Corpus: Abductor pollicis longus muscle

The abductor pollicis longus muscle originates from the posterior facies of the ulna and radius, as well as the antebrachial interosseous membrane. Alongside the extensor pollicis brevis muscle, its tendon traverses the initial tendon compartment of the extensor retinaculum, ultimately attaching to the base of the first metacarpal bone and the trapezium bone.

The muscle is innervated by the ramus profundus of the radial nerve with fibers from segments C7 and C8.

The abductor pollicis longus muscle is responsible for abduction of the thumb and radial abduction of the hand. Additionally, it is involved in supination of the hand.