The radial nerve constitutes the termination of the posterior cord of the brachial plexus and contains fibres derived from the 5th, 6th, 7th and 8th cervical nerves. It descends from the axilla winding posteriorly around the humerus.
It is both motor and sensory:
- motor - supplies the triceps, anconeus, brachioradialis extensor carpi radialis longus, and through the posterior interosseous branch, extensor carpi radialis brevis, supinator, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris, the extensors of the thumb - extensor pollicis longus and brevis - and extensor indicis.
- sensory - lower half of the radial aspect of the arm, middle of the posterior aspect of the forearm, and the dorsal aspect of the thumb and radial 2" fingers, except nail beds. The distribution to the dorsum of the hand is variable and clinically, sensation should be tested only on the dorsum itself, not extending along the fingers.
Last reviewed 01/2018