( air, and to hold). The term aorta was used by the ancients, who supposed that only air was contained in it. The name of the great artery proceeding from the left ventricle of the heart, of which all other arteries, except the pulmonary, are the branches called also crassa arteria; magna arteria. From the heart it extends itself, by various branches, to the most distant parts of the body. Each of the.divisions and subdivisions of the aorta receives a different name, e. gr. the aorta gives rise to the carotid and the subclavian arteries, the branches of these again receive other names. These branches are in pairs, except the coeliaca, the two mesentericae, some of the oesophageae, the bronchialis, and sometimes the sacrae.
The beginning of the aorta is furnished with semilunar valves, as the pulmonary artery; and the same triangular bodies close up the little space left by the valves. It is larger in women than in men. It is called the ascending aorta from the heart, so far as it goes upwards; and descending, from its curvature downwards, to the os sacrum, where it terminates in the iliacs. The descending aorta is divided into the superior, which reaches from the curvature to the diaphragm; and the inferior, which extends thence to the bifurcation, where the iliacs begin.
The aorta goes from the basis of the heart, nearly opposite to the fourth vertebra of the back, and ascends obliquely, with respect to the body, from the left to the right side, and from before backwards; then bends obliquely from the right to the left side, and from before backwards, reaching as high as the second vertebra of the back, from whence it runs down again in the same direction, forming an oblique arch. From this it descends in a direct course along the anterior part of the vertebrae, all the way to the os sacrum, lying a little towards the left hand, and there terminates in its two subordinate branches in the iliacae.
The aorta ascendens is principally distributed to the thorax, head, and upper extremities: the superior portion of the aorta descendens furnishes the rest of the thorax: the inferior portion furnishes the abdomen and the lower extremities.
The aorta is subject to many disorders, as inflammation, ulcers, polypuses, aneurisms, ossification, etc.