Musculi interossei dorsales

The interossei muscles form part of the intrinsic muscles of the hand, and as a group consist of four palmar (1 is often rudimentary) and four dorsal muscles. Collectively, the interossei contribute to abduction and adduction of the fingers and also contribute to flexion of the metacarpophalangeal joints (MCPJ) and extension of the interphalangeal joints (IPJ) through their insertion to the extensor hood. The reference axis through which abduction and adduction occur is the long axis of the 3 phalanx (middle finger).

Summary

• origin: contiguous (adjacent) sides of the five metacarpal bones
• insertion: extensor hood of their related digit and the base of the proximal phalanx
  • 1 and largest: 2 digit dorsal digital expansion and radial side of 2 proximal phalanx
  • 2: 3 digit dorsal digital expansion and radial side of 3 proximal phalanx
  • 3: 3 digit dorsal digital expansion and ulnar side of 3 proximal phalanx
  • 4: 4 digit dorsal digital expansion and ulnar side of 4 proximal phalanx
• innervation: deep branch of the ulnar nerve (C8, T1)
• action
  • primary: abduction of 2, 3, and 4 fingers at the MCPJ joints; the 3 finger can abduct both medially and laterally
  • secondary: contributes to the flexion of MCPJ and extension of the proximal interphalangeal joint and distal interphalangeal joint

Gross anatomy

The dorsal intrinsic muscles of the hand are bipennate and are the most dorsally situated of all intrinsic muscles of the hand. They are associated with abduction of the 2, 3, and 4 fingers, and their tendons run dorsally to the deep transverse metacarpal ligament.

Blood supply

The dorsal interossei are supplied mainly by the dorsal and palmar metacarpal arteries, radial artery, princeps pollicis artery, radialis indicis artery and three perforating branches from the deep palmar arch.

Clinical pearls

The mnemonic “PAD” and “DAB” can be used to help remember the different functions of the two muscle groups.

• Palmar = ADduction
• Dorsal = ABduction

Clinical testing

The first dorsal interosseous muscle can be tested by placing the patient's palm flat on a table and asking the patient to abduct his/her index finger against the examiner's resistance. The muscle belly can be both seen and felt and is a reliable test for the ulnar nerve.

Siehe auch:

• Fingermuskulatur
• Handmuskeln
• Dorsal interossei (foot)
• Musculi interossei palmares