The popliteal vein is a blood vessel found on the rear side of the knee. A unidirectional vessel that transports blood from the lower leg and foot toward the heart, it is fed by the anterior tibial vein and the tibial/peroneal trunk, vessels of the calf. Once it crosses the knee, the popliteal vein becomes the femoral vein, a major vessel of the thigh.
Only a few inches long, the popliteal vein is a paired deep vein of the leg, meaning that the popliteal artery is found next to it carrying blood in the opposite direction. The circulatory system runs on a closed loop, with arteries transporting blood away from the heart and lungs for distribution to the body’s tissues, and veins delivering blood back to the heart. As such, the blood that the arteries transport contains oxygen and various nutrients, while the blood in the veins has been emptied of these substances. In other words, the popliteal vein and other similar vessels return the blood so that it may be refueled, in a sense.
The popliteal vein begins at its lower end by the union of two major vessels: the anterior tibial vein and the tibial/peroneal trunk. Blood from these two vessels flows into the larger popliteal vessel, with the anterior tibial fed by veins on the top of the foot and the tibial/peroneal fed by the posterior tibial vein and the peroneal vein. This convergence of blood flow occurs at the top of the calf, with the lower leg vessels returning blood from nearby leg muscles as well as from the knee joint.
Also draining into the popliteal vein along its course up the knee are several smaller superficial vessels, vessels that lie closer to the skin. The largest of these is the small saphenous vein, which carries blood up the central posterior leg en route from the foot. Other minor vessels run into the popliteal as well, superficial veins returning blood from muscles like the gastrocnemius, soleus, and popliteus, as well as from the skin and soft tissues of this region.
Above, the popliteal vein does not merge with any major vessels. Instead, it continues on its upward course into the thigh as the femoral vein. It becomes the femoral vein upon entering the adductor canal at the bottom of the thigh. Also known as Hunter’s canal, it is a vertical tunnel, triangular when viewed in cross-section, located behind the sartorius muscle and between the vastus medialis and adductor magnus muscles. Here, the paired femoral vein and femoral artery are enclosed.