The popliteal lymph nodes, small in size and some six or seven in number, are embedded in the fat contained in the

popliteal fossa The popliteal fossa (also referred to as hough, .html" ;"title="/sup>">/sup> or kneepit in analogy to the cubital fossa) is a shallow depression located at the back of the knee joint. The bones of the popliteal fossa are the femur and the tibia ...

, sometimes referred to as the 'knee pit'. One lies immediately beneath the popliteal fascia, near the terminal part of the

small saphenous vein The small saphenous vein (also short saphenous vein or lesser saphenous vein) is a relatively large superficial vein of the posterior leg. Structure The origin of the small saphenous vein, (SSV) is where the dorsal vein from the fifth digit (sma ...

, and drains the region from which this vein derives its tributaries, such as superficial regions of the posterolateral aspect of the leg and the plantar aspect of the foot. Another is between the

popliteal artery The popliteal artery is a deeply placed continuation of the femoral artery opening in the distal portion of the adductor magnus muscle. It courses through the popliteal fossa and ends at the lower border of the popliteus muscle, where it branche ...

and the posterior surface of the

knee-joint In humans and other primates, the knee joins the thigh with the leg and consists of two joints: one between the femur and tibia (tibiofemoral joint), and one between the femur and patella (patellofemoral joint). It is the largest joint in the h ...

. It receives afferents from the knee-joint, together with those that accompany the genicular arteries. The others lie at the sides of the popliteal vessels, and receive, as efferents, the trunks that accompany the anterior and posterior tibial vessels. The efferents of the popliteal lymph nodes pass almost entirely alongside the

femoral vessels The femoral vessels are those blood vessels passing through the femoral ring into the femoral canal thereby passing down the length of the thigh until behind the knee. These large vessel are the: * Femoral artery (also known in this location a ...

to the deep inguinal lymph nodes, but a few may accompany the

great saphenous vein The great saphenous vein (GSV, alternately "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 lower limb, returning blood from the foot, leg and thi ...

, and end in the glands of the superficial subinguinal group. The flow of

lymph Lymph (from Latin, , meaning "water") is the fluid that flows through the lymphatic system, a system composed of lymph vessels (channels) and intervening lymph nodes whose function, like the venous system, is to return fluid from the tissues ...

from the legs towards the heart is the result of the ''calf pump''– during

walking Walking (also known as ambulation) is one of the main gaits of terrestrial locomotion among legged animals. Walking is typically slower than running and other gaits. Walking is defined by an ' inverted pendulum' gait in which the body vaults ...

the calf muscle contracts, squeezing lymph out of the leg via the

lymphatic vessels The lymphatic vessels (or lymph vessels or lymphatics) are thin-walled vessels (tubes), structured like blood vessels, that carry lymph. As part of the lymphatic system, lymph vessels are complementary to the cardiovascular system. Lymph vessel ...

. When the muscle relaxes, valves in the vessels shut preventing the fluid from returning to the lower extremities.

References

External links

Image at cwc.net
Lymphatics of the lower limb {{Portal bar, Anatomy