Lymph Vessels of the Peritoneum
The lymph vessels of the peritoneum drain to the cranial lumbar aortic lymph nodes, the medial iliac lymph nodes, the deep inguinal lymph nodes, the sternal lymph nodes, the left hepatic lymph node, and the gastric lymph node. The lymph vessels from most of the caudal half of the peritoneum run on each side towards the medial iliac lymph node, gradually merging into 2 to 3 vessels, which then turn towards the deep circumflex iliac artery and vein, accompanying them to the aforementioned lymph node. Only the lymph vessels of the peritoneum on the caudal half of the ventral abdominal wall join the caudal epigastric artery and vein as they run towards the inguinal canal, where they join with the external iliac artery and vein to run to the medial iliac lymph node. If a deep inguinal lymph node is present, some of these lymph vessels drain to it.
Most of the lymph vessels from the cranial half of the peritoneum turn in a dorsal direction towards the A. and V. lumboabdominalis, accompanying these vessels to drain into the cranial lumbar aortic lymph node. Only the lymph vessels from the part of the cranial half located on the ventral abdominal wall and on the ventral part of the lateral abdominal wall drain to the sternal lymph node; these lymph vessels enter the thoracic cavity at the attachment of the diaphragm to the xiphoid cartilage and accompany the internal mammary artery and vein to the aforementioned lymph node. Some of the lymph vessels from the peritoneum of the part of the lateral and ventral abdominal walls adjoining the diaphragm run to the diaphragm and join the diaphragmatic lymph vessels, flowing with them not only to the cranial lumbar aortic lymph node and sternal lymph node, but also the middle tracheobronchial lymph node, the gastric lymph node, the left hepatic, and even to the splenic lymph nodes.
The following peritoneal lymph vessel behaviours have been directly observed: lymph vessels that either run subperitoneally on the diaphragm to drain to the cranial lumbar aortic lymph node or drain to the sternal lymph node; lymph vessels that pass through the diaphragm, run subpleurally on it and drain to the cranial lumbar aortic and sternal lymph nodes; and lymph vessels that join those of the diaphragm and drain to the left hepatic and gastric lymph nodes. Peritoneal lymph vessels that join the diaphragmatic lymph vessels and drain to the splenic and middle tracheobronchial lymph nodes could not be directly demonstrated, but there is no doubt that such lymph vessels are present. Sometimes they simply may not fill with the injected solution, and often the injection takes too long to perform.