<P> The aortic arch ends and the descending aorta begins at the level of the intervertebral disc between the fourth and fifth thoracic vertebrae . </P> <P> The thoracic descending aorta gives rise to the intercostal and subcostal arteries, as well as to the superior and inferior left bronchial arteries and variable branches to the esophagus, mediastinum, and pericardium . Its lowest pair of branches are the superior phrenic arteries, which supply the diaphragm, and the subcostal arteries for the twelfth rib . </P> <P> The abdominal aorta begins at the aortic hiatus of the diaphragm at the level of the twelfth thoracic vertebra . It gives rise to lumbar and musculophrenic arteries, renal and middle suprarenal arteries, and visceral arteries (the celiac trunk, the superior mesenteric artery and the inferior mesenteric artery). It ends in a bifurcation into the left and right common iliac arteries . At the point of the bifurcation, there also springs a smaller branch, the median sacral artery . </P> <P> The ascending aorta develops from the outflow tract which initially starts as a single tube connecting the heart with the aortic arches (which will form the great arteries) in early development, but then is separated into the aorta and the pulmonary trunk . </P>

An important artery that supplies blood to the brain