Foot drop is caused by inability to dorsiflex due to injury of which nerve?

Foot drop is caused by inability to dorsiflex due to injury of which nerve?

• A. Common fibular nerve
• B. Tibial nerve
• C. Sural nerve
• D. Median nerve

Answer: (A)

Foot drop happens when the muscles that lift the front of the foot can’t contract, which are the anterior compartment muscles like tibialis anterior and the Extensor digitorum longus. Those muscles get their nerve supply from the deep branch of the common fibular (peroneal) nerve. If the common fibular nerve is injured, dorsiflexion is lost and foot drop results. The tibial nerve controls the opposite action—plantarflexion via the posterior leg muscles—so its injury wouldn’t typically cause loss of dorsiflexion. The sural nerve is sensory, not motor, so damage would affect sensation rather than movement. The median nerve serves the forearm and hand, not the leg, so it wouldn’t cause foot drop.

Foot drop happens when the muscles that lift the front of the foot can’t contract, which are the anterior compartment muscles like tibialis anterior and the Extensor digitorum longus. Those muscles get their nerve supply from the deep branch of the common fibular (peroneal) nerve. If the common fibular nerve is injured, dorsiflexion is lost and foot drop results.

The tibial nerve controls the opposite action—plantarflexion via the posterior leg muscles—so its injury wouldn’t typically cause loss of dorsiflexion. The sural nerve is sensory, not motor, so damage would affect sensation rather than movement. The median nerve serves the forearm and hand, not the leg, so it wouldn’t cause foot drop.