Opponens pollicis

The opponens pollicis is one of the four muscles of the thumb located on the radial side of the palm. It lies deep to the abductor pollicis brevis, superficial to the first metacarpal bone, and lateral to the flexor pollicis brevis. The superficial head of the flexor pollicis brevis is often blended with the opponens pollicis. This muscle also contributes to the formation of the thenar eminence and is therefore classified as a thenar muscle.