Extensor Expansion Hoods as, Posterior View

Description

Dorsal hand anatomy is centered on the extensor expansion (dorsal digital expansion, extensor hood) over the metacarpophalangeal joints, where the extensor digitorum tendon broadens into an aponeurosis that caps the dorsal aspect of each finger. From this posterior perspective, the central slip continues distally to the base of the middle phalanx, while paired lateral bands course along the dorsolateral margins of the proximal phalanx and converge toward the distal phalanx as the terminal tendon. Proximally, the extensor tendons traverse the dorsum of the wrist deep to the extensor retinaculum, then align with the metacarpals before blending into the hood. Clear landmarks. Understanding the extensor expansion matters because it explains how force is distributed across the interphalangeal joints, and why disruption at one level produces characteristic deformity patterns. A tear of the central slip at the proximal interphalangeal joint leads to boutonniere deformity (PIP flexion with DIP hyperextension) as the lateral bands migrate volarly, while terminal tendon failure produces a mallet finger with loss of distal interphalangeal extension. Hand surgeons also reference the sagittal bands at the metacarpophalangeal joint, since rupture can allow extensor digitorum subluxation, often ulnarly, and creates painful snapping with finger flexion and extension. Orthopaedic and hand therapy teaching benefits from this posterior view when explaining tendon balance, splinting principles, and the rationale for central slip versus terminal tendon protocols. It also supports textbook figures on dorsal hand dissection, operative approaches to extensor tendon zones V to VII, and patient education materials for boutonniere and mallet injuries. Anatomical accuracy verified by SciePro's Medical Advisory Board.