Upper limb

Opponens Digiti Minimi

Musculus opponens digiti minimi

Origin

Hook of the hamate bone and flexor retinaculum

Insertion

Medial border/shaft of the fifth metacarpal bone

Function

Opposes (flexion + rotation) the little finger toward the thumb, deepening the palm during gripping movements

Innervation

Deep branch of the ulnar nerve, C8–T1

Movement & chain

Works together with flexor digiti minimi brevis and abductor digiti minimi as the hypothenar musculature during precision grips and cupping of the hand.

Palpation

Deeply located in the hypothenar eminence, difficult to distinguish from the other hypothenar muscles on superficial palpation.

Clinical

In a lesion of the deep branch of the ulnar nerve (for example in Guyon's canal syndrome), weakness of little finger opposition occurs, reducing the grip function of the hand.

Segmental innervation

Ulnar nerve, C8–T1.

In clinical practice

The little finger opposition test (bringing the little finger against resistance toward the thumb) is used to assess the motor function of the deep branch of the ulnar nerve.

Region in the model

Upper limb