Upper limb

Second Palmar Interosseous

Musculus interosseus palmaris II

Origin

Radial side of the 4th metacarpal bone

Insertion

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

Function

Adduction of the ring finger toward the middle finger axis

Innervation

Ulnar nerve, deep (motor) branch

Movement & chain

Together with the other palmar interossei (PAD), pulls the ring finger toward the middle finger axis, functionally used when squeezing extended fingers together.

Palpation

Deep along the radial surface of the 4th metacarpal; not directly palpable.

Clinical

Adducts the ring finger toward the middle finger; paralyzed in ulnar nerve entrapment at Guyon's canal.

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