Abductor digiti minimi muscle of hand

Origin and insertion

Abductor digiti minimi mainly arises from the pisiform bone. Other sites of origin include pisohamate and pisometacarpal ligaments; these connect the pisiform bone to the hamate and metacarpal bones, respectively.

Some fibers also arise from the tendon of flexor carpi ulnaris that is also attached to the pisiform bone. 

The muscle fibers converge into a tendon and insert into the ulnar side of the proximal phalanx of the little finger and its extensor expansion.

The following quiz helps you improve your knowledge about the anatomy of the hand muscles.

Relations

Abductor digiti minimi is the most medial of the hypothenar muscles, situated along the ulnar border of the flexor digiti minimi brevis and superficial to opponens digiti minimi muscle.

Together, these three muscles form the hypothenar eminence.

Innervation

Like other hypothenar muscles, abductor digiti minimi receives nervous supply from the deep branch of the ulnar nerve, derived from root values C8 and T1.

Blood supply

Abductor digiti minimi receives arterial blood supply from the palmar branch of ulnar artery, palmar digital artery, as well as branches of the ulnar side of the superficial palmar arch. The venous blood from the muscle is drained via the venous networks of the palm into the deep veins of the arm (vv. ulnares).

Function

Main function of the abductor digiti minimi is abduction and flexion of the 5th finger at the metacarpophalangeal joint, and thereby moving it away from the 4th finger. At the interphalangeal joint, this muscle also aids the flexion of the 5th finger due to its attachment to its extensor expansion. The importance of abductor digiti minimi lies in the fact that it is crucial for grasping large objects with outspread fingers, such as a basketball.