Dorsal interossei

Dorsal interossei are a group of muscles in the hand. They are four in number and are situated in the back of the hand. They are bipenniform muscles and are placed between the metacarpal bones. The dorsal interossei muscles are responsible for the abduction of the fingers and contribute to the flexion of the fingers at the metacarpophalangeal joints and extension at the interphalangeal joints.

Structure

The dorsal interossei muscles originate from the adjacent sides of the metacarpal bones, and are inserted into the bases of the first phalanges and the extensor expansions of the fingers. The first (or preaxial) dorsal interosseous muscle is larger than the others, and its insertion accompanies that of the extensor indicis muscle.

Function

The primary function of the dorsal interossei muscles is to abduct the fingers away from the axial line. Additionally, they also assist in flexion at the metacarpophalangeal joints and extension at the interphalangeal joints.

Clinical significance

Injury or damage to the dorsal interossei muscles can lead to a loss of finger abduction, which can significantly impact hand function. This can occur due to peripheral nerve injuries, such as a claw hand deformity, where the metacarpophalangeal joints are hyperextended and the interphalangeal joints are flexed.

See also

• Hand anatomy
• Metacarpal bones
• Interossei muscles
• Claw hand