A medial femoral lymph node (Figures 13: t; 37: e) has not been previously described, and is uncommon: it was found only 5 times in 40 examined cases. It was found once on both sides, once on the left side, and 3 times on the right side. It is a small lymph node, often no more than 1 cm long in large dogs and usually only 2 to 3 mm in length in small dogs.

It is found on the medial side of the thigh, at the distal end of the femoral canal, medial to the distal end of the M. pectineus or M. adductor, between the M. sartorius and M. gracilis, and in the fatty connective tissue under the fascia on the caudal border of the femoral vessels.

Afferent drainage

The medial femoral lymph node drains lymph vessels from the skin on the medial side of the stifle joint, the lower leg and the foot, the fascia cruris, the stifle and tarsal joints, the patella, the tibia, the tarsal and metatarsal bones, the Achilles, the superficial and deep flexor tendons, the Mm. interossei pedis and M. extensor digitalis pedis brevis, as well as the efferent vessels of the popliteal lymph node. However, it is not uncommon for the described lymph vessels to not enter the medial femoral lymph node even when it is present.

Efferent drainage

One to 2 efferent vessels arise from the lymph node and ascend within the femoral canal to drain into the medial iliac lymph node (Figures 37: e’; 27: 11). A deep inguinal lymph node was not present in the examined cases.

Clinical Notes