opponens pollicis (muscle)

op·po·nens pol·li·cis (mus·cle)

thenar muscle of palm; origin, ridge of trapezium and transverse carpal ligament (flexor retinaculum); insertion, anterior surface of the full length of the shaft of the first metacarpal bone; action, acts at carpometacarpal joint to "cup" palm, enabling one to oppose thumb to other fingers; nerve supply, median.
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