Long abductor muscle of first digit [Abductor pollicis longus muscle, Oblique extensor muscle of carpus]

Origin: Lateral surface of the ulna and radius, and the interosseous membrane.

Insertion: Medial on the proximal end of metacarpal 1 where there is a sesamoid bone embedded in it.

Action: Abduction and flexion of the first digit and medial deviation of the forepaw.

Nerve: Radialis.