The abductor minimi digiti - named from its action - is fusiform and somewhat flattened.

Origin

• The lower half of the pisiform bone ;
• the continuation of the tendon of the flexor carpi ulnaris below this bone.

Insertion

• The ulnar side of the base of the first phalanx of the little finger ;
• and the adjacent portion of the aponeurosis of the extensor minimi ligiti.

Structure

Arising by short tendinous fibres, it soon forms a flat fleshy mass I which contracts slightly below, and just before its insertion, having again become tendinous, it is for the most part attached to the first phalanx, but it also sends a Ismail slip backwards to the extensor aponeurosis.

Nerve-supply

From the ulnar nerve through the eighth cervical nerve. It receives small filaments at the outer and deep aspect, usually from the deep palmar division of the ulnar nerve.

Action

To abduct, and at the same time flex, the metacarpo-phalangeal joint of the little finger ; it will also assist, like an interosseous muscle, in the extension of the second and third phalanges.

Relations

Superficially, the hypothenar part of the palmar fascia and the palmaris brevis ; deeply, the flexor brevis and opponens minimi digiti. Upon its radial border are placed the deep palmar branches of the ulnar artery and nerve.