Dorsal Interossei Muscles, Dorsal View

Description

Arising from the adjacent sides of the metacarpals, the four dorsal interossei occupy the intermetacarpal spaces on the dorsum of the male hand, their muscle bellies centered between the metacarpal shafts and tapering distally toward the bases of the proximal phalanges. From this dorsal perspective, the tendinous expansions can be inferred as they course toward the extensor hood and the proximal phalanx, positioned deep to the extensor digitorum tendons and lateral to the metacarpophalangeal joints. Each muscle is oriented with its bipennate fibers spanning between neighboring metacarpals, creating a symmetric pattern around the longitudinal axis of the third digit. Dorsal interossei matter because they abduct the index, middle, and ring fingers at the metacarpophalangeal joints and, via the extensor mechanism, contribute to proximal interphalangeal and distal interphalangeal extension. That pairing of functions is the teaching point. Clinically, ulnar nerve palsy weakens the interossei, producing impaired finger abduction and the classic ulnar claw pattern from loss of intrinsic balance, and wasting in the intermetacarpal spaces is a visible sign on dorsal inspection; these muscles are also sampled in hand examination with the finger abduction strength test (DAB). Use this artwork in upper limb anatomy labs to differentiate dorsal interossei from palmar interossei, in clinical neuroanatomy modules covering ulnar neuropathy at the elbow or Guyon canal, and in hand surgery or rehabilitation texts discussing intrinsic muscle imbalance after nerve injury. It also supports patient education materials on grip weakness and dorsal hand muscle wasting. Anatomical accuracy verified by SciePro's Medical Advisory Board.