The Radial nerve is a continuation of the posterior cord of the brachial plexus. Its roots emerge at C6, C7, C8 en Th1 levels.
First it runs in the axilla and winds around the posterior aspect of the humerus, which it crosses from medial to lateral.
It continues in the lateral bicipital groove, lateral to the biceps (in the lateral intermuscular septum), and down to the cubital fossa.
At the level of the humeroradial joint line it divides into two terminal branches.
- an anterior sensory branch ( radialis superficialis) which provides sensory innervation for the dorsal aspect of the thumb, index- and middle finger.
- a posterior motor branch, the n. radialis profundus (or posterior interosseus).
Compression Localisations
- Level with the posterior and lateral side of the humerus , at the intersection between upper and middle third at the septum intermusculare laterale
- Most often the radial nerve is compressed at the level of the supinator muscle where the n. posterior interosseus passes under ‘ the arcade of Frohse’. This neurocompression is called the "Radial Tunnel Syndrome"