Brachial plexus

Nerve supply of upper limb

Common clinical syndromes and presentation

Dr. Patrick ReynoldsF2 Trauma & Orthopaedics

•Supplied by C5, C6 and C7

•Formed by a branch of the lateral cord (superior and medial trunks)

•Supplies “BBC” muscles - Biceps Brachii, Brachialis and Coracobrachialis

•Gives off lateral cutaneous nerve of the forearm – important structure to identify in surgery around the ACF

Musculocutaneous nerve

•Supplied by C5-8, T1 (inconsistent)

•Formed by a continuation of the posterior cord)

•Supplies Extensor muscles and brachioradialis(extensor paradox) and abductor pollicis longus

•Proximally runs around the spiral groove, dives deep through lateral intermuscular septum, runs anterolaterally around the radial head and reappears through the extensor compartment in the forearm

Radial nerve

•Supplied by C5-8, T1 (inconsistent)

•Formed by a confluence of the medial and lateral cords

•Supplies flexor compartment of forearm, three thenar muscles and two lumbricals of hand

•Supplies deep compartment as the anterior interosseuous nerve

•Anterior interosseous nerve supplies radial half of FDP, FPL and pronator quadratus, sensory to wrist and carpal tunnel

Median nerve

•Supplied by C7, C8 T1

•Direct continuation of medial cord (C8, T1) with contribution of (C7) fibres from axilla

•Supplies some flexors on ulnar side, ulnar side of FDP, all intrinsic muscles, lumbricals & interosseiof hand excluding LOAF

•Runs posteriorly on humerus, pass through cubital tunnel

Ulnar nerve

Ulnar nerve lesion at wrist or just below elbow gives previous “claw” appearance

Position caused by loss of lumbrical function (flex MCPJ, extend PIPJ) with unopposed effect of finger extensors

Paradoxically a higher lesion of the ulnar nerves leads to less severe “clawing”, why?

FDP on ulnar side receives ulnar nerve supply. Paralysis of ulnar FDP occurs in high lesions giving fingers a less flexed appearance

Injury is more severe but appearance is better, hence “Paradox”

Ulnar claw hand

Radial wrist drop

Erb’s Palsy

Traction injury to C5, C6 often birth injury during difficult delivery

Abductors and lateral rotators of shoulder and the supinators are paralysed

Arm hangs by side, medially rotated, pronatedwith loss of sensation on the lateral side of arm and forearm

Erb’s Palsy

Damage to the lowest roots (C8, T1)

Can also be a birth injury during breech delivery where arms remain above head

Small muscles of hand are most affected. Often get clawing

Ulnar sensory loss

Appearance as per claw hand

Klumpke’s paralysis

LOAF – Intrinsic muscles supplied by median nerve

lateral two lumbricals, opponens pollicis, abductor pollicisbrevis, flexor pollicis brevis

A OF A OF A –

Thenar (lateral to medial-palmar surface):

Abductor pollicis brevis Opponens pollicis Flexor pollicisbrevis Adductor pollicis

Hypothenar (lateral to medial-palmar surface):

Opponens digiti minimi Flexor digiti minimi Abductor digiti minimi

Useful mnemonics for hands