Lumbricals innervation pattern?

Lumbricals innervation pattern?

• A. Lateral 2 - median n; Medial 2 - ulnar n deep branch
• B. Lateral 2 - ulnar n; Medial 2 - median n
• C. All four - median n
• D. All four - ulnar n

Answer: (A)

Lumbricals in the hand have split innervation: the lateral pair are supplied by the median nerve (via its recurrent branch), while the medial pair are supplied by the deep branch of the ulnar nerve. This arrangement aligns with their origins on the flexor digitorum profundus tendons, where the radial (lateral) slips are associated with median nerve supply and the ulnar (medial) slips with the ulnar nerve. The lumbricals flex the metacarpophalangeal joints and extend the interphalangeal joints, so damage to the median nerve primarily affects the lateral two lumbricals, whereas damage to the deep branch of the ulnar nerve affects the medial two.

Lumbricals in the hand have split innervation: the lateral pair are supplied by the median nerve (via its recurrent branch), while the medial pair are supplied by the deep branch of the ulnar nerve. This arrangement aligns with their origins on the flexor digitorum profundus tendons, where the radial (lateral) slips are associated with median nerve supply and the ulnar (medial) slips with the ulnar nerve. The lumbricals flex the metacarpophalangeal joints and extend the interphalangeal joints, so damage to the median nerve primarily affects the lateral two lumbricals, whereas damage to the deep branch of the ulnar nerve affects the medial two.