NCS Advantage Practice Exam

Ankle dorsiflexion is driven by the muscles of the anterior compartment, especially the tibialis anterior. These muscles are innervated by the deep peroneal (deep fibular) nerve. This nerve is the direct branch that supplies the dorsiflexors, making it the one most responsible for dorsiflexion strength. The tibial nerve supplies the plantarflexors in the posterior leg, so it’s not the primary driver of dorsiflexion. The common peroneal nerve is a parent nerve that gives rise to the deep peroneal, but it’s the deep branch itself that directly innervates the dorsiflexor muscles. The sciatic nerve is upstream, giving rise to both the tibial and common peroneal nerves, but not directly responsible for dorsiflexion strength.