The truncus arteriosus splits into the ascending aorta and pulmonary artery. Peripheral chemoreceptors are located in the aorta and carotid arteries. Prevention of aortic rupture begins with screening for disease of the aorta. These include aortic aneurysms, dissections, direct trauma to the aorta, surgeries, and atherosclerosis. This part may be compressed between the aorta and SMA causing superior mesenteric artery syndrome. Aortic aneurysms are classified by their location on the aorta. These progressively enlarge until the trunk splits into the aorta and pulmonary arteries. Each organ is supplied by an artery that branches off the aorta. Rupture can also create a connection between the aorta and intestine or inferior vena cava. Structures such as the aorta, inferior vena cava and esophagus pass through the diaphragm. The latter uses continuous wave Doppler to measure blood velocity in the descending thoracic aorta. "" is extensive atherosclerotic calcification of the ascending aorta. The lower esophagus lies behind the heart and curves in front of the thoracic aorta. The aorta, an artery, can be thick. Injuries to the thoracic aorta and heart can also occur.