The adductor pollicis muscle is the deepest of the thenar group. It arises by two heads, whose fibers are directed towards one another, at an angle. The oblique head originates from the radiate carpal ligament (at the capitate bone) and the palmar surface of the second and third metacarpal bone. The transverse head arises from the palmar surface of the second and third metacarpal bone. Then these two muscle bundles converge together at an angle to be inserted into the base of the proximal phalanx of thumb, the ulnar sesamoid bone, and the capsule of the metacarpophalangeal joint. Name in Latin: musculus adductor pollicis. "Thenar" is the fleshy portion at the base of thumb.
Action
Upon contraction, it adducts the thumb (it pulls it medially towards the radial border of palm of hand). It also assists in flexing the thumb proximal phalanx.
Innervation
The adductor pollicis muscle is innervated by branches of the ulnar nerve (C8). Let us remember that the ulnar nerve springs from the brachial plexus.
Blood Supply
It receives oxygenated blood from secondary branches of the superficial and deep palmar arches, which are the arterial anastomoses of the radial and ulnar artery.
Below, a picture of muscles of right hand, exposing the adductor pollicis, with its two heads
