Upper limb

Extensor Hood of the Middle Finger

Aponeurosis dorsalis digiti III manus

Origin

Dorsal aspect of the base of the proximal phalanx of the middle finger, where the tendon of extensor digitorum joins the lumbrical and the interossei

Insertion

Base of the middle and distal phalanx of the middle finger

Function

Distributes the pulling force of extensor digitorum and the intrinsic hand muscles across the proximal and distal interphalangeal joints

Innervation

Mixed: radial nerve (extensor digitorum) and median/ulnar nerve (lumbrical and interossei)

Movement & chain

Allows the metacarpophalangeal joint of the middle finger to flex while the interphalangeal joints remain extended, for example when holding a ballpoint pen.

Palpation

Palpable over the dorsal aspect of the 3rd MCP joint and proximal phalanx.

Clinical

Sagittal band rupture (boxer's knuckle) causes painful ulnar subluxation of the extensor tendon during MCP flexion.

Segmental innervation

C7–C8 (radial nerve) & C8–T1 (median nerve)

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