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Radial Nerve AnatomyEpisode 1

Radial Nerve

• Originates as the terminal branch of the posterior cord of the brachial plexus:– roots from C5, 6, 7, 8, & T1.– Largest branch of brachial plexus

Cutaneous Innervation

• Posterior cutaneous nerve of arm• Inferior lateral cutaneous nerve of arm • Posterior cutaneous nerve of forearm• Superficial branch of radial nerve

Motor Innervation

• Muscular branches of radial nerve above elbow:– Triceps– Anconeus– Brachoradialis – ECRL

Motor Innervation

• Muscular Branches below elbow:– ECRB (varied innervation: superficial or PIN)– Supinator

• PIN:– Superficial• EDC, ECU,, EDM

– Deep• APL, EPL, EPB, EI

Course of Radial Nerve


• Largest terminal branch of posterior cord• Enters posterior aspect of humerus through lower

triangular interval– Teres major (superior)– Long head triceps (medial)– Humerus (lateral)

• Gives posterior cutaneous nerve of arm in axilla


• Comes to lie in distal part of spiral groove with profundi brachii artery– Beneath lateral head of triceps and proximal to origin of

medial head

• Gives branches to triceps, anconeus and inferior lateral cutaneous nerve of arm

• Through lateral intermuscular septum 10-12cm above lateral epicondyle


• In anterior compartment of arm lies between brachialis and brachioradialis– 1-3 accessory branches to brachialis– Large branch to BR (sometimes this branch given

by superficial radial below elbow)

• ECRL generally innervated proximal to elbow joint


• Enters the forearm anterior to lateral epicondyle– More specifically over articulation between capitulum and

radial head• ECRB innervated distal to elbow joint either PIN or

superficial branch

• At some point 3cm above or below divides into:– Superficial radial– PIN

Course of Superficial Radial Nerve

• Runs over supinator,PT and FDS• Lies under BR with radial artery on its ulnar side from

1/3 of the way down forearm• Passes posteriorly through tendon of BR proximal to

radial styloid• Passes over tendons of snuffbox• Terminates as cutaneous branches to dorsum of

hand and lateral 3.5 digits short of nailbeds

Posterior Interosseous Nerve

• Gains access to posterior forearm by diving posterior and laterally through ligament of Frohse and the interval between the two heads of supinator

• Arcade of Frohse is a fibrous arch originating lateral epicondyle superior part of superficial layer of supinator– German Anatomist, Fritz Frohse (1871-1916)

Posterior Interosseous Nerve

• After exiting the supinator divides into deep and superficial muscular branches– Superficial• EDC, ECU, EDM

– Deep• APL, EPL, EPB, EI

Radial Nerve Compression Sites

• PIN– As it traverses the radial tunnel it encounters 4

sites of compression– “Radial tunnel syndrome”• entrapment neuropathy

Radial Tunnel Syndrome

1. Fibrous bands• Tight fibrous bands anterior to radial head at entrance of

tunnel

2. Arcade of Frohse• Most common

3. Leash of Henry• Radial recurrent vx that fan out over radial nn

4. Medial border of ECRB

Cheiralgia paresthetica

• Described by Robert Wartenberg 1932• Superficial radial nerve neuritis– Wartenberg Syndrome

• Causes:– Trauma, iatrogenic, compression (muscle anomalies,

fascial bands, thrombosis radial recurrent artery, tumour, haemorrhage)

• Symptoms:– Dysaesthesia over distribution

Radial Nerve Palsy

• Causes:– Fractures esp humerus, Monteggia– Penetrating injury/trauma– “Saturday Night Palsy” “Crutches”– Iatrogenic– tumour

Episode IIRadial Nerve Tendon Transfers