Aorta. Parts of the aorta

The aorta (aorta) is the largest vessel in the human body. It gives rise to all the arteries of the systemic circulation. It divides into the ascending part, the arch, and the descending part.

The aorta arises from the left ventricle (ventriculus dexter). It is located to the left of the middle line of the body and arises from the left ventricle at the level of the third intercostal space.

The ascending aorta (pars ascendens aortae) rises superiorly on the inferior side and a bit to the right from the pulmonary trunk. At the level of the joint between the second costal cartilage and the sternum, it passes into the arch of the aorta.

At the beginning of the aorta, there is the bulb of the aorta (bulbus aortae). It is covered by the pericardium and is located in the middle mediastinum.

Inside the bulb of the aorta (bulbus aortae), there are three aortic sinuses (sinus aortae),

which are located between the internal surface of the aorta and the corresponding semilunar cusp of the aortic valve (valva aortae).

Two arteries arise from the ascending aorta. These arteries branch off from the beginning of the ascending aorta in the bulb area and supply the myocardium with blood. They are:

The right coronary artery (a. coronaria dextra)

The left coronary artery (a. coronaria sinistra)

The arch of the aorta (arcus aortae), which is the continuation of the ascending aorta. It is turned to the left and posteriorly from the posterior surface of the second costal cartilage to the left side of the body of the fourth thoracic vertebra. The arch is thrown over the beginning of the left main bronchus.

Three major arteries arise from it. We list them from the proximal section to the distal:

The brachiocephalic trunk (truncus brachiocephalicus)

The left common carotid artery (a. carotis communis sinistra)

The left subclavian artery (a. subclavia sinistra)

These arteries supply the upper limbs and organs of the head and neck with blood.

The descending aorta (pars descendens aortae) is the longest segment of the aorta, which divides into two parts: the thoracic and abdominal aorta. It is located between the fourth thoracic spine and the fourth lumbar spine, at the level of which it divides into the right and left common iliac arteries (aortic bifurcation):

The left common iliac artery (a. iliaca communis sinistra)

The right common iliac artery (a. iliaca communis dextra)

These arteries supply the lower limbs and pelvic organs with blood.

The thoracic aorta (pars thoracica aortae) arises from the arch of the aorta and, passing through the diaphragm, continues into the abdominal aorta. It is located in the posterior mediastinum and to the left of the median line.

First it lies anteriorly and slightly to the left of the oesophagus, then at the level of the thoracic vertebrae 8 and 9 it circumflexes the oesophagus on the left side and goes to its posterior surface. The azygos vein and thoracic duct are located to the right of the thoracic aorta, and the parietal pleura is located to the left. The aorta passes into the abdominal cavity through the aortic hiatus (hiatus aorticus) of the diaphragm.

The thoracic aorta has two groups of branches:

The parietal branches, which supply the walls of the thoracic cavity, the diaphragm, and most of the anterior abdominal wall with blood.

The visceral branches, which supply the thoracic organs with blood.

The parietal branches include:

The superior phrenic artery (a. phrenica superior), which is paired and arises from the aorta above the diaphragm, goes to the lumbar part of the diaphragm of its side and supplies its posterior part with blood.

There are 10 pairs (or 11, according to some sources) of posterior intercostal arteries, which pass in the corresponding intercostal spaces and supply the following structures with blood: muscles and skin of the chest and abdomen, thoracic vertebrae and ribs, the spinal cord and its membranes, and the diaphragm.

Posterior intercostal arteries (aa. intercostales posteriores)

It is important to note that the first and second posterior intercostal arteries arise from the superior intercostal artery (branches of the costocervical trunk). And the 3rd-10th (11th) arteries arise directly from the thoracic aorta.

In their course, the posterior intercostal arteries give off several branches:

The collateral branch (r. collateralis) arises from the posterior intercostal artery in the area of the angle of the rib.

The dorsal branch (r. dorsalis) arises from the posterior intercostal artery at the level of the head of the rib. It goes in the posterior direction to the muscles and skin of the back area, while being accompanied by the dorsal branch of the spinal nerve. Along its course, the dorsal branch of the posterior intercostal artery also gives off several branches of its own:

The medial cutaneous branches (r. cutaneus medialis), which supply the skin of the lateral walls of the thorax with blood

The lateral cutaneous branches (r. cutaneus lateralis), which supply the skin of the lateral walls of the thorax with blood

Lateral cutaneous branches (rr. cutaneus lateralis)

The spinal branch (r. spinalis) passes through the adjacent intervertebral foramen to the spinal cord, membranes, and roots of spinal nerves.

The branches four to six give off the branches of the mammary gland (rr. mammarii laterales), which supply it with blood.

And the last parietal branches of the thoracic aorta are the subcostal arteries (aa. subcostales). In fact, they are similar to the posterior intercostal arteries, only they are located under the 12th pair of ribs.

The visceral branches of the thoracic aorta include:

The bronchial branches (rr. bronchiales), which arise from the aorta at the level of the thoracic vertebrae 4 and 5 and the left main bronchus. In this case, one right and two left bronchial branches are usually distinguished. They insert into the hila of the lungs and supply the trachea, bronchial tree, and esophagus with blood

The oesophageal branches (rr. oesophagei) arise from the aorta at the level of the thoracic vertebrae 4 to 8.

They pass to the walls of the thoracic part of the oesophagus. The inferior oesophageal branches anastomose with the oesophageal branches of the left gastric artery (rr. oesophagei a. gastrica sinistra).

Oesophageal branches of the left gastric artery (rr. oesophagei a. gastrica sinistra)

The pericardial branches (rr. pericardiaci) arise from the aorta behind the pericardium and pass to the posterior part of the pericardium. They supply the pericardium, lymph nodes and the connective tissue of the posterior mediastinum.

The mediastinal branches (rr. mediastinales) arise from the thoracic aorta in the posterior mediastinum. They supply the fatty tissue and lymph nodes of the posterior mediastinum.

Anastomoses:

The bronchial branches (rr. bronchiales) anastomose with the branches of the pulmonary artery (a. pulmonalis).

The spinal branches (r. spinalis) anastomose in the spinal canal with the branches of the same name on the opposite side, and with the spinal branches of the vertebral (a. vertebralis), ascending cervical (a. cervicalis ascendens) and lumbar arteries (a. lumbales).

The posterior intercostal arteries 1 to 8 anastomose with the anterior intercostal branches (rr. intercostales anteriores) of the internal thoracic artery (a. thoracica interna)

The posterior intercostal arteries 9 to 11 (aa. intercostales posteriores) anastomose with the branches of the superior epigastric artery (a. epigastrica superior) of the internal thoracic artery (a. thoracica interna).

The abdominal aorta (pars abdominalis aortae) is the continuation of the thoracic aorta after it passes through the diaphragm. It lies retroperitoneally on the anterior surface of the bodies of the lumbar vertebrae and to the left of the median line.

To the right of the aorta, there is the inferior vena cava. Anteriorly to the aorta, there is the pancreas, the lower horizontal part of the duodenum, and the root of the mesentery. Inferiorly, the abdominal aorta shifts gradually in the medial direction. At the level of the fourth lumbar vertebra, there is an aortic bifurcation (bifurcatio aortae).