Abductor pollicis longus

The abductor pollicis longus (Latin: musculus abductor pollicis longus) is a flat muscle of the forearm that stretches between the ulna, radius and first metacarpal bone. It belongs to the posterior compartment of the forearm muscles, and it lies in the second (deep) layer. Besides abduction of the thumb, the abductor pollicis longus also provides thumb extension.

Origin

The abductor pollicis longus originates from the posterior surfaces of the ulna and radius and interosseous membrane of the forearm.

Insertion

From the origin site, the abductor pollicis longus descends and forms a tendon that continues to go downward to reach the dorsal surface of the hand. The tendon of the abductor pollicis longus inserts on the base of the first metacarpal bone.

Action

The abductor pollicis longus muscle provides the abduction and extension of the thumb at the first carpometacarpal joint.

Innervation

The abductor pollicis longus is innervated by the posterior interosseous nerve - a branch of the radial nerve (C7, C8).

Blood supply

The abductor pollicis longus muscle receives arterial blood supply from the anterior and posterior interosseous arteries. Both are branches of the common interosseous artery.