The extensor pollicis longus is a muscle located in the deep compartment of the posterior forearm. Specifically, its tendon passes through the third extensor compartment at the wrist, where it serves as the ulnar border of the anatomical snuffbox.
The extensor pollicis longus originates from the posterior surface of the ulna and interosseous membrane. It subsequently attaches to the base of the distal phalanx of the thumb.
The extensor pollicis longus is responsible for the extension of the interphalangeal, metacarpophalangeal, and carpometacarpal joints of the thumb.
The extensor pollicis longus is innervated by the radial nerve's posterior interosseous branch.
The extensor pollicis longus is primarily supplied by the ulnar artery.
