Interosseous Tendon Slips, Lateral Bands, Posterior View

Description

Arising from the dorsal interossei in the intermetacarpal spaces, the interosseous tendon slips pass distally to join the extensor expansion (dorsal digital hood) over the metacarpophalangeal joints, where they blend with the extensor digitorum communis tendon centrally and feed into the lateral bands on the dorsolateral aspect of each finger. From this posterior, dorsal hand perspective, the lateral bands track along either side of the proximal phalanx and then converge toward the middle phalanx before continuing to the distal phalanx via the terminal extensor tendon. Carpal bones, metacarpals, and phalanges provide the osseous framework, with the radius and ulna proximal to the wrist and the dorsal joint lines of the MCP, PIP, and DIP articulations clearly defined. Orientation is everything. These interosseous contributions to the lateral bands matter because they are the primary route for intrinsic muscles to extend the interphalangeal joints while simultaneously flexing the MCP joints, a relationship that becomes obvious when you trace the fibers across the dorsal hood from proximal to distal. Disruption or imbalance within this extensor mechanism underlies familiar deformities: boutonniere deformity after central slip injury with secondary lateral band volar migration, and swan-neck deformity when lateral bands ride dorsally with PIP hyperextension and DIP flexion. Surgeons repairing extensor tendons in zones III to V, or reconstructing sagittal bands, rely on a clear mental map of where these slips sit relative to the MCP joint and dorsal hood. Hand anatomy and orthopaedic teaching modules will find this posterior view well suited for explaining intrinsic-plus posture, extensor tendon zoning, and the mechanics of the lateral bands during finger extension. It also fits surgical atlases, rehabilitation protocols for extensor mechanism injuries, and patient-facing materials illustrating why splinting targets specific joints in boutonniere and swan-neck patterns. Anatomical accuracy verified by SciePro's Medical Advisory Board.