Question

All are seen in injury to the common peroneal nerve except?

• A. Loss of sensation over the sole
• B. Foot drop
• C. Injury to neck of fibula
• D. Loss of dorsiflexion of toe

Hint:

Sole sensation is tibial nerve territory; the common peroneal nerve covers the dorsum of the foot.

Answer 1

The Correct Option is A

Step 1: Recall the function of the common peroneal (fibular) nerve. It supplies the anterior and lateral compartments of the leg, so it controls dorsiflexion of the ankle and toes (deep peroneal nerve) and eversion of the foot (superficial peroneal nerve). A useful aid is PED: the Peroneal nerve Everts and Dorsiflexes.
Step 2: Recall its sensory and anatomical features. It supplies sensation to the anterolateral leg and the dorsum of the foot. It winds superficially around the neck of the fibula, where it is easily injured.
Step 3: Predict the deficits of injury. Loss of dorsiflexion and eversion produces foot drop. Injury commonly occurs at the neck of the fibula. Sensory loss occurs over the dorsum of the foot.
Step 4: Identify the exception. Sensation over the SOLE of the foot is supplied by the tibial nerve (via the medial and lateral plantar nerves), not the common peroneal nerve. Therefore loss of sensation over the sole is a feature of tibial nerve injury, not common peroneal nerve injury.
Conclusion: The exception is loss of sensation over the sole, so the correct answer is option 1.