Question

Foot drop is caused by injury to which nerve?

• A. Femoral nerve
• B. Tibial nerve
• C. Common peroneal nerve
• D. Sciatic nerve

Hint:

The dorsiflexors are supplied via the common peroneal nerve at the fibular neck.

Answer 1

The Correct Option is C

Step 1: Dorsiflexion of the foot (lifting the front of the foot) is performed by the muscles of the anterior compartment of the leg (tibialis anterior, extensor digitorum longus, extensor hallucis longus), which are supplied by the deep peroneal (fibular) nerve, a branch of the common peroneal nerve.
Step 2: The common peroneal nerve winds around the neck of the fibula, where it is superficial and easily compressed or injured (fibular neck fracture, tight cast, prolonged leg crossing, hip or knee surgery).
Step 3: Injury here paralyses the dorsiflexors and evertors, so the foot drops and the patient develops a high-stepping gait. This makes option (c) correct.
Step 4: The tibial nerve supplies plantar flexors (loss causes a different deficit), the femoral nerve supplies the quadriceps (knee extension), and a complete sciatic injury is proximal and far less common as an isolated cause, so the most specific and common answer is the common peroneal nerve.