Abductor Pollicis Brevis

The Abductor Pollicis Brevis arises from the flexor retinaculum and the tubercle of the scaphoid. It inserts into the proximal phalanx and acts as a true abductor of the thumb. The motor recurrent branch of the median nerve passes over the flexor pollicis brevis muscle and passes deep to the abductor pollicis brevis.