Posterior interosseous nerve

The posterior interosseous nerve (or dorsal interosseous nerve) is a nerve in the forearm. It is the continuation of the deep branch of the radial nerve, after this has crossed the supinator muscle. It is considerably diminished in size compared to the deep branch of the radial nerve. The nerve fibers originate from cervical segments C7 and C8.

Course

It descends on the interosseous membrane, in front of the Extensor pollicis longus, to the back of the carpus, where it presents a gangliform enlargement from which filaments are distributed to the ligaments and articulations of the carpus.

Supply

It supplies all the muscles on the radial side and dorsal surface of the forearm, except the Anconæus, Brachioradialis, Extensor carpi radialis longus. In other words, it supplies the following muscles:

• Extensor carpi radialis brevis - deep branch of radial nerve
• Extensor digitorum
• Extensor digiti minimi
• Extensor carpi ulnaris
• Supinator muscle - deep branch of radial nerve
• Abductor pollicis longus
• Extensor pollicis brevis
• Extensor pollicis longus
• Extensor indicis

Entrapment

The posterior interosseous nerve may be entrapped at the Arcade of Frohse, which is part of the Supinator muscle. Posterior interosseous neuropathy is purely a motor syndrome resulting in finger drop, and radial wrist deviation on extension.

See also

• Anterior interosseous nerve

External links

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