Which nerve root primarily innervates the anterior tibialis muscle?

Which nerve root primarily innervates the anterior tibialis muscle?

• A. L3
• B. L5
• C. S1
• D. L4

Answer: (D)

Dorsiflexion of the ankle is carried out by the tibialis anterior, which is innervated by the deep peroneal nerve. The nerve roots that feed this muscle are mainly L4, with some contribution from nearby levels, but L4 provides the strongest drive. That makes L4 the best answer because it aligns with the primary L4 myotome for ankle dorsiflexion. Clinically, testing tibialis anterior function is essentially testing the L4 dorsiflexion pathway. L3 is more linked to knee extension, and S1 to plantarflexion, so they are not the primary roots for this muscle.

Dorsiflexion of the ankle is carried out by the tibialis anterior, which is innervated by the deep peroneal nerve. The nerve roots that feed this muscle are mainly L4, with some contribution from nearby levels, but L4 provides the strongest drive. That makes L4 the best answer because it aligns with the primary L4 myotome for ankle dorsiflexion. Clinically, testing tibialis anterior function is essentially testing the L4 dorsiflexion pathway. L3 is more linked to knee extension, and S1 to plantarflexion, so they are not the primary roots for this muscle.