  the great saphenous vein (gsv), previously also called the long saphenous vein, is a large, subcutaneous, superficial vein of the leg. it is the longest vein in the body running along the length of the leg. the terms "safaina" (greek, meaning "manifest," "to be clearly seen") and "safoon" (hebrew, meaning "hidden/covered") have both been claimed as the origin for the word "saphenous." ==structure== the gsv originates from where the dorsal vein of the first digit (the large toe) merges with the dorsal venous arch of the foot. after passing anterior to the medial malleolus (where it often can be visualized and palpated), it runs up the medial side of the leg. at the knee, it runs over the posterior border of the medial epicondyle of the femur bone. the great saphenous vein then courses anteriorly to lie on the anterior surface of the thigh before entering an opening in the fascia lata called the saphenous opening. it forms an arch, the saphenous arch, to join the common femoral vein in the region of the femoral triangle at the sapheno-femoral junction.  ===tributaries=== at the ankle it receives branches from the sole of the foot through the medial marginal vein; in the lower leg it anastomoses freely with the small saphenous vein, communicates by perforator veins (cockett perforators) with the anterior and posterior tibial veins and receives many cutaneous veins; near the knee it communicates with the popliteal vein by the boyd perforator, in the thigh it communicates with the femoral vein by perforator veins (dodd perforator) and receives numerous tributaries; those from the medial and posterior parts of the thigh frequently unite to form a large accessory saphenous vein which joins the main vein near the sapheno-femoral junction.{{cite book|title=principles of venous hemodynamics|author=franc
Veins_of_the_lower_limb