Adductor pollicis muscle
[1] The oblique head (Latin: adductor obliquus pollicis) arises by several slips from the capitate bone, the bases of the second and third metacarpals, the intercarpal ligaments, and the sheath of the tendon of the flexor carpi radialis.[2] It is triangular, arising by a broad base from the lower two-thirds of the palmar surface of the third metacarpal bone; the fibers converge, to be inserted with the medial part of the flexor pollicis brevis and the oblique head into the ulnar side of the base of the proximal phalanx of the thumb.[2] The radial artery passes between the two heads, travelling from the back of the hand into the palm, where it forms the deep palmar arch.[3] Between the oblique and transverse heads is a thin fibrous arcade which the nerve passes as it traverses the palm laterally.The adductor pollicis evolved from the contrahens I muscle as man's ancestors' thumbs and big toes became opposable.