The anterior interosseous nerve is a branch of the median nerve in the forearm.

It is purely motor and supplies:

• flexor digitorum profundus - flexes distal phalanges of index and middle fingers
• flexor pollicus longus - flexes thumb
• pronator quadratus muscle - pronates hand

Damage may occur without any obvious cause or may develop as a result of external pressure on the forearm or from gripping tightly in association with pronation.

Recovery usually occurs spontaneously over 2 - 3 months. Exploration is indicated if the injury persists.