The adductor pollicis is a muscle in the hand and acts on the thumb. It originates on the transverse head of the third metacarpal, the oblique head of the base of the second and third metacarpals, and the trapezoid and capitate bones. It inserts on the base of the proximal phalanx and ulnar sesamoid. This muscle acts to adduct and flex the thumb. Trigger points cause pain and aching along the outside of the thumb and hand, spillover pain may reach the thenar eminence.