opponens digiti minimi

noun

opponens dig·​i·​ti min·​i·​mi -ˈdij-ə-ˌtī-ˈmin-ə-ˌmī 

: a triangular muscle of the hand that arises from the hamate and adjacent flexor retinaculum, is inserted along the ulnar side of the metacarpal of the little finger, and functions to abduct, flex, and rotate the fifth metacarpal in opposing the little finger and thumb