Review Note

When the valves of the perforating veins fail, subcutaneous varicose veins develop. Perforating veins direct venous blood from superficial veins to deeper veins; they have valves that are designed to prevent blood from flowing backwards into the superficial veins. If these valves fail, all of the blood from the superficial veins and some blood from the deep veins is forced into the superficial veins. Because these superficial veins become distended, their valves fail too, and they become varicose. So, this question is asking you to identify the superficial veins on the posterior aspect of the calf.

The lesser or small saphenous vein is a superficial vein that begins as the dorsal venous arch and runs behind the lateral malleolus, up the middle of the back of the leg, and terminates as the popliteal vein in the popliteal fossa. It would be the cause of varicose veins on the posterior lower leg, so it's the answer. The greater saphenous vein is on the medial side of the leg. It also begins as the dorsal venous arch of the foot, and then heads up the leg, anterior to the medial malleolus. At the knee, it goes behind the medial condyle of the femur, and then turns slightly anterior and lateral as it moves up the thigh. It travels through the saphenous opening and drains into the femoral vein.

The femoral vein is a deep vein that drains much of the thigh. It is not a vein that would become varicose. Finally, the dorsal venous arch is located on the dorsum of the foot, and it is where the lesser and greater saphenous veins begin. This is not a common site for varicose veins.