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The aorta is the largest artery in the body. It is connected to the left ventricle of the heart and has the job of carrying oxygenated blood from the heart to other parts of the body. The abdominal aorta is the last portion of the aorta and is located in the abdominal cavity. It takes blood from the aorta, through the trunk, and to the abdominopelvic organs and legs.
The left ventricle and thoracic aorta of the heart lead to the abdominal aorta which begins at the diaphragm. This artery then crosses the diaphragm at the level of the T12 vertebrae. From there it descends along the posterior wall of the abdomen in front of the vertebral column, following the natural curvature of the lumbar vertebrae and positioned slightly to the left of the midline of the body. It also lies parallel to the inferior vena cava, which is located to its right.
The abdominal aorta branches into three sets of smaller arteries, becoming narrower as it descends through the abdominal cavity. These three sets are known as the visceral, parietal, and terminal arteries. These branches of the abdominal aorta and their associated vertebral levels are defined as follows. From the vertebral level of T12, the abdominal aorta first branches into the inferior phrenic and celiac arteries (T12), superior mesenteric and middle suprarenal arteries (L1), renal and gonadal arteries (L2), lumbar artery (L1-L4), inferior mesenteric artery (L3), and the median sacral and common iliac arteries (L4). At the L5 level, the artery then splits to form the two common iliac arteries that carry blood to the legs.
The most common ailment involving the abdominal aorta is an abdominal aortic aneurysm (AAA). An aneurysm is a widening (also known as dilation) of a blood vessel due to a weakness in the vessel. At the weak portion, the aneurysm bulges and poses a serious risk of rupture. An AAA is more common in men, particularly those age 60 and older. Approximately 5% of men over the age of 60 suffer from abdominal aortic aneurysms. Risk factors for the development of AAA include cigarette smoking, hypertension, high cholesterol (hypercholesterolemia), and diabetes mellitus. While there are several possible causes of an AAA, the most common cause remains arteriosclerosis, or hardening of the arteries.