Dorsal interossei muscles (hand)

The interossei muscles as a group consist of four palmar (1st 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 3rd phalanx (middle finger).

  • origin: contiguous (adjacent) sides of the five metacarpal bones
  • insertion: extensor hood of their related digit and the base of the proximal phalanx
    • 1st: largest; lateral side of index finger
    • 2nd and 3rd: both attach to either side of 3rd (middle) finger
    • 4th: medial side of 4th (ring) finger
  • innervation: deep branch of the ulnar nerve (C8, T1)
  • action
    • primary: abduction of 2nd, 3rd, and 4th fingers at the MCPJ joints; the 3rd 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

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 2nd, 3rd, and 4th fingers, and their tendons run dorsally to the deep transverse metacarpal ligament.

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

  • Palmar = ADduction
  • Dorsal = ABduction

Upper limb anatomy
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Article information

rID: 51550
Section: Anatomy
Synonyms or Alternate Spellings:

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