الفهرس 
Introduction
The Role Of Pre-Operative AssessmentOnly 14 pages are availabe for public view
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Abstract
The aorta is the largest artery in the body, rising from the heart’s major pumping chamber, the left ventricle. Oxygen-rich blood enters the aorta with each contraction of the left ventricle and travels throughout the body through the smaller arteries branching from it.
The walls of the aorta are made up of three different layers of tissue: a thin inner layer (intima); a thick, elastic middle layer (media); and a thin outer layer (adventitia). The structure of these layers is important to the proper functioning of the aorta. As the heart contracts, forcing blood through the open aortic valve into the aorta, the walls of this artery must be flexible enough to absorb the force as blood surges into it.
The aorta is said to be an elastic blood vessel. Connective fibers within the aortic wall allow it to stretch as it experiences pressure, returning to its relaxed state as the force subsides. In the normal aorta these elastic fibers are present throughout and are especially dense in the wall of the ascending aorta, which experiences the greatest force with each heartbeat. (Feneis, 1994)
(2) Structure Of The Aorta & Its Branches:
1- Aortic root:
The root is the beginning of the aorta. Starting from the aortic valve (annulus) and becoming slightly wider in diameter (sinuses of Valsalva), it gives rise to two coronary arteries and ends at the beginning of the ascending aorta (sinotubular junction). The two coronary arteries are responsible for carrying oxygen-rich blood to the heart muscle itself.
2- Ascending aorta:
This segment extends upward from the aortic root to the point where the innominate artery branches off the aorta, and the aorta begins to form an arch. It is within the heart sack (pericardium) by itself and no arteries branch from it. There is little support from surrounding tissue and it must face the entire cardiac output volume (minus the coronary arteries), making the ascending segment the most vulnerable part of the aorta.