Hand Muscles Beneath the Skin, Dorsal View

Description

Dorsal skin has been removed to expose the osseous framework of the carpus, metacarpals, and phalanges, with intrinsic muscle bellies occupying the intermetacarpal spaces and tapering into tendinous slips toward the bases of the proximal phalanges. Between adjacent metacarpals, the dorsal interossei form a paired, bipennate mass, lying deep to the extensor tendons and oriented to abduct the index, middle, and ring fingers relative to the third digit. Proximally, the distal row of carpal bones anchors the metacarpal bases, while distally the metacarpophalangeal (MCP) joints sit superficial to the interosseous tendons and dorsal expansions. Functionally, the dorsal view clarifies why intrinsic hand imbalance presents so characteristically at the MCP and interphalangeal joints: the interossei and lumbricals flex the MCP while extending the PIP and DIP via the extensor hood, and loss of that input produces clawing in ulnar and combined ulnar-median neuropathies. Extensor tendon zones over the dorsum also read cleanly in this orientation, which helps when teaching mallet finger (terminal extensor disruption at the distal phalanx) versus boutonniere deformity (central slip injury at the middle phalanx). Small spaces matter here. The intermetacarpal corridors are common entry points for dorsal approaches to metacarpal fixation, and they are also where interosseous compartment swelling can compromise intrinsic function. Use this artwork for upper limb anatomy labs, hand surgery teaching files, or a biomechanics chapter explaining MCP abduction-adduction and the extensor mechanism. It also fits patient-facing materials on extensor tendon injury patterns and postoperative rehab after metacarpal fractures. Anatomical accuracy verified by SciePro's Medical Advisory Board.