Abductor pollicis brevis muscle

Abductor pollicis brevis muscle
origin
Flexor retinaculum , scaphoid and trapezium
approach
Outside of the basic phalanx of the thumb
function
Spreading the thumb
Innervation
Median nerve of the brachial plexus
Spinal segments
C7-Th1

The abductor pollicis brevis muscle ( Latin for "short thumb spreader") is one of the muscles of the ball of the thumb . It spreads the thumb together with the abductor pollicis longus muscle ( abduction ). While the abductor pollicis longus muscle spreads the thumb to the side, the abductor pollicis brevis muscle spreads the thumb in the direction of the palm (palmar abduction). Further functions are to support the flexion of the thumb joint and the extension of the thumb joint.