Femoral vein

The femoral vein (v. femoralis) originates from the popliteal vein after the level of adductor hiatus and accompanies the femoral artery through the upper two-thirds of the thigh.

In the lower part of its course it lies lateral to the artery; higher up, it is behind it; and at the inguinal ligament, it lies on its medial side, and on the same plane. It receives numerous muscular tributaries (including the medial and lateral circumflex femoral veins), and about 4 cm. below the inguinal ligament is joined by the deep femoral vein and near its termination it is joined by the great saphenous vein at the saphenofemoral junction.

The femoral vein contains valves that are crucial for preventing retrograde blood flow. These valves are distributed variably, with one to eight valves present within 38 cm distal to the saphenofemoral junction, and up to two valves within 10 cm proximal to this junction

In the femoral triangle, the femoral vein is bounded superiorly by the inguinal ligament, medially by the adductor longus muscle, and laterally by the sartorius muscle. The femoral vein typically lies medial to the femoral artery within the femoral sheath, although anatomical variations can occur.

The diameter of the FV varies along its course, increasing from approximately 6 mm distally to 11 mm proximally near the saphenofemoral junction.