Arteries of the trunk. Thoracic aorta

The thoracic aorta (thoracic aorta), pars thoracica aortae (aorta thoracica), is located in the posterior mediastinum, directly on the vertebral column.

The upper parts of the thoracic aorta are on the left side of the spinal column, then the aorta blends slightly to the right and passes into the abdominal cavity, located somewhat to the left of the median line. To the right of the thoracic part of the aorta adjoin the thoracic duct, ductus thoracicus, and unpaired vein, v. Azygos, on the left - a semi-unpaired vein, v. Hemiazygos, in front - the left bronchus. The upper third of the esophagus is located to the right of the aorta, the middle one is in front, and the lower one is to the left.

From the thoracic aorta there are two types of branches: the parietal and the inward branches.

Parietal branches

1. Upper diaphragmatic arteries, aa. Phrenicae superiores, only two, extend from the anterior wall of the lower part of the aorta and are directed to the upper surface of the lumbar part of the diaphragm, anastomizing in its thickness with the branches of the lower diaphragmatic arteries from the abdominal part of the aorta.

2. Posterior intercostal arteries (III-XI), aa. Intercostales posteriores, are rather powerful vessels, only 10 pairs, move away from the posterior surface of the thoracic part of the aorta throughout its entire length. Nine of them lie in the intercostal spaces, from the third to the eleventh inclusive, and the lowest ones go under the XII ribs and are called the subcostal arteries, aa. Subcostales.

The right posterior intercostal arteries are somewhat longer than the left ones, since the thoracic part of the aorta is located on the left surface of the spinal column.

Each posterior intercostal artery in its turn gives the dorsal branch, r. Dorsalis, and itself goes a little upward and goes along the inner surface of the external intercostal muscle; Is covered only by the thoracic fascia and parietal pleura. Passes in the furrow of the overlying rib.

In the area of ​​the corners of the ribs from the posterior intercostal artery a rather powerful collateral branch departs, r. Collateralis. It is directed downwards and anteriorly, along the upper edge of the underlying rib, passing between the outer and inner intercostal muscles and supplying blood to their lower parts.

Starting from the corners of the ribs, a. Intercostalis posterior and r. Collateralis go along the intercostal space between the outer and inner intercostal muscles and anastomose with rr. Intercostales anteriores a. Thoracicae internae (from a. Subclavia), and the first intercostal artery anastomoses with a. Intercostalis suprema. The terminal branches of the intercostal arteries, from the 7th to the 12th, cross the edge of the costal arch and come out between the layers of the broad abdominal muscles, blood supplying them and the rectus abdominal muscles. They anastomose with the branches of the upper and lower epigastric arteries, aa. Epigastricae superior et inferior.

Posterior intercostal artery gives lateral cutaneous branch, r. Cutaneus lateralis, which perforates the intercostal or broad abdominal muscles and exits into the subcutaneous layer, as well as the branches of the breast, rr. Mammarii, which depart from the 4th, 5th and 6th intercostal arteries.

From the initial site of the posterior intercostal artery the dorsal branch departs, r. Dorsalis, which is directed under the neck of the rib, between its ligaments, to the posterior (dorsal) surface of the trunk; A spinal cord, r, is inserted through the intervertebral foramen to the spinal cord. Spinalis, which in the vertebral canal anastomoses with the vessels lying above and below the vessels of the same name and with the same branch of the opposite side, forming an arterial ring around the spinal cord. It also supplies the membranes of the spinal cord and vertebrae.

The terminal trunks of the posterior branches go further posteriorly, giving off the muscle branches. Then each of the end trunks is divided into two branches - medial and lateral. Medial cutaneous branch, r. Cutaneus medialis, blood supply to the skin in the region of spinous processes and on its way gives a series of small branches to the longest and semi-oval muscles. Lateral cutaneous branch, r. Cutaneus lateralis, blood supply to the skin of the lateral parts of the back, and also gives twigs to the ilio-rib muscle.

Internal branches

1. Bronchial branches, rr. Bronchiales, only two, less often 3 - 4, depart from the anterior wall of the initial part of the thoracic aorta, enter the gates of the lungs and branch out together with the bronchi.
The terminal branches of the bronchial branches are directed to the bronchopulmonary lymph nodes, pericardium, pleura and esophagus.

2. Esophageal branches, rr. Esophageales, only 3 to 6, are sent to the esophagus site where it is in contact with the aorta, and branch out here into ascending and descending branches. In the lower parts, the esophageal branches are anastomosed with the left gastric artery, a. Gastrica sinistra, and in the upper - with the lower thyroid artery, a. Thyroidea inferior.

3. Mediastinal branches, rr. Mediastinales, - numerous small branches that start from the anterior and lateral walls of the aorta; Blood supply connective tissue and lymph nodes of the mediastinum.

4. Pericardial branches, rr. Pericardiaci, - small vessels, the number of which varies, are sent to the posterior surface of the pericardium.