Fourth Dorsal Interosseous Muscle Anatomy

Origin: Fourth metacarpals

Insertion: Dorsal extensor expansion

Innervation: Cervical roots): C8-T1

Nerve: Ulnar Nerve

  • The dorsal interosseous muscles are bipennate muscles located between the metacarpals.
  • The first dorsal interosseous muscle inserts into the index proximal phalanx while the 2nd, 3rd, and 4th interossei insert into bone and the extensor aponeurosis. 
  • The dorsal interosseous muscles abduct the fingers, flex the MP joints, and extend the PIP and DIP joints.
  • The interossei muscles are in the deepest layer of hand muscles and contained in a strong fascial compartment.
Diagrams & Photos
  • Note the fourth dorsal interosseous muscle
    Note the fourth dorsal interosseous muscle
  • The fourth dorsal interosseous muscle
    The fourth dorsal interosseous muscle
Key Points
  • The dorsal interosseous muscles pass dorsal to the deep interosseous ligament but volar to the MP joint axis of motion.
  •  The interossei muscles can be damaged by increased compartment pressures associated with intrinsic compartment syndrome.
  • Contracted dorsal interosseous muscles can lead to intrinsic tightness that limits active finger flexion.
Anatomy References
Anatomic Abbreviations
Hand Surgery Resource Anatomy Diagnostic Guide (Chapter)