The aorta is the largest artery in the body. The aorta begins at the top of the left ventricle, the heart's muscular pumping chamber. The heart pumps blood from the left ventricle into the aorta through the aortic valve. Three leaflets on the aortic valve open and close with each heartbeat to allow one-way flow of blood.
The aorta is a tube about a foot long and just over an inch in diameter. The aorta is divided into four sections:
• The ascending aorta rises up from the heart and is about 2 inches long. The coronary arteries branch off the ascending aorta to supply the heart with blood.
• The aortic arch curves over the heart, giving rise to branches that bring blood to the head, neck, and arms.
• The descending thoracic aorta travels down through the chest. Its small branches supply blood to the ribs and some chest structures.
• The abdominal aorta begins at the diaphragm, splitting to become the paired iliac arteries in the lower abdomen. Most of the major organs receive blood from branches of the abdominal aorta.
Like all arteries, the aorta's wall has several layers:
• The intima, the innermost layer, provides a smooth surface for blood to flow across.
• The media, the middle layer with muscle and elastic fibers, allows the aorta to expand and contract with each heartbeat.
• The adventitia, the outer layer, provides additional support and structure to the aorta.