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Extensor pollicis brevis
The extensor pollicis brevis (Latin: musculus extensor pollicis brevis) is a flat, thin and relatively short muscle of the forearm that extends between the radius and the proximal phalanx of the thumb. It belongs to the posterior compartment of the forearm muscles, and it lies in the second layer.
Extensor pollicis brevis | |
Origin | Posterior surface of distal radius, interosseous membrane of forearm |
Insertion | Base of proximal phalanx of 1st finger |
Action | Thumb 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/1ebec1a9-8570-40d1-8fa1-4e978c4c8a21.jpg?width=1200)
Origin
The extensor pollicis brevis muscle originates from the posterior surface of the distal radius and interosseous membrane of the forearm.
![Extensor pollicis brevis, Origin of extensor pollicis brevis, Insertion of extensor pollicis brevis, Forearm muscles, Muscles of forearm, Forearm extensors, Posterior compartment muscles, Posterior compartment of forearm muscles, Human muscles, Human arm](https://anatomy.net/uploads/f45ef8c0-e57f-482f-add3-8c83e2bdc3ca.jpg?width=1200)
Insertion
The extensor pollicis brevis inserts on the base of the proximal phalanx of the first finger.
![Extensor pollicis brevis, Forearm muscles, Muscles of forearm, Posterior compartment muscles, Posterior compartment of forearm muscles, Human hand, Forearm extensors](https://anatomy.net/uploads/c222d268-3d6b-45a4-8273-e8abbbbc9d58.jpg?width=1200)
Action
The extensor pollicis brevis muscle extends the thumb at the first carpometacarpal and metacarpophalangeal joints.
![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/aacbbf7c-5963-4bb8-9eb8-674d4a029649.jpg?width=1200)
Innervation
The extensor pollicis brevis is innervated by the posterior interosseous branch of the radial nerve (C7, C8). The radial nerve arises from the brachial plexus.
Blood supply
The extensor pollicis brevis muscle receives arterial blood supply from the posterior and anterior interosseous arteries. Both are branches of the common interosseous artery.