Aorta

(a-ort'-ah). The great arterial ve el arising from the left ventricle and ending with its bifurcation into the two common iliacs at the fourth lumbar vertebra. The arch, that extending from the heart to the third thoracic vertebra, is divided into an ascending, a transverse, and a descending part. The thoracic portion extends to the diaphragm; the abdominal, to the bifurcation. The diseases of the aorta are acute aortitis, due to traumatism, thrombosis, etc.; and the chronic form, or atheroma of the aorta; fatty degeneration; stenosis; aneurysm. See Artery .