A 24-year-old man loses sensation over the dorsum of the first web space after a knee-high tackle struck the lateral aspect of his leg below the knee. He cannot dorsiflex or evert the foot. Which structure was divided?

• A Superficial peroneal nerve alone
• B Deep peroneal nerve alone
• C Common peroneal nerve at the neck of the fibula ✓
• D Sural nerve

Explanation

Loss of both dorsiflexion (tibialis anterior) and eversion (peroneus longus and brevis) plus sensory loss on the dorsum of the foot localises to the common peroneal nerve where it winds around the fibular neck, its most vulnerable subcutaneous segment. Deep peroneal involvement alone spares eversion; superficial peroneal alone spares dorsiflexion. The sural nerve supplies the lateral border of the foot and ankle, not the first web space.

Reference: Gray's Anatomy, 42nd ed.

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Written and medically reviewed by the StethoPrep medical team.