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AAAC31 21/5/05 10:50 AM Page 73
The ulnar nerve (C8,T1) (Fig. 31.1)
Supraclavicular branches
• Type: mixed sensory and motor.
• Suprascapular nerve (C5,6): passes through the suprascapular
• Origin: from the medial cord of the brachial plexus.
notch to supply supra- and infraspinatus muscles.
• Course and branches: it runs on coracobrachialis to the mid-arm Other branches of the brachial plexus
where it pierces the medial intermuscular septum with the superior • Long thoracic nerve (of Bell) (C5,6,7): supplies serratus anterior.
ulnar collateral artery to enter the posterior compartment. It winds
under the medial epicondyle and passes between the two heads of Infraclavicular branches
flexor carpi ulnaris to enter the forearm and supplies flexor cari ulnaris • Medial and lateral pectoral nerves: supply pectoralis major and
and half of flexor digitorum profundus. In the lower forearm the artery minor.
lies lateral to the ulnar nerve and the tendon of flexor carpi ulnaris. Here • Medial cutaneous nerves of the arm and forearm.
dorsal and palmar cutaneous branches are given off. The ulnar nerve • Thoracodorsal nerve (C6,7,8): supplies latissimus dorsi.
passes superficial to the flexor retinaculum and subsequently divides • Upper and lower subscapular nerves: supply subscapularis and
into terminal branches. These are: teres major.
• The superficial terminal branchaterminates as terminal digital
nerves supplying the skin of the little and medial half of the ring Brachial plexus injuries
fingers. Erb–Duchenne paralysis
• The deep terminal branchasupplies the hypothenar muscles as Excessive downward traction on the upper limb during birth can result
well as two lumbricals, the interossei and adductor pollicis. in injury to the C5 and C6 roots. This results in paralysis of the deltoid,
• Effect of injury (Fig. 31.2): occurs commonly at the elbow (e.g. the short muscles of the shoulder, brachialis and biceps. The combined
fracture of the medial epicondyle) or at the wrist due to a laceration. effect is that the arm hangs down by the side with the forearm pronated
• Motor deficitawith low lesions the hand becomes ‘clawed’. Owing and the palm facing backwards. This has been termed the ‘waiter’s tip’
to the loss of interossei and lumbrical function the metacarpopha- position.
langeal joints of the ring and little fingers hyperextend and their
interphalangeal joints flex. The ‘clawing’ is attributed to the un- Klumpke’s paralysis
opposed action of the extensors and flexor digitorum profundus. Excessive upward traction on the upper limb can result in injury to the
When injury occurs at the elbow or above, the ring and little fingers T1 root. As the latter is the nerve supply to the intrinsic muscles of the
are straighter because the ulnar supply to flexor digitorum profun- hand this injury results in ‘clawing’ (extension of the metacarpopha-
dus is lost. The small muscles of the hand waste with the exception langeal joints and flexion of the interphalangeal joints) due to the
of the thenar and lateral two lumbrical muscles (supplied by the unopposed action of the long flexors and extensors of the fingers. There
median nerve). is often an associated Horner’s syndrome (ptosis, pupillary constric-
• Sensory deficitaoccurs to the palmar and dorsal surfaces of the tion and ipsilateral anhidrosis) as the traction injury often involves the
hand and medial 11/2 digits. The loss is highly variable due to cervical sympathetic chain.
overlap.

Nerves of the upper limb II 73