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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.
Abductor pollicis longus | |
Origin | Posterior surfaces of radius and ulna, interosseous membrane of forearm |
Insertion | Base of 1st metacarpal bone |
Action | Thumb abduction and extension |
Innervation | Posterior interosseous nerve of radial nerve (C7, C8) |
Blood supply | Anterior and posterior interosseous arteries |
![Forearm muscles (colored), Upper extremity, Muscles, Human arm, Anteromedial view, Dorsolateral view](https://anatomy.net/uploads/88b91b2e-37af-4ec6-94a9-3ddc7724e28c.jpg?width=1200)
Origin
The abductor pollicis longus originates from the posterior surfaces of the ulna and radius and interosseous membrane of the forearm.
![Abductor pollicis longus, Origin of abductor pollicis longus, Insertion of abductor pollicis longus, Forearm muscles, Muscles of forearm, Posterior compartment muscles, Posterior compartment of forearm muscles, Human muscles, Human hand](https://anatomy.net/uploads/08ef68be-36d2-4141-903c-5c724755597c.jpg?width=1200)
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.
![Abductor pollicis longus, Insertion of abductor pollicis longus, Forearm muscles, Muscles of forearm, Posterior compartment muscles, Posterior compartment of forearm muscles, Human muscles, Human hand](https://anatomy.net/uploads/fd0c165e-d2aa-4c85-b5cf-974bc4f2f139.jpg?width=1200)
Action
The abductor pollicis longus muscle provides the abduction and extension of the thumb at the first carpometacarpal joint.
![Abductor pollicis longus, Extensor pollicis brevis, Action of abductor pollicis longus, Function of abductor pollicis longus, Action of extensor pollicis brevis, Function of extensor pollicis brevis, Forearm muscles, Muscles of forearm, Posterior compartment muscles, Posterior compartment of forearm muscles, Human muscles, Human hand](https://anatomy.net/uploads/188a5255-c657-4712-8f9b-2b3cfdd0a51f.jpg?width=1200)
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.