The superficial veins of the lower limbs consist of two main superficial veins, the great saphenous vein and the small saphenous vein. The great saphenous vein and the small saphenous vein are divided into numerous collateral veins, of which the great saphenous vein has five main branches, which are the lateral saphenous vein, the medial saphenous vein, the abdominal wall saphenous vein, the pubic saphenous vein, and the circumflex iliac saphenous vein. The great saphenous vein originates from the medial aspect of the ankle, passes through the medial aspect of the calf, runs along the inner and posterior aspect of the popliteal fossa, and collects the five branches of the superficial vein in the groin of the medial thigh, and flows into the femoral vein through the saphenous vein fissure, which is the longest subcutaneous vein in the human body. The small saphenous vein originates from the dorsal venous arch of the foot and travels posterior to the lateral aspect of the ankle along the posterior lateral border of the calf to reach the upper part of the calf, where it crosses the deep fascia and injects into the popliteal vein. Branches of both combine with each other to form a network of superficial veins. The two are connected to the deep veins by means of the traffic veins (also called traffic branches). There is one traffic vein in the upper and middle thighs and one at the knee. Below the knee, there are usually three to four traffic veins, mostly located at the inner ankle and the middle of the calf.