Dorsal Interosseous Muscles Under the Skin, Posterior View

Description

From a posterior (dorsal) hand view in anatomical position, the four dorsal interosseous muscles occupy the intermetacarpal spaces, their bipennate bellies arising from adjacent metacarpal shafts and converging distally toward the bases of the proximal phalanges and the extensor expansions. Superficial to them, the extensor tendons to digits 2 through 5 course distally over the metacarpals toward the metacarpophalangeal joints, where the dorsal hood spreads laterally to accept interosseous insertions. Proximally at the wrist, the extensor retinaculum forms a transverse fibrous band that restrains the extensor tendons as they pass through the dorsal compartments, maintaining close apposition to the carpus. Finger abduction is the teaching point here, but the anatomy has immediate exam value: wasting of the dorsal interossei produces the characteristic guttering between the metacarpals in ulnar neuropathy, and weakness is tested by resisted abduction of the index (first dorsal interosseous) and little finger. Small joints, tight spaces. This dorsal perspective also clarifies why metacarpal shaft and neck fractures can tether interosseous fascia and why dorsal approaches for metacarpal fixation must respect the extensor tendons and sagittal bands to avoid postoperative extensor lag. Use this artwork in gross anatomy and hand surgery curricula when you need a clean correlation between metacarpal landmarks, the extensor mechanism, and intrinsic muscle bulk, or in clinical skills resources covering ulnar nerve palsy, intrinsic-minus posture, and dorsal interosseous atrophy. It also suits operative atlases and patient education materials explaining dorsal tendon injury zones and the role of the extensor retinaculum at the wrist. Anatomical accuracy verified by SciePro's Medical Advisory Board.