Extensor pollicis brevis

The  extensor pollicis brevis (or extensor pollicis brevis muscle, latin: musculus extensor pollicis brevis) is flat, thin muscle of the forearm that belongs to the posterior muscle group, lying in the second or deep layer.


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


The extensor pollicis brevis descends obliquely and inserts at the base of the proximal phalanx of the first finger of the hand, known as the thumb.


The main function of the extensor pollicis brevis is to extend the proximal phalanx of the thumb.


The extensor pollicis brevis is innervated by the radial nerve.