Dorsal interosseous nerve

Posterior interosseous nerve
The Supinator. (Deep branch of radial nerve labeled at upper right and lower right. Dorsal interosseous is this nerve after passing the supinator, at lower right.)
Details
From	Deep branch of the radial nerve
Innervates	Extensor carpi radialis brevis Extensor digitorum Extensor digiti minimi Extensor carpi ulnaris Supinator muscle Abductor pollicis longus Extensor pollicis brevis Extensor pollicis longus Extensor indicis
Identifiers
Latin	nervus interosseus antebrachii posterior
TA	A14.2.03.055
FMA	77559
Anatomical terms of neuroanatomy []

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.

It descends along the interosseous membrane, anterior to the extensor pollicis longus muscle, 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.

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:

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.

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)