The opponens digiti minimi (opponens digiti quinti in older texts) is a muscle in the hand. It is of a triangular form, and placed immediately beneath the palmaris brevis, abductor minimi digiti, and flexor brevis minimi digiti. It is one of the three hypothenar muscles that controls the little finger.
It arises from the convexity of the hamulus of the hamate bone, and contiguous portion of the transverse carpal ligament; it is inserted into the whole length of the metacarpal bone of the little finger, along its ulnar margin.
Opponens minimi digiti serves to flex and laterally rotate the 5th metacarpal about the 5th carpometacarpal joint, as when bringing little finger and thumb into opposition. It is innervated by the deep branch of the ulnar nerve.