Anterior interosseous nerve of forearm

The anterior interosseous nerve of forearm is a key motor branch of the median nerve, which innervates muscles in the deep compartment of the anterior forearm. It derives its motor fibers from the C7 and C8 spinal segments.

Course

The anterior interosseous nerve branches off the median nerve as it passes through the cubital fossa (in front of the elbow), between the humeral and ulnar heads of the pronator teres muscle. After branching, the anterior interosseus nerve descends along the anterior surface of the interosseous membrane, travelling deep within the forearm and accompanied by the anterior interosseus artery and vein.

Innervation

The anterior interosseus nerve of forearm provides motor innervation to the following deep muscles of the anterior forearm:

• Flexor pollicis longus

• Lateral half of the flexor digitorum profundus, which forms the tendons for the index and middle fingers

• Pronator quadratus

In addition to its muscular branches, the anterior interosseous nerve also gives articular branches that supply the distal radioulnar and wrist joints.