Which nerve supplies the flexor digitorum brevis muscle?

Which nerve supplies the flexor digitorum brevis muscle?

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

Answer: (A)

Flexor digitorum brevis is an intrinsic muscle of the sole responsible for flexing the middle phalanges of toes 2–5. Its motor supply comes from the medial plantar nerve, a terminal branch of the tibial nerve that innervates most of the medial sole muscles (including abductor hallucis, flexor digitorum brevis, flexor hallucis brevis, and the first lumbrical). Because this muscle’s innervation is specifically through the medial plantar branch, that nerve is the correct answer. The tibial nerve provides the whole trunk that gives rise to the medial and lateral plantar nerves, but the lateral plantar nerve supplies other intrinsic muscles (and not this one), while the common fibular nerve does not innervate plantar intrinsic foot muscles.

Flexor digitorum brevis is an intrinsic muscle of the sole responsible for flexing the middle phalanges of toes 2–5. Its motor supply comes from the medial plantar nerve, a terminal branch of the tibial nerve that innervates most of the medial sole muscles (including abductor hallucis, flexor digitorum brevis, flexor hallucis brevis, and the first lumbrical). Because this muscle’s innervation is specifically through the medial plantar branch, that nerve is the correct answer. The tibial nerve provides the whole trunk that gives rise to the medial and lateral plantar nerves, but the lateral plantar nerve supplies other intrinsic muscles (and not this one), while the common fibular nerve does not innervate plantar intrinsic foot muscles.