Origin: Trapezium and transverse carpal ligament
Insertion: Metacarpal bone of the thumb on its radial side
Nerve: Median nerve
Action: Opposition of the thumb
The Opponens pollicis is a small, triangular muscle, lying deep to the abductor pollicis brevis and lateral to the flexor pollicis brevis.
It arises from the ridge on the greater multangular and from the transverse carpal ligament, passes downward and lateralward, and is inserted into the whole length of the metacarpal bone of the thumb on its radial side.