Human Anatomy - Kotsan I. Y. 2009

Vessels of the lesser (pulmonary) circulation
Branches of the thoracic aorta
Parietal branches of the thoracic aorta

The Branches of the Thoracic Aorta are conventionally divided into parietal and visceral branches. The parietal branches supply the walls of the thoracic cavity, while the visceral branches supply the Organs located primarily in the posterior Mediastinum.

1. The superior phrenic Arteries (aa. phrenicae superiores) are paired arteries that arise from the anterior surface of the aorta directly above the Diaphragm, running toward the upper surface of the lumbar part of the diaphragm and the adjacent Pleura.

2. The posterior intercostal arteries (aa. intercostales posteriores), numbering ten pairs, branch off from the posterolateral surfaces of the thoracic aorta. Nine of these lie in the intercostal spaces, from the third to the eleventh inclusive, while the last (tenth) pair runs beneath the twelfth Ribs and is termed the subcostal arteries (aa. subcostales), each giving off dorsal and spinal branches (r. dorsahs et r. spinalis). The posterior intercostal arteries supply the intercostal Muscles, ribs, and Skin of the chest. The lower arteries also supply the Muscles of the anterior abdominal wall.

The right intercostal arteries are slightly longer than the left, as the aorta in this region is positioned asymmetrically on the left side of THE Vertebral Column.

Each posterior intercostal artery gives off the following branches: 1) the dorsal branch (r. dossalis), which runs to the skin and muscles of the back and gives off a spinal branch (r. spinalis) that passes through the intervertebral foramen to the Spinal Cord and its membranes; 2) the lateral and medial cutaneous branches (r. cutaneus lateralis et r. cutaneus medialis), which extend to the skin of the chest and abdomen. From the lateral cutaneous branches of the IV–VI posterior intercostal arteries, lateral mammary branches (rr. mammarii laterales) arise to vascularize the mammary gland.