Main artery in the human body.
The aorta is the largest artery in the body. Arteries are vessels that carry blood away from the heart. The aorta arises from the left ventricle of the heart, forms an arch, then extends down to the abdomen, where it branches off into two smaller arteries. The aorta carries and distributes oxygen rich blood to all arteries. Most major arteries branch off from the aorta, with the exception of the main pulmonary artery. Aortic arch. The aortic arch is the portion of the main artery that bends between the ascending and descending aorta. It leaves the heart and ascends, then descends back to create the arch. The aorta distributes blood from the left ventricle of the heart to the rest of the body All rights reserved. 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: Aorta: The largest artery in the body, the aorta arises from the left ventricle of the heart, goes up (ascends) a little ways, bends over (arches), then goes down (descends) through the chest and through the abdomen to where ends by dividing into two arteries called the common iliac arteries that go to the legs.  Aortic dissection occurs when a tear in the outer wall of the aorta causes blood to flow between the layers of the wall of the aorta, forcing the layers apart.  An aortic aneurysm (say a-OR-tik AN-yuh-rih-zum) is a bulge in a section of the aorta, the body's main artery. The aorta carries oxygen-rich blood from the heart to the rest of the body. Because the section with the aneurysm is overstretched and weak, it can burst.  The aorta (/eɪˈɔrtə/) is the main artery in the human body, originating from the left ventricle of the heart and extending down to the abdomen, where it splits into two smaller arteries (the common iliac arteries). The aorta distributes oxygenated blood to all parts of the body through the systemic circulation. One way of classifying a part of the aorta is by anatomical compartment, where the thoracic aorta (or thoracic portion of the aorta) runs from the heart to the diaphragm. The aorta then continues downward as the abdominal aorta (or abdominal portion of the aorta) diaphragm to the aortic bifurcation. Aortic dissection and aortic aneurysm. An aortic dissection is a serious condition in which the inner layer of the aorta, the large blood vessel branching off the heart, tears. Blood surges through the tear, causing the inner and middle layers of the aorta to separate (dissect).  Ruptured aneurysms require emergency surgery to stop the bleeding. The aorta has many layers. Aortic dissection is a tear that develops in the inner layer of the aorta, causing blood to flow between the layers. The layers then separate, interrupting the blood flow and possibly causing the arterial wall to burst. 
http://biology.about.com/od/anatomy/a/aa041207a.htm http://www.healthline.com/human-body-maps/aortic-arch http://www.webmd.com/heart/picture-of-the-aorta http://www.medicinenet.com/script/main/art.asp?articlekey=2295 https://en.wikipedia.org/wiki/Aortic_dissection http://www.webmd.com/heart-disease/tc/aortic-aneurysm-overview https://en.wikipedia.org/wiki/Aorta http://www.mayoclinic.org/diseases-conditions/aortic-dissection/basics/definition/CON-20032930 http://my.clevelandclinic.org/services/heart/heart-blood-vessels/aorta
what is the aorta