Investigation of two possible compression sites of the deep branch of the radial nerve and nerve supply of the extensor carpi radialis brevis muscle.

The posterior interosseous nerve arises from the deep branch of the radial nerve, and compression by adjacent structures results in posterior interosseous nerve syndrome. Sixty upper limbs from 30 Turkish subjects (18 males and 12 females) were dissected to reveal the course of the posterior interosseous nerve and to examine possible compression sites at the proximal and distal edges of the supinator muscle, and the exit of the nerve from the extensor carpi radialis brevis muscle. Posterior interosseous nerve syndrome is most probably caused by the tendinous part of the supinator muscle at the proximal edge.