What is the nerve pattern for the lumbricals in the hand?

What is the nerve pattern for the lumbricals in the hand?

• A. The radial nerve supplies all lumbricals.
• B. Lateral two lumbricals (index and middle) — median nerve; medial two lumbricals (ring and little) — ulnar nerve
• C. The median nerve supplies all lumbricals.
• D. Lateral two lumbricals — ulnar nerve; medial two lumbricals — median nerve

Answer: (B)

Think about how the hand’s intrinsic muscles are organized by nerve supply. The lumbricals flex the metacarpophalangeal joints and extend the interphalangeal joints, so their innervation follows their position in the palm. The two on the thumb side (lateral) are supplied by the median nerve through its recurrent branch, since they originate from the tendons of the flexor digitorum profundus to the index and middle fingers. The two on the pinky side (medial) are supplied by the ulnar nerve via its deep branch, coming from the tendons of the FDP to the ring and little fingers. Therefore, the lateral two lumbricals are median-nerve–innervated, and the medial two lumbricals are ulnar-nerve–innervated. This pattern aligns with how the median and ulnar nerves service the intrinsic hand muscles.

Think about how the hand’s intrinsic muscles are organized by nerve supply. The lumbricals flex the metacarpophalangeal joints and extend the interphalangeal joints, so their innervation follows their position in the palm. The two on the thumb side (lateral) are supplied by the median nerve through its recurrent branch, since they originate from the tendons of the flexor digitorum profundus to the index and middle fingers. The two on the pinky side (medial) are supplied by the ulnar nerve via its deep branch, coming from the tendons of the FDP to the ring and little fingers. Therefore, the lateral two lumbricals are median-nerve–innervated, and the medial two lumbricals are ulnar-nerve–innervated. This pattern aligns with how the median and ulnar nerves service the intrinsic hand muscles.