Aorta In 25-50% of cases, the inferior portion of the thoracic duct includes a dilated portion called the cisterna chyli. When present, all of the lymph trunks draining the abdomen and lower limbs dump into it, as well as the most inferior intercostal lymph trunks. When it is not present, these trunks simply empty into the thoracic duct. So, the cisterna chyli is a portion of the thoracic duct, and the thoracic duct passes through the diaphragm with the aorta at the T12 level. The inferior vena cava passes through the central tendon of the diaphragm at the T8 level. The esophagus and vagal branches pass through the right crus of the diaphragm at the T10 level. The greater thoracic splanchnic nerves pass through the fibers of the left and right crus.