Aorta

The aortais the largest unpaired arterial vessel of the systemic circulation. The aorta is divided into three sections: the ascending aorta, the aortic arch, and the descending aorta, which in turn is divided into the thoracic and abdominal sections.

The ascending aorta (pars ascendens aortae) emerges from the left ventricle behind the left edge of the sternum at the level of the third intercostal space. In the initial section it has an expansion - the aortic bulb (bulbus aortae, 25-30 mm in diameter). At the location of the aortic valve, on the inner side of the aorta there are three sinuses (sinus aortae). Each of them is located between the corresponding semilunar valve and the wall of the aorta. The right and left coronary arteries branch off from the beginning of the ascending aorta. The ascending aorta lies behind and partly to the right of the pulmonary trunk, rises upward and at the level of the junction of the cartilage of the second right rib with the sternum passes into the aortic arch (here its diameter is 21-22 mm).

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Branches of the aorta

Branches of the ascending aorta

1. Coronary arteries

Branches of the aortic arch

1. Brachiocephalic trunk
2. Left common carotid artery
3. Left subclavian artery

Branches of the descending aorta

1. Thoracic aorta
   • Bronchial branches
   • Mediastinal branches
   • Esophageal branches
   • Superior phrenic arteries
   • Pericardial branches
   • Posterior intercostal arteries
2. Abdominal aorta
   • Unpaired branches
     • Celiac trunk
     • Superior mesenteric
     • Inferior mesenteric
     • Median sacral
   • Paired branches
     • Inferior phrenic arteries
     • Middle adrenal artery artery
     • Renal arteries
     • Testicular (ovarian) arteries artery
     • Lumbar arteries
     • Common iliac arteries artery

The aortic arch (arcus aortae) turns left and back from the posterior surface of the cartilage of the 2nd rib to the left side of the body of the 4th thoracic vertebra, where it passes into the descending aorta. At this point there is a slight narrowing - the isthmus of the aorta (isthmus aortae). The edges of the corresponding pleural sacs approach the anterior semicircle of the aorta on its right and left sides. The left brachiocephalic vein is adjacent in front to the convex side of the aortic arch and to the initial sections of the large vessels branching off from it (the brachiocephalic trunk, the left common carotid and subclavian arteries), and the right pulmonary artery begins under the aortic arch , with the bifurcation of the pulmonary trunk located below and slightly to the left . The bifurcation of the trachea is located behind the aortic arch . Between the concave semicircle of the aortic arch and the pulmonary trunk or the beginning of the left pulmonary artery there is an arterial ligament (lig. arteriosum). At this point, thin arteries branch off from the aortic arch to the trachea and bronchi. Three large arteries begin from the convex semicircle of the aortic arch: the brachiocephalic trunk, the left common carotid, and the left subclavian.

The descending aorta (pars descendes aortae) is the longest section of the aorta, extending from the level of the fourth thoracic vertebra to the fourth lumbar vertebra, where it divides into the right and left iliac arteries; this place is called the bifurcation of the aorta (bifurcatio aortae). The descending aorta is in turn divided into the thoracic and abdominal parts.

The thoracic aorta (pars thoracica aortae) is located in the thoracic cavity, in the posterior mediastinum. Its upper section is located in front and to the left of the esophagus. Then, at the level of the VIII-IX thoracic vertebrae, the aorta bends around the esophagus on the left and goes to its posterior surface. To the right of the thoracic aorta are the azygos vein and the thoracic duct, to the left of it is adjacent to the parietal pleura, at the place where it passes into the posterior section of the left mediastinal pleura. In the thoracic cavity, the thoracic aorta gives off paired parietal branches - the posterior intercostal arteries, as well as visceral branches to the organs of the posterior mediastinum.

The abdominal aorta (pars abdominalis aortae), being a continuation of the thoracic aorta, begins at the level of the 12th thoracic vertebra, passes through the aortic opening of the diaphragm and continues to the level of the middle of the body of the fourth lumbar vertebra. The abdominal aorta is located on the anterior surface of the bodies of the lumbar vertebrae, to the left of the midline, lies retroperitoneally. To the right of the abdominal aorta is the inferior vena cava, in front - the pancreas, the horizontal (lower) part of the duodenum and the root of the mesentery of the small intestine. The abdominal aortic (vegetative) plexus, nodes of the celiac, aortorenal and intermesenteric plexuses are located on the aorta. The abdominal aorta gives off paired parietal branches to the diaphragm and the walls of the abdominal cavity, and the aorta itself directly continues into the thin median sacral artery. The visceral branches of the abdominal aorta are the celiac trunk, the superior and inferior mesenteric arteries (unpaired branches) and the paired ones - the renal, middle adrenal, testicular (ovarian) arteries.