Popliteal lymph nodes

Nodi lymphoidei poplitei

Lymphatic & immuneLymphaticsLegLeft and right

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What it is

Five to seven small nodes buried in the fat of the hollow behind the knee, around the popliteal vessels and at the end of the small saphenous vein. Each node is a bean-shaped filter 5-15 mm long with a fibrous capsule, an outer cortex of B-cell follicles, a T-cell paracortex and an inner medulla. Several afferent lymphatics enter its convex surface; one or two efferents leave at the hilum.

Function

Drain the outer side of the foot and the calf (the small saphenous territory) and the deep tissues of the leg, sending lymph up along the femoral vessels to the deep inguinal nodes.

Size

5-7 nodes of 3-8 mm

Clinical note

Rarely palpable; they enlarge with infections of the heel and lateral foot and with melanoma of the lower leg.