Opponens digiti minimi is one of the hypothenar muscles. It lies deep to the flexor and abductor muscles.
It originates from the hook of the hamate bone of the wrist and the flexor retinaculum. It passes in an ulnar and distal direction to insert into the ulnar border of the shaft of the fifth metacarpal bone.
It is innervated by the deep branch of the ulnar nerve (C8,T1).
The action of opponens digiti minimi are to oppose the little finger to thumb by:
- flexion of the fifth metacarpal
- lateral rotation of the carpometacarpal joint of the fifth digit
- lateral rotation of the metacarpophalangeal joint of the fifth digit