Dorsal interossei (of hand)

Anatomy

Origin:
Bipennate muscles that arise by two heads from adjacent sides of posterior aspect of the metacarpals.

Insertion:
Extensor hood and base of proximal phalanges of the index, middle and ring fingers.
(It is the middle digit that has two dorsal interossei inserting onto it.)

Key relations:
The radial artery (after passing between the two heads of adductor pollicis) passes between the two heads of the first dorsal interossei as it travels from the dorsal aspect to the palmar aspect of the hand.

Functions

Flexion of the index, middle and ring digits at the metacarpophalgeal joint.
Abducts the index, middle and ring digits at the metacarpophalangeal joint.

Working synergistically with the lumbricals extends the digits at the interphalangeal joints.

Supply

Nerve Supply:
Deep branch of the ulnar nerve (C8, T1).

Blood Supply:
Dorsal and palmar interosseis arteries.

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