The ascending aorta, or aorta ascendens, along with its constituents, amounts to about five centimeters in length. It constitutes the initial division of the aorta, the largest artery in the body. It originates from the upper portion of the left ventricle of the heart at the aortic valve "on a level with the lower border of the third costal cartilage behind the left half of the sternum; it passes obliquely upward, forward, and to the right, in the direction of the heart's axis, as high as the upper border of the second right costal cartilage, describing a slight curve in its course, and being situated, about 6 cm. behind the posterior surface of the sternum." (Gray" 1) It then gives rise to the right and left coronary arteries, which supply the heart muscle. It then curves left continuing into the arch of the aorta. Originating from the aorta are the right brachiocephalic trunk, left common carotid, and left subclavian arteries. The coronary arteries, thus being, the only branches of the ascending aorta.
At the entrance of the ascending aorta are three minute aortic sinuses and the Aortic Semilunar Valve, a three-cusped valve located at the base of the ascending aorta behind the sternum at the level of the third intercostal space (Grine 273). The point at which the ascending aorta converges with the aortic arch is termed the bulb of the aorta, a swelling due to vessel increasement on the right wall. Lying superior to the ascending aorta is the trunk of the pulmonary artery and the auricular appendage of the right atrium. It is partitioned from the sternum by the serous pericardium, the right pleura, the anterior margin of the right lung, some loose areolar tissue, and the remains of the thymus. Posteriorly, it is propped upon the left atrium and right pulmonary artery. Lying adjacent on the right border is the superior vena cava and right atrium. Lying opposite on the left border is the pulmonary artery and pulmonary trunk (Gray" 1). The ascending...
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