Extensor Digitorum Muscle, Posterior View

Description

Dorsal hand anatomy is presented in posterior view, centered on the extensor digitorum muscle as it divides into four tendons coursing distally beneath the extensor retinaculum to digits II through V. Along the dorsum of the metacarpals and proximal phalanges, the tendons flatten into the extensor expansions (dorsal digital expansions), where the central slip passes to the base of the middle phalanx and the lateral bands continue to the distal phalanx. Intertendinous connections (juncturae tendinum) link adjacent extensor digitorum tendons over the dorsum of the hand, while the metacarpals and phalanges form the bony framework deep to the fascia and tendon sheaths. Color coding differentiates muscle bellies from tendon and selected vessels, with the fascial planes kept clean for teaching. Posterior visualization of the extensor digitorum and its tendon network matters because finger extension is not a single tendon-to-bone event, it is a coordinated mechanism mediated by the extensor hood and the balance between central slip and lateral bands. Mallet finger reflects disruption at the terminal tendon over the distal interphalangeal joint, whereas boutonniere deformity follows central slip injury at the proximal interphalangeal level with volar migration of the lateral bands. This dorsal dissection also supports procedural planning, including tendon repair and transfer work, where tendon caliber, juncturae tendinum, and the constraint of the extensor retinaculum guide incision placement and postoperative splinting strategy. Small landmarks. Big consequences. Use this illustration in upper limb gross anatomy, hand surgery teaching files, and rehabilitation or orthotics materials that explain extensor tendon zones, dorsal approaches to metacarpals and phalanges, and mechanisms of extension lag after laceration. It also fits medical publishing needs for chapters on dorsal hand anatomy, extensor tendon injury patterns, and surgical repair principles in an adult male specimen context. Anatomical accuracy verified by SciePro's Medical Advisory Board.