Muscles of the Hand Under the Skin, Posterior View

Description

Reflected just deep to the dorsal skin and fascia, the extensor apparatus spans from the distal forearm across the carpus into the dorsum of the hand, with long tendons running distally over the metacarpals toward the proximal phalanges. Extensor digitorum tendons lie centrally and superficial, while extensor indicis and extensor digiti minimi track more ulnarly toward the index and little fingers, linked by juncturae tendinum proximal to the metacarpophalangeal joints. Between the metacarpals, the dorsal interossei occupy the intermetacarpal spaces as deeper muscle bellies, and the thenar and hypothenar eminences form muscular contours along the radial and ulnar borders even from a posterior perspective. A transverse retaining band at the dorsal wrist corresponds to the extensor retinaculum, keeping the extensor tendons aligned in their osteofibrous compartments. Dorsal hand anatomy matters because extensor tendons sit close to the surface and fail differently than flexors: lacerations often appear deceptively small yet disrupt the sagittal bands or terminal extensor mechanism, producing extensor lag, mallet finger, or boutonniere deformity depending on the level of injury. Compartmental relationships under the extensor retinaculum also ground common diagnoses at the wrist, including De Quervain tenosynovitis in the first dorsal compartment and intersection syndrome more proximally where extensor pollicis brevis and abductor pollicis longus cross the extensor carpi radialis tendons. Surface anatomy, minimal soft tissue coverage, and complex tendon interconnections all show up here. This is high-stakes anatomy. Hand surgeons, emergency clinicians, and therapists can use this artwork to explain dorsal tendon zones, safe incision planning, and postoperative rehabilitation protocols that protect repaired extensor tendons while maintaining glide. It also fits cleanly into upper limb anatomy teaching (gross anatomy, kinesiology, and hand therapy curricula) and figure captions in orthopedic or plastic surgery publications focused on extensor mechanism injury. Anatomical accuracy verified by SciePro's Medical Advisory Board.