Lymphatics of the Limb - Horse Anatomy

Thoracic Limb

Lymph from the superficial and proximal regions of the thoracic limb drains to the superficial cervical lymph centre. Other regions of the limb all drain to the axillary lymph centre, which is located within the axilla. The axillary lymph centre is comprised of the proper axillary lymph node as well as an accessory axillary lymph node and lymph node of the first rib. In the horse, there may be another group of lymph nodes from this centre located on the medial aspect of the elbow.

Pelvic Limb

Lymph from the pelvic limb drains mainly to the iliosacral lymph centre, which is comprises the following:

• Medial iliac lymph nodes: These are located at the point where the aorta splits in the pelvic region. They drain the pelvic viscera and pelvic limbs.
• Lateral iliac lymph nodes: Not always present, located at the bifurcation of the deep circumflex ilial artery.
• Internal iliac lymph nodes: Located adjacent to the internal iliac artery, drain adjacent regions
• Sacral lymph nodes: Located ventral to the sacrum, drains the adjacent region
• Anorectal lymph nodes: Located lateral to the rectum, drains the adjacent region

Some lymph from the thigh and the popliteal lymph nodes drains to the iliofemoral lymph centre, which subsequently drains to the medial iliac lymph nodes. The iliofemoral lymph centre is located along the course of the femoral continuation of the external iliac artery.

The ischial lymph centre receives lymph from the caudal rump and thigh, which subsequently drains to the iliosacral lymph node. The ischial lymph centre is located on the lateral aspect of the sacrosciatic ligament, adjacent to the ischial tuberosity.

The popliteal lymph centre is comprised of the superficial and deep poplitieal lymph nodes. It is located caudal to the stifle and drains the distal limb. Lymph from this centre subsequently flows to the deep inguinal lymph nodes.

References

• Konig, H.E., Liebich, H.G. Veterinary Anatomy of Domestic Mammals: Textbook and Colour Atlas (2009), Schattauer