Dorsal interossei of hand

The dorsal interossei (Latin: musculi interossei dorsales) are a group of short intrinsic muscles of the hand that are located in the spaces between the metacarpal bones. These four paired muscles extend between the metacarpal bones and proximal phalanges. Together with the lumbricals and palmar interossei muscles, the dorsal interossei belong to the middle group of the hand muscles.

Origin

The dorsal interossei muscles originate from the adjacent sides of the first to fifth metacarpal bones.

Insertion

The dorsal interossei insert on the bases of the second to fourth proximal phalanges and extensor expansions of the second to fourth fingers. The first and second dorsal interossei insert on the lateral (radial) sides of the proximal phalanges 2 and 3, while the third and fourth dorsal interossei attach to the medial (ulnar) sides of the proximal phalanges 3 and 4.

Action

The primary function of the dorsal interossei muscles is to provide the finger abduction at the second to fourth metacarpophalangeal joints. Like the lumbricals of the hand, these muscles also flex the proximal phalanges at the second to fourth metacarpophalangeal joints and extend the middle and distal phalanges at the second to fourth interphalangeal joints.

Innervation

The dorsal interossei of the hand are innervated by the deep branch of the ulnar nerve (C8 - Th1).

Blood supply

The dorsal interossei muscles receive arterial blood supply from the dorsal metacarpal arteries. The first dorsal metacarpal artery is a branch of the radial artery, while the second to fourth dorsal metacarpal arteries arise from the dorsal carpal arch.