Upper limb

Third Palmar Interosseous

Musculus interosseus palmaris III

Origin

Radial side of the 5th metacarpal bone

Insertion

Radial side of the base of the proximal phalanx of the little finger, with extension into the extensor hood

Function

Adduction of the little finger toward the middle finger axis

Innervation

Ulnar nerve, deep (motor) branch

Movement & chain

Together with the other palmar interossei, pulls the little finger toward the middle finger axis, for example when squeezing extended fingers together.

Palpation

Deep along the radial aspect of the 5th metacarpal within the hypothenar region.

Clinical

Adducts the little finger toward the ring finger; tested clinically by card/paper grip between digits 4 and 5.

Segmental innervation

Ulnar nerve, C8-T1.

In clinical practice

Focus on hand function and edema prevention; ensure IV cannulas and splints maintain functional hand position to prevent joint contractures.

Region in the model

Upper limb