Lymph Vessels of the Fascia Cruris

A small number of the lymph vessels of the fascia cruris drain to the popliteal lymph node, though most drain to the medial iliac lymph node and some to the deep inguinal and medial femoral lymph nodes, when present. However, the lymph vessels draining to the medial iliac lymph node take very different paths.

a. Medial side of the lower leg

Almost all the lymph vessels of the fascia cruris on the medial side of the lower leg join the great saphenous vein and ascend with it to the femoral canal and then to the medial iliac lymph node.

b. Lateral side of the lower leg

i. Proximal (Upper) Half

From this part of the fascia, the lymph vessels run obliquely caudodorsally, penetrating either the aponeurosis (endaponeurosis) or the cranial border of the M. biceps, and enter the popliteal fossa between the M. gastrocnemius lateralis and the stifle joint capsule. From there, the vessels course to the femoral canal where they join the lymph vessels described in A, above.

ii. Distal (Lower) Half

From this part of the fascia, some of the lymph vessels join the small saphenous vein and rise with it to drain to the popliteal lymph node, whereas others travel under the fascia and more deeply between the M. extensor digitalis longus and the peroneus muscles, and accompany the anterior tibial artery and vein to the popliteal fossa, where they join with the lymph vessels described in A, above, ascending with them to the medial iliac lymph node.

Some of the lymph vessels of the fascia of the cranial border of the lower leg join the lymph vessels on the lateral side, and some join the lymph vessels on the medial side. If a deep inguinal lymph node is present, some of the aforementioned lymph vessels ascending in the femoral canal will drain to it. If a medial femoral lymph node is present, some of the lymph vessels accompanying the great saphenous vein will drain to it. Rarely, some of the lymph vessels that usually ascend in the femoral canal show somewhat different behaviour, wherein they travel more deeply between the M. pectineus and adductor muscles towards the deep femoral artery, and accompany this artery before then rejoining the other lymph vessels of the femoral canal in the abdominal cavity.