The opponens minimi digiti (= flexor ossis metacarpi minimi digiti) - named from its action - is a triangular fanshaped sheet.

Origin

• From the hook of the unciform bone deeper than the preceding ;
• from the adjacent part of the anterior annular ligament.

Insertion

The whole of the ulna border and part of the head of the fifth metacarpal bone.

Structure

Arising by short tendinous fibres, the fleshy bundles diverge down- wards and outwards, and are inserted by short tendinous fibres.

Nerve-supply

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

Action

To flex the fifth metacarpal bone, and at the same time slightly to adduct it. This movement is observed when the palm is cupped, as when the hand is used as a scoop to lift water to the mouth.

Relations

Superficially, the abductor and the flexor brevis minimi digiti ; and deeply, the interossei of the fourth interspace, and the deep branches of the ulnar artery and nerve.

Variations

It may receive a slip from the deep fascia of the forearm.