The flexor digiti minimi brevis is a hypothenar muscle in the hand that flexes the little finger (digit V) at the metacarpophalangeal joint. It lies lateral to the abductor digiti minimi when the hand is in anatomical position.

Structure

The flexor digiti minimi brevis arises from the hamulus of the

hamate bone The hamate bone (from Latin hamatus, "hooked"), or unciform bone (from Latin ''uncus'', "hook"), Latin os hamatum and occasionally abbreviated as just hamatum, is a bone in the human wrist readily distinguishable by its wedge shape and a hook-l ...

and the palmar surface of the

flexor retinaculum of the hand The flexor retinaculum (transverse carpal ligament, or anterior annular ligament) is a fibrous band on the palmar side of the hand near the wrist. It arches over the carpal bones of the hands, covering them and forming the carpal tunnel. Structu ...

. It is inserted into the medial side of the base of the proximal phalanx of digit V. It is separated from the abductor digiti minimi, at its origin, by the deep branches of the

ulnar artery The ulnar artery is the main blood vessel, with oxygenated blood, of the medial aspects of the forearm. It arises from the brachial artery and terminates in the superficial palmar arch, which joins with the superficial branch of the radial ar ...

and the

ulnar nerve In human anatomy, the ulnar nerve is a nerve that runs near the ulna bone. The ulnar collateral ligament of elbow joint is in relation with the ulnar nerve. The nerve is the largest in the human body unprotected by muscle or bone, so injury is ...

. The flexor digiti minimi brevis is sometimes not present; in these cases, the abductor digiti minimi is usually larger than normal. The flexor digiti minimi brevis is one of three muscles in the

hypothenar muscle The hypothenar muscles are a group of three muscles of the palm that control the motion of the little finger. The three muscles are: * Abductor digiti minimi * Flexor digiti minimi brevis * Opponens digiti minimi Structure The muscles of hypot ...

group. These three muscles form the fleshy mass at the base of the little finger, and are solely concerned with the movement of digit V. The other two muscles that make up the hypothenar muscle group are the abductor digiti minimi and the

opponens digiti minimi The opponens digiti minimi (opponens digiti quinti in older texts) is a muscle in the hand. It is of a triangular form, and placed immediately beneath the palmaris brevis, abductor digiti minimi and flexor digiti minimi brevis. It is one of the ...

. In anatomical position from medial to lateral is the abductor digiti minimi, flexor digiti minimi brevis, and opponens digiti minimi.

Innervation

The flexor digiti minimi brevis, like other

s, is innervated by the deep branch of the

. The ulnar nerve arises from the spinal nerve levels C8-T1. The spinal roots of C8 and T1 then merge to form the lower trunk, anterior division, medial cord, and finally produce the ulnar nerve. The ulnar nerve has a superficial and deep branch, but it is the deep branch that innervates the flexor digiti minimi brevis.

Actions

The flexor digiti minimi brevis flexes the little finger at the metacarpophalangeal joint.

Etymology

The name of this muscle is Latin for the 'short flexor of the little finger'. Note that ''brevis'' is usually included to differentiate it from a ''longus'' muscle of the same name. The flexor digiti minimi longus, however, is not found in the typical human, but instead is a rare anatomical variation.

Additional images

File:Gray219.png, Bones of the left hand. Volar surface. File:Gray417_color.PNG, Cross-section through the middle of the forearm. File:Gray422.png, Transverse section across the wrist and digits. File:Hand dissection 8.jpg, Flexor digiti minimi brevis File:Gray527.png, The radial and ulnar arteries. File:Gray528.png, Ulnar and radial arteries. Deep view. File:Slide16RRR.JPG, Flexor digiti minimi brevis muscle File:Slide6VVV.JPG, Flexor digiti minimi brevis muscle File:Slide5AAAA.JPG, Flexor digiti minimi brevis muscle File:Slide14AAAA.JPG, Flexor digiti minimi brevis muscle File:Slide2BBBB.JPG, Flexor digiti minimi brevis muscle File:Slide11BBBB.JPG, Flexor digiti minimi brevis muscle File:Slide10HHHH.JPG, Flexor digiti minimi brevis muscle File:Slide10IIII.JPG, Flexor digiti minimi brevis muscle File:Slide8OOOO.JPG, Flexor digiti minimi brevis muscle File:Slide1MAI.JPG, Muscles of hand. Cross section.

References

1. 2. Anatomy & Physiology The Unity of Form and Function. Seventh Edition. McGraw Hill. 3. Atkins, S.E, B. Logan, and D. A. McGrouther. "The Deep (Motor) Branch of the Ulnar Nerve: A Detailed Examination of Its Course and the Clinical Significance of Its Damage." The Journal of Hand Surgery. SAGE Journals, 14 Aug. 2008. . {{Authority control Muscles of the upper limb