Which nerve innervates the first lumbrical muscle?

Which nerve innervates the first lumbrical muscle?

• A. Tibial nerve
• B. Medial plantar nerve
• C. Lateral plantar nerve
• D. Common fibular nerve

Answer: (B)

The first lumbrical is innervated by the medial plantar nerve, a branch of the tibial nerve. In the sole, the tibial nerve divides into medial and lateral plantar branches. The medial plantar nerve supplies the muscles on the medial side of the foot, including abductor hallucis, flexor digitorum brevis, flexor hallucis brevis, and the first lumbrical. The remaining lumbricals (and most interossei) receive innervation from the lateral plantar nerve. This pattern mirrors how the hand’s lumbricals are divided between the median and ulnar nerves. Therefore, the medial plantar nerve is the correct innervation for the first lumbrical.

The first lumbrical is innervated by the medial plantar nerve, a branch of the tibial nerve. In the sole, the tibial nerve divides into medial and lateral plantar branches. The medial plantar nerve supplies the muscles on the medial side of the foot, including abductor hallucis, flexor digitorum brevis, flexor hallucis brevis, and the first lumbrical. The remaining lumbricals (and most interossei) receive innervation from the lateral plantar nerve. This pattern mirrors how the hand’s lumbricals are divided between the median and ulnar nerves. Therefore, the medial plantar nerve is the correct innervation for the first lumbrical.