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Extensor pollicis longus

The extensor pollicis longus (Latin: musculus extensor pollicis longus) is a slim muscle of the forearm that extends between the ulna and the first metacarpal bone. It belongs to the posterior compartment of the forearm muscles, lying in the second (deep) layer. As the name suggests, the extensor pollicis longus provides thumb extension.

Extensor pollicis longus
Origin Posterior surface of ulna, interosseous membrane of forearm
Insertion Base of distal phalanx of thumb
Action Extension of thumb
InnervationPosterior interosseous nerve of radial nerve (C7, C8)
Blood supply Anterior and posterior interosseous arteries



The extensor pollicis longus muscle originates from the posterior surface of the ulna and interosseous membrane of the forearm.



The extensor pollicis longus inserts on the base of the distal phalanx of the thumb.



The extensor pollicis longus muscle extends the thumb at the metacarpophalangeal and interphalangeal joints of the thumb.



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


Blood supply

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