Parkinson’s Disease (PD) Neurological II Practice Exam

Ankle dorsiflexion is produced mainly by the tibialis anterior. This muscle is innervated by the deep peroneal (fibular) nerve, which carries motor fibers from the L4 and L5 spinal roots. So the nerves that mediate dorsiflexion via the tibialis anterior come from L4–L5. The other root levels don’t supply the tibialis anterior motor fibers: L2–L3 largely power hip and knee movements, S2–S3 are more associated with plantar flexion and other lower leg functions, and L5–S1 would involve different muscles rather than the primary dorsiflexor.