Which nerve innervates both the posterior tibialis and the flexor digitorum longus?

Which nerve innervates both the posterior tibialis and the flexor digitorum longus?

• A. Tibial Nerve
• B. Deep Peroneal Nerve
• C. Sural Nerve
• D. Obturator Nerve

Answer: (A)

The muscles in the deep posterior leg share the same motor supply: the tibial nerve. Both the tibialis posterior and the flexor digitorum longus lie in the deep posterior compartment and rely on branches of the tibial nerve to activate their actions—plantar flexion of the foot and, for tibialis posterior, inversion of the foot; for flexor digitorum longus, flexion of the toes and assistance in plantar flexion. The tibial nerve is a branch of the sciatic nerve and runs with the posterior tibial vessels, giving off muscular branches to these muscles before it continues as the plantar nerves in the foot. In contrast, the deep peroneal nerve supplies the anterior compartment muscles, the sural nerve is primarily sensory to the posterior-lateral leg and lateral foot, and the obturator nerve innervates thigh adductors, not leg muscles.

The muscles in the deep posterior leg share the same motor supply: the tibial nerve. Both the tibialis posterior and the flexor digitorum longus lie in the deep posterior compartment and rely on branches of the tibial nerve to activate their actions—plantar flexion of the foot and, for tibialis posterior, inversion of the foot; for flexor digitorum longus, flexion of the toes and assistance in plantar flexion. The tibial nerve is a branch of the sciatic nerve and runs with the posterior tibial vessels, giving off muscular branches to these muscles before it continues as the plantar nerves in the foot. In contrast, the deep peroneal nerve supplies the anterior compartment muscles, the sural nerve is primarily sensory to the posterior-lateral leg and lateral foot, and the obturator nerve innervates thigh adductors, not leg muscles.