Leave the kidneys in place. Dissection of the kidneys will be completed later. The connective tissue associated with the inferior vena cava and aorta contains lymph nodes, lymph vessels and the aortic nerve plexus. Lymph from the lower extremity, pelvis, and body wall drains into the lumbar trunk on the same side of the body. At the region of the superior mesenteric artery, the intestinal trunk, which is formed by efferent lymphatics from the superior mesenteric and celiac nodes, usually joins the left lumbar trunk before the two lumbar trunks unite.
Considerable variation occurs in the configuration of the lymph trunks.
It is advantageous to leave further dissection of lymphatics until the crura of the diaphragm are cleaned. The inferior vena cava is formed by the joining of the two common iliac veins dorsal to the right common iliac artery at the caudal level of the fourth lumbar vertebra. It ascends on the right side of the aorta to the level of the renal arteries where it deviates slightly toward the central tendon of the diaphragm, whereas the aorta passes between the two crura of the diaphragm. The inferior vena cava has a complex developmental history and many variations, some of which are usually present in the cadavers dissected each year. Look at other dissections to see some of these variations.