Aorta

The aorta, the largest artery in the body, carries blood from the heart to the rest of the body.

The aorta rises out of the left ventricle of the heart (the ascending aorta) and then curves down like an upside-down U (aortic arch). It passes through the chest cavity and the abdomen, ending where it branches into the iliac arteries, which provide blood to the pelvis and legs. Multiple branches come off the aorta throughout its course to supply blood to the various organs in its proximity.

The aorta, like all blood vessels, requires nutrients and oxygen for its survival. Blood vessels are constantly being injured and repaired, absorbing and secreting nutrients and chemicals through junctions in their walls.

Physicians classify the aorta and its branches based on their location within the body. The thoracic aorta is the portion of the aorta in the chest (or thorax), which includes the ascending portion, the arch, and the descending portion of the aorta. This section feeds blood vessels in virtually every structure in the upper body, including the brain, arms, lungs, and diaphragm.

The abdominal aorta is the portion of the aorta that passes through the diaphragm into the abdomen. This section feeds blood vessels to the abdominal organs (stomach, liver, spleen, pancreas, kidneys, and bowel). The abdominal aorta eventually branches into the iliac arteries, which provide blood to the pelvis and legs.

The wall of the aorta contains three layers: the intima, media, and adventitia. The layers have significance both in the aorta's function and the pathology that is found when a disease process interferes with the makeup of the wall.

• The intima is made up of cells that line the blood vessel (endothelial cells), creating a smooth surface for the blood flow. This prevents clots (thrombi) from forming along the surface.
• The media is made up of smooth muscle cells that are flexible, allowing the aorta to expand and contract. It is this layer that provides the muscle and strength to the wall of the artery.
• The adventitia provides more strength to the vessel.