Extensor Indicis Muscle, Posterior View

Description

Arising from the posterior surface of the ulna in the distal forearm, the extensor indicis muscle belly tapers into a long tendon that passes deep to the extensor retinaculum and courses distally on the dorsum of the wrist toward the index finger. Across the carpus and metacarpus, the tendon lies medial (ulnar) to the extensor digitorum tendon slip to digit II before blending into the dorsal extensor expansion over the proximal phalanx. Surrounding osteology is rendered in detail, including the carpal bones, metacarpals, and the phalanges with their interphalangeal and metacarpophalangeal joints shown in posterior orientation. Clear bony landmarks. Independent index finger extension matters in both clinical exam and tendon surgery, and extensor indicis is the workhorse donor for extensor pollicis longus reconstruction after rupture in the setting of distal radius fracture or rheumatoid tenosynovitis. This posterior view clarifies why the tendon must be tracked beneath the retinaculum and into the extensor hood, where adhesions, sagittal band injury, or iatrogenic tethering can limit isolated index extension. It also supports teaching of tendon compartment anatomy at the wrist, where extensor indicis shares the 4th dorsal compartment with extensor digitorum. Use this artwork in upper-limb anatomy courses to contrast extrinsic digital extensors with intrinsic hand musculature, and in surgical education materials covering tendon transfer planning, dorsal wrist approaches, and postoperative motion protocols. It also suits radiology or sports medicine publications that correlate dorsal wrist pain with extensor compartment pathology and tenosynovitis patterns. Anatomical accuracy verified by SciePro's Medical Advisory Board.