Anatomy of the Vessels and Nerves of the Trunk (Angioneurology) - Chornokulskyi S. T. 2011

Vessels of the Systemic Circulation. Trunk Arteries
Thoracic Aorta

The thoracic part of the aorta (pars thoracica aortae) or the thoracic aorta (aorta thoracica)

This is the segment of the descending aorta between Th_IV and Th_XII, located predominantly to the left of THE Vertebral Column.

In its upper third, the thoracic aorta lies to the left and anterior to the Esophagus; in the middle third, it is situated to the left and at the same level as the esophagus; in the lower third, it crosses posterior to the esophagus. As an organ of the posterior Mediastinum, the thoracic aorta is bordered on the right by the Thoracic duct and the azygos vein, on the left by the hemiazygos vein, and is crossed anteriorly in its upper third by the left main bronchus.

Its branches are divided into visceral and parietal groups:

I. Visceral branches

1. Bronchial branches (rr. bronchiales) (2–3) run toward the tracheal bifurcation and ramify within the bronchial tree, anastomosing with Branches of the pulmonary artery at the capillary level.

2. Esophageal branches (rr. oesophageales) (1–5) supply the wall of the esophagus, anastomosing in its lower third with the left gastric artery and in its upper third with the inferior thyroid artery.

3. Pericardial branches (rr. pericardiaci) pass to the posterior surface of the Pericardium.

4. Mediastinal branches (rr. mediastinales) supply the Lymph Nodes AND Connective Tissue of the posterior mediastinum.

II. Parietal branches

5. Superior phrenic Arteries (aa. phrenicae superiores) are paired (right and left) and supply the lumbar part of the Diaphragm and the adjacent Pleura.

6. Posterior intercostal arteries (aa. intercostales posteriores) comprise ten vessels on each side, located in the III–XI intercostal spaces. The tenth arteries lie beneath the XII Ribs and are therefore termed subcostal arteries (aa. subcostales).

Each posterior intercostal artery runs in the costal groove as part of the neurovascular bundle [from superior to inferior: vein, artery, nerve (VAN)] between the external and internal intercostal Muscles.

Branches of the posterior intercostal artery

1. Dorsal branch (r. dorsalis) supplies the Skin and Muscles of the back. It gives off a spinal branch (r. spinalis) that passes through the intervertebral foramen to supply the Spinal Cord and its Meninges.

2. Collateral branch (r. collateralis) runs forward and downward within the intercostal space toward the upper border of the rib below.

The lateral cutaneous branch (r. cutaneus lateralis) supplies the skin of the chest and abdomen. The IV–VI lateral cutaneous branches give off lateral mammary branches (rr. mammarii laterales) to the breast. The last six posterior intercostal arteries course toward the anterior abdominal wall, supplying its muscles and skin. The lower three of these anastomose with the aa. epigastricae superiores et inferiores. The terminal segments of the upper posterior intercostal arteries anastomose with the anterior intercostal branches (from the a. thoracica interna), forming intersystemic interarterial anastomoses.

The posterior intercostal arteries also supply the parietal pleura and Peritoneum, all intercostal muscles, and the ribs.