The descending aorta is the portion of the aorta in a two-pass circulatory system from the arch of aorta to the point where it divides into the common iliac arteries[GO]. The descending aorta is part of the aorta, the largest artery in the body. The descending aorta is the part of the aorta beginning at the aortic arch that runs down through the chest and abdomen. The descending aorta is divided into two portions, the thoracic and abdominal, in correspondence with the two great cavities of the trunk in which it is situated. Within the abdomen, the descending aorta branches into the two common iliac arteries which serve the legs. [WP,unvetted]. [ http://en.wikipedia.org/wiki/Descending_aorta http://amigo.geneontology.org/amigo/term/GO:0035906 ]