The distal pa of the lesser saphenous vein was mobilized for grafting. Following the operation, the patient complained of numbness on the distal lateral side of the leg and the lateral side of the foot. What nerve was damaged during the operation?

The sural nerve runs with the lesser saphenous vein, posterior to the lateral malleolus and up the back of the leg. It provides cutaneous innervation to the skin of the posterior surface of the lower leg and the skin of the lateral side of the foot. So, both the case history and the symptoms point to a sural nerve injury. The deep fibular nerve is not a major nerve for cutaneous innervation--it innervates the muscles of the anterior compament of the leg as well as the web of skin between the 1st and 2nd toe. If this nerve was injured, a patient would not have a distinct loss of cutaneous sensation (except in that small web of skin). Instead, the prominent symptom would be "foot drop". The posterior femoral cutaneous nerve provides sensory innervation to the skin of the lower buttock and posterior thigh. The saphenous nerve travels with the great saphenous vein and provides cutaneous innervation to the medial leg and foot. Finally, the superficial fibular nerve provides sensory innervation to the anterior surface of the distal third of the leg and the dorsal surface of the foot.