Abductor digiti minimi muscle of hand
Abductor digiti minimi is a short intrinsic muscle of the hand. It belongs to the group of muscles collectively called hypothenar muscles due to their acting on the 5th finger. Besides abductor digiti minimi, other hypothenar muscles include flexor digiti minimi brevis and opponens digiti minimi.
The main function of abductor digiti minimi involves abduction of the 5th finger, as well as flexion of its proximal phalanx. Along with other hypothenar muscles, this muscle forms the hypothenar eminence on the medial side of the palm.
This article will teach you all you need to know about the anatomy of abductor digiti minimi muscle, including its origin, insertion, neurovascular supply and function.
|Origin||Pisiform bone (Pisohamate ligament, Tendon of flexor carpi ulnaris)|
|Insertion||Ulnar side of base of proximal phalanx of digit 5, Extensor expansion of digit 5|
|Action||Metacarpophalangeal joint 5: Finger abduction and flexion;
Interphalangeal joints: Finger extension
|Innervation||Deep branch of ulnar nerve (C8, T1)|
|Blood supply||Palmar branch of ulnar artery, palmar digital artery, superficial palmar arch|
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.
Together, these three muscles form the hypothenar eminence.
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.
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).
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.
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