 The great saphenous vein , ( GSV ) a superficial vein , is the longest vein in the body . It has its origin in the dorsal venous arch of the foot , a superficial vein which connects the small saphenous vein with the GSV . It travels up the leg and medial side of the thigh to reach the groin , where it drains into the common femoral vein . Along the length of the GSV , it receives numerous tributaries , ( from the subcutaneous layer ) and drains into the deep veins via the perforator veins . When seen in a scan , the GSV and the Giacomini vein , together with the accessory saphenous vein ( ASV ) , form an image resembling an eye which is referred to as the " eye sign " or " eye image " . . All veins which are between the skin and the superficial fascia are tributaries and all veins which cross the deep fascia to join the deep venous system are perforator veins . 
