Interosseous Lateral Bands, Posterior View

Description

Arising from the interossei along the metacarpal shafts, the interosseous tendon slips join the dorsal digital expansion as lateral bands on the posterior aspect of the digits. Each band tracks distally on either side of the proximal interphalangeal joint, lying lateral to the extensor digitorum tendon and blending with the extensor aponeurosis to continue toward the terminal tendon at the distal phalanx. Carpal bones, metacarpals, and phalanges provide the bony framework beneath the fascia and connective tissue of the dorsal hand, with the bands positioned superficially to the phalanges yet tethered by the extensor hood and related retinacular structures. Orientation is clear. The bands sit lateral, not central. This posterior perspective matters because it isolates the part of the extensor assembly that balances extension across the PIP and DIP joints, the same linkage that fails in common deformity patterns. Disruption or imbalance of the lateral bands and their supporting ligaments underlies boutonniere deformity after central slip injury at the base of the middle phalanx, while volar subluxation of the bands relative to the PIP axis contributes to snapping and progressive imbalance in rheumatoid arthritis. Hand surgeons and therapists also reference these relationships when planning dorsal approaches to the PIP joint and when positioning splints intended to protect the central slip while allowing controlled motion. Ideal for inclusion in gross anatomy and upper limb modules, hand therapy teaching decks, and orthopedic or plastic surgery texts covering extensor mechanism injuries, tendon repair, and deformity correction. It also supports patient education in clinic when explaining why a seemingly small tendon slip can change fingertip extension after injury. Anatomical accuracy verified by SciePro's Medical Advisory Board.