Dorsal Interosseous Muscle, Posterior View

Description

Arising from the adjacent sides of the metacarpals, the dorsal interosseous muscles occupy the intermetacarpal spaces on the posterior (dorsal) hand, deep to the dorsal fascia and aponeurosis and beneath the extensor tendons as they course distally toward the digits. Each belly sits between the metacarpal shafts, with fibers converging toward tendinous insertions that pass to the bases of the proximal phalanges and into the extensor expansion, positioned between the extensor digitorum tendons centrally and the metacarpal bones deeper. Proximally at the wrist, the extensor retinaculum forms a fibrous roof over the dorsal tendon compartments, keeping the long extensor tendons closely apposed to the carpus. Clear layering matters here. Functionally, this posterior perspective clarifies how the interossei, despite being intrinsic hand muscles, interface with the dorsal digital expansion to influence metacarpophalangeal flexion and interphalangeal extension while also producing finger abduction (DAB). That relationship becomes clinically concrete in ulnar nerve palsy, where denervation of the interossei weakens abduction and contributes to clawing, and in intrinsic tightness where interosseous contracture limits passive PIP flexion when the MCP is extended. For dorsal approaches to the metacarpals, it also helps you anticipate where interosseous muscle bellies will be encountered and retracted when plating fractures or addressing intermetacarpal pathology. Hand anatomy and upper limb modules use this view to teach intrinsic muscle compartments, extensor mechanism anatomy, and tendon retinacular constraints at the wrist. It also suits surgical atlases for dorsal metacarpal exposure, and rehabilitation materials explaining interosseous involvement in ulnar neuropathy, intrinsic tightness testing, or post-fracture stiffness patterns. Anatomical accuracy verified by SciePro's Medical Advisory Board.