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.

Origin

The extensor pollicis brevis muscle originates from the posterior surface of the distal radius and interosseous membrane of the forearm.

Insertion

The extensor pollicis brevis inserts on the base of the proximal phalanx of the first finger.

Action

The extensor pollicis brevis muscle extends the thumb at the first carpometacarpal and metacarpophalangeal joints.

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.