Which nerve injury presents with foot drop and sensory loss over the first dorsal web space?

• A. Tibial nerve injury
• B. Sural nerve injury
• C. Common peroneal nerve injury
• D. Deep peroneal nerve injury

Answer: (D)

Foot drop arises from loss of dorsiflexion, which is carried out by the anterior compartment muscles innervated by the deep peroneal nerve. The deep peroneal nerve also provides sensation to the first dorsal web space between the hallux and the second toe. When this nerve is injured, you get both the motor deficit (inability to dorsiflex, i.e., foot drop) and the precise sensory loss in that first web space. Other nerves don’t produce this exact combination: a tibial nerve injury mainly affects plantarflexion and sole sensation; a sural nerve injury alters lateral foot sensation without dorsiflexion loss; a common peroneal nerve injury can cause foot drop but the sensory loss pattern is broader on the dorsum and not specifically the first web space. Hence, deep peroneal nerve injury best explains both findings.