Dorsal Interosseous Muscles, Posterior View

Description

Seen from the posterior aspect of the male hand, four dorsal interosseous muscles occupy the intermetacarpal spaces, each bipennate belly arising from adjacent metacarpal shafts and filling the dorsum between the second through fifth metacarpals. Their tendons course distally toward the bases of the proximal phalanges and blend with the extensor expansions, lying deep to the extensor digitorum tendons that run centrally over the metacarpophalangeal joints. Semi-transparency reveals the metacarpals and phalanges as a grey framework beneath the red-pink intrinsic musculature, while fine dorsal ligaments and segments of synovial sheath outline the low-friction pathways of the extensor mechanism. Orientation is clear. Radial structures sit laterally at the index side, ulnar structures medially at the little finger side. Dorsal interossei are prime abductors of the digits (DAB) and, through their insertion into the extensor hood, they also contribute to metacarpophalangeal flexion with interphalangeal extension, a coupling that students often miss when only the palmar view is taught. This posterior angle offers the clearest perspective on why the first dorsal interosseous becomes a visible contour in pinch grip and why wasting here is an early, clinically obvious sign of ulnar neuropathy at the elbow or Guyon canal. Hand surgeons also use these intermetacarpal corridors when planning dorsal approaches for metacarpal fracture fixation, where preserving the dorsal interosseous bellies and the extensor tendons limits postoperative stiffness. Ideal for upper-limb anatomy courses, hand therapy manuals, and operative teaching files covering intrinsic muscle balance, extensor apparatus mechanics, and ulnar nerve motor examination, this asset also supports patient-facing education on interosseous atrophy and functional loss of finger abduction-adduction. Anatomical accuracy verified by SciePro's Medical Advisory Board.