Human Anatomy, Part 2 - K. A. Dyubenko, A. K. Kolomiytsev, Yu. B. Chaikovsky 2008

Special Part
Cardiovascular system, systema cardiovasculare - Special Part
Blood vessels of the systemic circulation - Arterial system - Aorta

The aorta is the main arterial trunk of the systemic Circulation (Figs. 16, 21). It is traditionally divided into three parts: the ascending aorta (aorta ascendens), the aortic arch (arcus aortae), and the descending aorta (aorta descendens).

The ascending aorta (aorta ascendens) is approximately 6 cm long (Fig. 20). It originates in the left ventricle from the conus arteriosus and extends from the level of the semilunar valve to the Water/144.html">Origin of the brachiocephalic trunk (truncus brachiocephalicus). Just above the semilunar valve lies an aortic dilatation known as the aortic bulb (bulbus aortae). On the internal surface of this dilatation, there are three outpouchings—the aortic sinuses (sinus aortae)—located between the aortic wall and the cusps of its valve. The coronary Arteries of the Heart arise in the region of these sinuses.

The aortic arch (arcus aortae) (Fig. 21) lies posterior to the manubrium of the Sternum in the superior Mediastinum, arches over the left main bronchus and the bifurcation of the pulmonary trunk, and continues as the descending aorta at the level of the fourth thoracic vertebra. Three vessels branch off the superior surface of the aortic arch: the brachiocephalic trunk, the left common carotid artery, and the left Subclavian Artery.

From the Inferior surface of the aortic arch, small, slender arteries branch off to supply the Bronchi and the Thymus gland. The typical branching pattern of the aortic arch is observed in 77% of cases, while the remaining 23% represent anatomical variants (Lippert).

The descending aorta (aorta descendens) is situated in the posterior mediastinum and is about 17 cm long (Fig. 21 A). Initially located to the left of THE Vertebral Column, it gradually shifts slightly to the right and enters the Abdominal cavity through the aortic hiatus (hiatus aorticus) of the Diaphragm, becoming the Abdominal Aorta (aorta abdominalis). The segment of the descending aorta extending to the aortic hiatus is called the Thoracic Aorta (aorta thoracica). At the level of the fourth lumbar vertebra, the abdominal aorta bifurcates (bifurcatio aortae) into the two common iliac arteries, while continuing directly as the median sacral artery (a. sacralis mediana).

* The most common anatomical variations in the branching of the aortic arch include: 1. Bilateral brachiocephalic trunks. 2. A common trunk shared by the carotid arteries and the left subclavian artery. 3. A common trunk for the two carotid arteries, with separate origins for the subclavian arteries. 4. Absence of the brachiocephalic trunk, with the right and left subclavian arteries arising separately (V. V. Kupriyanov, N. V. Voskresensky, 1970).