The flexor brevis minimi digiti- named from its action - is small and fusiform.

Origin

• The ulnar surface of the hook of the unciform bone ;
• the adjacent part of the front of the anterior annular ligament.

Insertion

The ulnar side of the base of the first phalanx of the little finger.

Structure

Its origin and insertion are by short tendinous fibres, and the rest of the muscle is fleshy.

Nerve-supply

Through the eighth cervical nerve, from the deep branch of the ulnar nerve which sends filaments to the upper part of its deep and ulnar surface.

Action

To flex the first phalanx of the little finger.

Relations

Superficially, the hypothenar part of the palmar fascia, the lower part of the abductor minimi digiti, and the superficial palmar arch ; deeply, the opponens minimi digiti and the fifth metacarpal bone ; and to its radial side lie the flexor tendons of the little finger. This muscle is closely connected with the previous one, from which it is separated above by the deep palmar branches of the ulnar artery and nerve.

Variations

It may fail, or be blended with the abductor or opponens minimi digiti. An accessory slip may come to it from the lower third of the ulna at its inner border, from the tendon of the flexor carpi ulnaris, or the deep fascia of the forearm.