opponens

noun
op·​po·​nens | \ ə-ˈpō-ˌnenz How to pronounce opponens (audio) \
plural opponentes\ ˌäp-​ə-​ˈnen-​(ˌ)tēz How to pronounce opponentes (audio) \ or opponens

Medical Definition of opponens

: any of several muscles of the hand or foot that tend to draw one of the lateral digits across the palm or sole toward the others