Muscle
Dorsal interossei (hand)
Spread the fingers around the middle-finger axis
High-yield
Finger abduction is measured away from the middle finger. The dorsal interossei also help bend the knuckles while straightening the interphalangeal joints.
Overview
Four muscles occupy the spaces between the metacarpals. Their paired attachments let them spread the index, middle and ring fingers; the middle finger can move to either side.
Reference facts
- Origin
- Facing surfaces of neighboring metacarpals
- Insertion
- Proximal phalanges and extensor expansions: index on its radial side, middle on both sides, ring on its ulnar side
- Action
- Spread digits 2–4; assist MCP flexion and IP extension
- Innervation
- Deep ulnar nerve branch, mainly C8–T1
- Blood supply
- Palmar and dorsal metacarpal arterial branches
Clinical correlation
An ulnar nerve lesion may weaken finger spreading. Loss of first dorsal interosseous bulk can make the space between the thumb and index metacarpals look hollow.
Frequently asked questions
What do the dorsal interossei (hand) do?
Spread digits 2–4; assist MCP flexion and IP extension.
What nerve innervates the dorsal interossei (hand)?
Deep ulnar nerve branch, mainly C8–T1.
Where do the dorsal interossei (hand) attach?
Origin: Facing surfaces of neighboring metacarpals. Insertion: Proximal phalanges and extensor expansions: index on its radial side, middle on both sides, ring on its ulnar side.
What is the blood supply of the dorsal interossei (hand)?
The dorsal interossei (hand) are supplied by the palmar and dorsal metacarpal arterial branches.