The thoracic aorta is the proximal, 20 cm long section of the descending aorta. Anatomically, the thoracic aorta is positioned to the left of the vertebral column. It starts between the T4 and T5 vertebrae and enters the diaphragm through the aortic hiatus, an opening in the diaphragm. Along its path, the thoracic aorta branches into several visceral and parietal branches. The visceral branches supply blood mainly to the viscera. It gives off four important arteries. The pericardial artery supplies blood to the pericardium. The bronchial artery supplies the lungs and bronchi, and the esophageal artery carries blood to the esophagus. The mediastinal artery supplies to the structures in the mediastinum and lymph nodes. The parietal branch includes three significant arteries. The nine pairs of intercostal arteries supply blood to the ribs, muscles, and skin of the chest wall. The paired subcostal and superior phrenic arteries supply blood to the lower part of the chest wall and diaphragm.