Abductor pollicis brevis muscle

The abductor pollicis brevis muscle is a muscle in the hand that abducts the thumb (pulls it away from the index finger).

Origin
The abductor pollicis brevis muscle originates from the wrist, at the tubercle of the scaphoid bone and the flexor retinaculum.

Insertion
The abductor pollicis brevis muscle inserts on the thumb, at the radial sesamoid of the proximal phalanx of the thumb and the tendon of the extensor pollicis longus muscle.

Action
The abductor pollicis brevis muscle abducts the thumb at the metacarpophalangeal and carpometacarpal joints.

Innervation
The abductor pollicis brevis muscle is innervated by the recurrent branch of the median nerve (C8, T1). In some individuals, it is innervated by the ulnar nerve.