Summary Opponens Pollicis Origin Flexor retinaculum and tubercles of scaphoid and trapezium Insertion Lateral side of 1st metacarpal Action Draws 1st metacarpal into adduction to oppose thumb toward center of palm and rotates it medially Innervation Recurrent branch of median nerve (C8, T1) Arterial supply Superficial palmar branch of the radial artery