Anterior Perspective of the Interossei Muscles

Description

Across the anterior (palmar) aspect of the male hand and wrist, the palmar interossei occupy the deep plane along the metacarpal shafts, arising from the palmar surfaces of metacarpals II, IV, and V and coursing distally toward the bases of the proximal phalanges and extensor expansions. Between the metacarpals, the dorsal interossei can be appreciated as bipennate bellies filling the intermetacarpal spaces, positioned dorsal to the palmar interossei but still readable from a palmar dissection when the superficial palmar aponeurosis and flexor tendons are reflected. Flexor digitorum superficialis and flexor digitorum profundus tendons run distally within their digital synovial sheaths, with lumbricals arising from the profundus tendons on the radial sides and passing anterior to the deep transverse metacarpal ligament toward the extensor hood. Nerve and vessel traces at the wrist and palm align with the median nerve and ulnar nerve in Guyon canal, and with the superficial and deep palmar arterial arches. Fine motor control lives in this layer. The interossei adduct and abduct the digits at the metacarpophalangeal joints and, through their insertion into the extensor apparatus, contribute to MCP flexion with interphalangeal extension, a combination tested in ulnar nerve palsy where interosseous denervation produces clawing of the ring and small fingers and a positive Froment sign. This anterior perspective also supports surgical planning for deep palmar space infections and approaches that must respect the deep branch of the ulnar nerve as it traverses with the deep palmar arch across the bases of the metacarpals. Hand anatomy courses and operative anatomy labs can use this plate to teach the relationship between interossei, lumbricals, flexor tendon sheaths, and the extensor expansion during digit motion. It also fits well in textbooks and patient-facing materials explaining ulnar neuropathy at the wrist versus at the elbow. Anatomical accuracy verified by SciePro's Medical Advisory Board.