limb defects: resolving a 50-year-
O’Rahilly R, Gardner E 1975 The timing and sequence of events in the old puzzle. Bioessays 31:1327–36.
development of the limbs in the human embryo. Anat Embryol 148: Wang B, He L, Ehehalt F et al 2005 The formation of the avian scapular
1–23. blade takes place in the hypaxial domain of the somites and requires
A description of the stages in human limb development. somatopleure-derived BMP signals. Dev Biol 287:11–18.


CHAPTER
48
Shoulder girdle and arm
The upper limb is differentiated to achieve complex patterns of stereo that passes superiorly towards the acromion and pierces the edge of
tactic, nonstereotactic and gestural movements (each with a distinct deltoid and the deep fascia to fan out and supply the overlying skin.
neurological basis) that enable hand function. The combined motion The medial side of the upper arm is supplied by five or six fascio
of the shoulder and elbow brings objects in the hand into the visual cutaneous perforators that arise from the brachial artery, the superior
field, while the great range of the shoulder and pectoral girdle enable ulnar collateral artery and, if present, the single artery to biceps brachii.
reaching into a wide external environment. Oculospinal afferents These perforators pass along the medial intermuscular septum to spread
appear to be the most important modulators of shoulder joint stability out in the deep fascia and anastomose with perforating vessels superi
necessary for reaching. An object is first reached and then grasped orly and inferiorly, and from the lateral side. There are virtually no
(increasing both superficial and deep peripheral afferent inputs that musculocutaneous perforators through biceps or triceps.
enhance proximal shoulder girdle stability (Alizadehkhaiyat et al The lateral side of the upper arm below deltoid is supplied by per
2011)), before being retrieved into the visual field. The requirements of forating vessels from the middle collateral and radial collateral arteries
attention to the visual field define the need for stability in the shoulder (the terminating bifurcation of the profunda brachii). The middle col
girdle: the closer the attention to an object in the centre of the field of lateral artery sends perforators to the skin via the lateral intermuscular
vision (‘macular vision’), the finer is the control of the motion and septum between brachioradialis and triceps, while the radial collateral
stability of the shoulder girdle. artery gives off cutaneous perforators via the intermuscular septum
The joints of the upper limb become more complex proximodistally. between brachialis and brachioradialis. These cutaneous vessels anas


The greatest potential for stability is gained through ‘closepacking’ (the tomose with those from the medial side.
state of a joint where the greatest stability is achieved for the least
energy) in the carpus of the hand, while the range of available motion Cutaneous innervation
in each joint becomes more restricted. Closepacking occurs through a
lesser, more specific, range of motion in the elbow; the flexed elbow
The skin over the anterior shoulder region is mobile and accommodates
with a supinated forearm is the position for carrying the greatest load
the great mobility of the shoulder girdle. The skin over the posterior
with the least energy expenditure or the greatest resistance to fatigue.
aspect of the shoulder girdle is thicker and less mobile, being held to
Closepacking occurs in the glenohumeral joint, so providing for stabil
the underlying scapula by coarse connective tissue fibres. The cutaneous
ity, but it is almost entirely gained through muscular activity; at the
innervation reflects this difference in skin quality; the supraclavicular
extremes of range, through capsular fibre spiralling, it is costly in terms
nerves (see Fig. 29.1) are long, mobile nerves passing deep to platysma
of muscular energy expenditure, especially on a background of age and
before piercing the muscle and the investing cervical fascia over or
genedependent musculotendinous degeneration. The least intrinsically
immediately caudal to the clavicle. The medial clavicular skin, including
stable joint in the body, the scapulothoracic, is entirely dependent on
the skin over the sternoclavicular joint, is innervated by the small, often
muscular activity for stable position and motion around the fulcrum of
multifilamentous, medial supraclavicular nerve. The skin over the clavi
the acromioclavicular joint.
cle and over a variable extent of the anterior chest skin, including a
For the purposes of this chapter, the junction between the ‘arm’ and
variable extent of the anterior axillary fold, is innervated by the large,
the ‘elbow joint’ will be taken to be the level at which the radial nerve
perforates the lateral intermuscular septum to enter the anterior com
partment of the arm, and the ulnar nerve perforates the medial inter


muscular septum to gain the posterior compartment of the arm at the A B
elbow.
SKIN AND SOFT TISSUES C4–T1
C4–T1
SKIN
Cutaneous vascular supply
C5–T1
The skin over the lateral end of the clavicle is supplied by the supracla
C5–T1
vicular artery, which pierces the deep fascia superior to the clavicle and
anterior to trapezius. In the majority of cases, this artery arises from the
superficial cervical/transverse cervical artery, but it occasionally arises
from the suprascapular artery. The area over deltoid is supplied by the
anterior and posterior circumflex humeral arteries. The deltoid branch
of the thoracoacromial axis contributes to the blood supply of the
anterior aspect of the shoulder via musculocutaneous perforators
through deltoid.
The blood supply to the skin of the upper arm may be divided into
three regions with separate supplies. The deltoid region is supplied by
musculocutaneous perforators, and the medial and lateral regions are
supplied by fasciocutaneous perforators (Cormack and Lamberty 1994;
Salmon, in Taylor and Razaboni 1994).
The deltoid region is supplied by the posterior circumflex humeral
artery via musculocutaneous perforators. After exiting from the quad Fig. 48.1 The approximate area of sensory loss or disturbance after
rangular space, it gives off a descending branch that runs down to the proven preganglionic (avulsion) lesion of C4–T1 and C5–T1. A, Anterior
insertion of deltoid and the overlying skin, and an ascending branch view. B, Posterior view. 797


Shoulder girdle and arm
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noiTCeS
A B A B
Axillary nerve
C5
Medial cord
Medial cord
Fig. 48.4 The approximate area of sensory loss or disturbance after
Fig. 48.2 The approximate area of sensory loss or disturbance after
complete interruption of the medial cord. A, Anterior view. B, Posterior
complete interruption of C5 and the axillary nerve. A, Anterior view.
view.
B, Posterior view. Sensory loss is greater in C5 lesions than in axillary
lesions.
Fig. 48.5 The approximate
area of sensory loss or
disturbance after complete
A B interruption of the posterior
cord. Posterior view.
Lateral cord
Lateral cord
Fig. 48.3 The approximate area of sensory loss or disturbance after
complete interruption of the lateral cord. A, Anterior view. B, Posterior
view. Sometimes, loss of sensation is not complete; this is also true of
the medial cord.
the radial nerve). Figures 48.1–48.5 illustrate the approximate areas of
sensory loss or disturbance after pre or postganglionic lesions involv
ing C4T1.
middle supraclavicular nerve. This nerve is frequently injured by injudi
SOFT TISSUES
cious incisions for the surgical treatment of fractures of the clavicle; a
painful neuroma is a common outcome. The skin over the lateral clavi
Deep fascia
cle, acromion and deltoid region is innervated by the lateral supracla
vicular nerve or nerves. The floor of the axilla, together with part of the
upper medial aspect of the arm, is supplied by the intercostobrachial In common with locomotor muscles in the lower limb, the upper limb
nerve (lateral branch of the second intercostal nerve). Occasionally, the muscles are attached, in varying degrees, to their surrounding deep
lateral branch of the third intercostal nerve contributes to the supply of fascial envelopes. This arrangement increases the area (footprint) of
the skin in the floor of the axilla. The lower aspect of the medial side attachment of a muscle within a fascial compartment, so increasing


of the upper arm is supplied by the medial cutaneous nerve of the arm. the effectiveness and efficiency of that muscle. For example, the fasciae
The lateral aspect of the upper arm is supplied by the upper lateral overlying the three muscles of the scapular fossae (subscapularis, infra
cutaneous nerve (a branch of the axillary nerve) and the lower lateral spinatus and supraspinatus) are well attached and thicker medially;
cutaneous nerve (a branch of the radial nerve). The posterior aspect is the fibroosseous cuff so formed around the medial parts of the
supplied by the posterior cutaneous nerve of the arm (a branch of muscles affords a greater area of attachment than would be available if


Bones
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the muscles were attached only to the scapular fossae. The blood Infraspinous fascia
supply to the muscles of the upper limb is defined by their fascial The infraspinous fascia covers infraspinatus and is attached to the
compartmentation. margins of the infraspinous fossa, except cranially and medially, where
there is a loose attachment to the lower aspect of the spine of the
Compartment syndrome of the arm The muscular compart scapula. Cranially and laterally, the infraspinatus fascia is continuous
ments of the arm (and thigh) are not so well defined as those of the with the supraspinatus fascia, creating a single muscular compartment
forearm (and leg). Compartment syndrome is not so common in for the two muscles. The deep fibres of deltoid are attached to the
trauma of the arm but remains a concern, particularly after extensive infraspinatus fascia over a strip of about 1 cm for the entire length of
reconstruction procedures and highenergy or crushing injuries of the the spine of the scapula; the examining finger cannot palpate the spine
limb. of the scapula from within the space between deltoid and infraspinatus.
The fascia is contiguous with the strong lower border of the deltoid
Fascia over deltoid
fascia along the overlapping posterior border of deltoid.
The deep fascia over deltoid is thickest anteriorly and posteriorly, and
Supraspinous fascia
is adherent in a linear fashion to the external aspect of the superficial
fibrous septa of the central (lateral) part of that muscle. It blends with The supraspinous fascia completes the osseofibrous compartment con
the pectoral fascia in front, and with the thick and strong fascia overly taining supraspinatus; it is attached to the scapula around the bound
ing infraspinatus behind. Above, it blends with the periosteum of the aries of the attachment of supraspinatus. It is thick medially, where
lateral part of the clavicle, the thin periosteum of the acromion, the supraspinatus attaches to its own fascia, but thinner laterally under the


crest of the scapular spine and the cranial part of the medial border of coracoacromial ligament.
the scapula, caudal to the spine of the scapula, where it blends with the
Brachial fascia
infraspinatus fascia. Below, it is continuous with the deep brachial
fascia, blending with the lateral intermuscular septum (Leijnse et al The deep fascia of the upper arm, the brachial fascia, is continuous with
2008). the fasciae covering deltoid and pectoralis major; it forms a thin, loose
covering for the anterior muscles of the arm and a more robust covering
Pectoral and axillary fascia
for the posterior muscles. Medially, just below the middle of the upper
The pectoral fascia is thin over pectoralis major. It is attached medially arm, it is perforated by the basilic vein, lymphatic vessels and, at various
to the sternum and is continuous with the fascia of the rectus sheath levels, by branches of the brachial cutaneous nerves.
caudally. Cranially, it blends with the periosteum of the clavicle and the The fascia is thickest distally, where it contains the brachial muscles
anterior aspect of the capsule of the sternoclavicular joint. Laterally, it in distinct compartments, anteriorly and posteriorly, and defined medi
is continuous with the fascia over deltoid; it forms the roof of the infra ally and laterally by tough septa. The lateral intermuscular septum is
clavicular fossa between the muscular attachments of pectoralis major continuous with the fascia overlying the lateral part of deltoid proxi
and deltoid to the clavicle. The fascia is loosely adherent to the septum mally, and has an upward, thinner extension to the lateral crest of the
between the sternal and clavicular parts of pectoralis major. Inferolat intertubercular sulcus (groove) contiguous with the fascia over the an
erally, between pectoralis major and latissimus dorsi, the fascia thickens terior border of deltoid. It is attached to the supracondylar ridge of the


to form the floor of the axilla as the axillary fascia. At the caudal edge lateral epicondyle of the humerus, and is perforated at the level of the
of pectoralis major, a deep lamina of fascia ascends to envelop the junction of the upper threefifths and lower twofifths of the humerus
caudal border of pectoralis minor; it becomes the clavipectoral fascia at by the radial nerve and the radial collateral branch of the profunda
the upper edge of pectoralis minor. The hollow of the armpit is pro brachii artery passing into the anterior compartment from behind. It
duced mainly by the action of this fascia in tethering the axillary skin provides extension for the zone of attachment of lateral head of triceps
to the floor of the axilla; it is sometimes referred to as the suspensory posteriorly, and of brachialis, brachioradialis and extensor carpi radialis
ligament of the axilla. The axillary fascia is pierced by the tail of the longus anteriorly. The medial intermuscular septum extends from the
breast (see Fig. 53.22). The pectoral fascia envelops the lateral margin medial lip of the intertubercular sulcus, where it is contiguous with the
of latissimus dorsi, and the deep and superficial layers then ensheathe fascia of teres major, then blends with the aponeurosis of attachment
that muscle and are attached behind to the spines of the thoracic and of coracobrachialis to the medial aspect of the humerus, and passes as
lumbar vertebrae, blending with the thoracolumbar fascia medially and a thick septum along the medial aspect of the humerus to the medial
caudally. supracondylar ridge of the medial epicondyle. It gives attachment to the
medial head of triceps posteriorly, and brachialis anteriorly. It is perfor
Clavipectoral fascia
ated by the ulnar nerve at about the same level as the radial nerve lat
The clavipectoral fascia is the cranial continuation of the deep lamina erally, together with the superior ulnar collateral artery and the posterior


of the pectoral fascia and the medial continuation of the parietal layer branch of the inferior ulnar collateral artery. At the elbow, the brachial
of the subscapular bursal fascia. Laterally, it is continuous with the fascia is attached to the epicondyles of the humerus, so completing the
coracoacromial ligament above and lateral to the coracoid. It envelops muscular compartments, and the olecranon of the ulna, and is continu
the coracoid, short head of biceps brachii and coracobrachialis. It covers ous with the antebrachial fascia.
the interval between those two muscles and pectoralis minor, which it
envelops, and then traverses the interval between pectoralis minor and Axillary neurovascular sheath
subclavius. It splits around subclavius and is attached to the clavicle The axillary neurovascular sheath is closely contiguous with the pos
anterior and posterior to the groove for subclavius. The posterior layer terior aspect of the clavipectoral fascia. The second part of the axillary
is contiguous with the deep cervical fascia, a condensation of which artery lies behind pectoralis minor; most intimal ruptures of the vessel
forms a tether around the central tendinous part of omohyoid, so indi caused by distraction trauma occur in this part of the vessel.
rectly connecting it to the clavicle. The deep aspect of the posterior
lamina of the clavipectoral fascia blends with the sheath of the axillary Spread of infection
vessels. Medially, it blends with the fascia over the first two intercostal
spaces and is attached to the first rib, medial to subclavius. Occasionally, Available with the Gray’s Anatomy e-book
the fascia thickens to form a band between the first rib and coracoid
process, the costocoracoid ligament, under which the lateral cord of the
brachial plexus is closely applied (Atasoy 2004). The cephalic vein,
BONES
thoracoacromial artery and associated veins and lymphatic vessels, and
the lateral pectoral nerve all pass through the fascia, immediately
cranial to the upper border of pectoralis minor. CLAVICLE
Subscapular fascia


The clavicle lies almost horizontally at the root of the neck (see Figs
The subscapular fascia is thin and attached to the entire circumference 46.7, 29.13). It is a crankshaped cantilever that carries the scapula, so
of the subscapular fossa. Subscapularis is partly attached to its deep enabling the limb to swing clear of the trunk. It transmits part of the
surface medially, an example of the extension of the attachment zone weight of the limb to the axial skeleton. The lateral or acromial end of
of a muscle for more effective action. The fascia extends laterally and the bone is flattened and articulates with the medial side of the
blends with the deep layer of the subscapular bursa in front of the acromion, whereas the medial or sternal end is enlarged and articulates
tendon of subscapularis and with the external layer of the capsule of with the clavicular notch of the manubrium sterni and first costal car
the rotator interval of the glenohumeral joint. Inferiorly, it continues tilage. The shaft is gently curved and resembles the italic letter f in shape,
as the fascia enveloping teres major. being convex forwards (the antecurve) in its medial twothirds and


Shoulder girdle and arm
799.e1
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During forceful flexion/adduction/protraction of the upper limb
across the trunk (e.g. when the scapula is wrenched from the lateral end
of the clavicle in thoracoscapular dissociation), the axillary sheath con
taining the axial vessels and cords of the brachial plexus is forced into
pectoralis minor, which acts as a fulcrum or guillotine, around which
the vessels angle sharply, so rupturing the arteria intima. Acute neural
injuries occur as a result of direct injury (traction, compression, or
both) to the nerve trunks, causing acute sensorimotor deficits, arterial
adventitial haematoma or acute aneurysm expanding within the axillary
sheath to cause the syndrome of causalgia (rapidly progressive, severe
pain in the distribution of the affected nerve trunks with neural defi
cits). Arterial thrombosis following intimal rupture is associated with
late nerve deficits as a result of inadequate neural perfusion, local scar
ring with distortion of the axillary sheath and its contents, and poor
posture of the affected limb.
The neurovascular bundle, enclosed within the sheath, is separated
from the subscapular fascia by a virtual space traversed by the subscapu
lar nerves; this permits full excursion of subscapularis without distor
tion of the neurovascular bundle during normal arm movements. The
tip of the coracoid can be likened to the tip of the shaft of a steering
oar attached to a vessel (the scapula) tethered within the thick clavipec
toral fascia: the effect of pectoralis minor as an antagonist of trapezius
in scapular position and motion control (see below) is optimized by
the wide attachment of the clavipectoral fascia and coracoacromial
ligament to the clavicle and scapula (see Fig. 48.18).
When axillary suppuration occurs, the local fascial arrangement affects
the spread of pus. Suppuration may be superficial or deep to the clavi
pectoral fascia. In the former, an abscess would appear at the edge of
the anterior axillary fold or in the groove between deltoid and pectoralis
major; in the latter, pus would tend to track upwards in the axillary


neurovascular sheath and appear at the root of the neck, taking the
direction of least resistance. Lymphangitis in the medial aspect of the
arm suggests infection deep to the clavipectoral fascia with lymphatic
obstruction. When an axillary abscess is incised, the knife should
enter the axillary ‘base’, midway between the anterior and posterior
margins and near the thoracic side, to avoid the lateral thoracic, sub
scapular and axillary vessels on the anterior, posterior and lateral walls,
respectively.


Shoulder girdle and arm
800
6
noiTCeS
Fig. 48.6 The left clavicle, showing sites of
muscular and ligamentous attachment and
1 articular surfaces. A, Superior view. Key: 1,
sternocleidomastoid (clavicular head); 2, sternal
4 end; 3, pectoralis major; 4, trapezius; 5, acromial
end; 6, deltoid. B, Inferior view. Key: 1, pectoralis
2 major; 2, for costoclavicular ligament; 3, for first
costal cartilage; 4, for sternum; 5, sternohyoid; 6,
5 subclavius; 7, deltoid; 8, for acromion; 9, trapezoid
line; 10, trapezius; 11, conoid tubercle.
3 6
A
7
1
2 8
3 9
4
10
11
5
6
B
concave forwards (the retrocurve) in its lateral third (Fig. 48.6). The the conoid tubercle and trapezoid line (see Fig. 48.6B), transmit the
inferior aspect of the intermediate twofifths is grooved in its long axis weight of the upper limb to the clavicle, and are counteracted by the
for the attachment of subclavius. Laterally, the internal architecture of cervical part of trapezius, which supports its lateral part (see Fig. 48.18).
the clavicle is trabecular; there is a medullary cavity in its medial two
Medial three-fifths
thirds. The cortical bone is thickest at the transition zone between the
antecurve and retrocurve. The female clavicle is typically shorter, thinner, The medial threefifths of the shaft of the clavicle are cylindrical or
less curved and smoother. Midshaft circumference is the most reliable prismoid in form and have four surfaces, although the inferior surface
single indicator of sex; a combination of this measurement with weight is often reduced to a mere ridge. The anterior surface is roughened over


and length yields more reliable and consistent results. The clavicle is most of its extent but is smooth and rounded laterally, where it forms
subcutaneous throughout its whole length and accordingly can be pal the upper boundary of the infraclavicular fossa. The upper surface is
pated for its entire length; the medial (sternal) end forms an expanded, roughened medially and smooth laterally. The posterior surface is
bluntfaced margin of the jugular notch. The anterior border of the smooth and featureless medially; its lateral half bears a groove in the
lateral (acromial) end is not readily distinguished from the acromion; long axis of the bone. The inferior surface is marked near its sternal end
the attachment of deltoid obscures the anterior aspect of the acromio by a roughened oval impression, which is often depressed below the
clavicular joint. By contrast, the posterior border of the lateral end surface. Its margins give attachment to the costoclavicular ligament,
forms the anterior margin of a roughly parabolic hollow under the which connects the clavicle to the upper surface of the first rib and its
lateral fibres of trapezius, the posterior border being formed by the cartilage. Rarely, this area is smooth or raised to constitute an eminence
anterior border of the spine of the scapula. The hollow will admit at that may form a synovial pseudarthrosis with the upper surface of the
least one palpating finger. If the pulp of the finger is placed on the spine first rib; in older subjects, an extraarticular synostosis may form.
of the scapula as far laterally as the hollow will permit, the nail will The medial threefifths provide attachment, anteriorly, for the cla
inevitably point to the posterior capsule of the acromioclavicular joint; vicular head of pectoralis major. The clavicular head of sternocleido
this landmark is always palpable, even in wellmuscled individuals, mastoid is attached to the medial half of the superior surface, but the
when other shoulder landmarks can be obscured. marking on the bone is not conspicuous. The smooth, posterior surface
is devoid of muscular attachments, except at its lower part immediately
Lateral two-fifths
adjoining the sternal end, where the lateral fibres of sternohyoid are