Aorta

The aorta is the largest artery in the human body, originating at the aortic valve and extending to its bifurcation in the lower abdomen. It serves as the principal conduit for oxygenated blood from the left ventricle to the systemic circulation. The aorta is divided into five main segments: the aortic root (from the aortic valve annulus to the sinotubular junction), the ascending thoracic aorta (from the sinotubular junction to the brachiocephalic trunk), the aortic arch (from the brachiocephalic trunk to the left subclavian artery), the descending thoracic aorta (from the left subclavian artery to the diaphragm), and the abdominal aorta (from the diaphragm to the aortic bifurcation).

The aortic wall is composed of three layers: the intima (a thin endothelial layer), the media (a thick layer of smooth muscle cells, elastic fibers, and collagen providing strength and distensibility), and the adventitia (an outer layer of connective tissue, fibroblasts, nerves, and vasa vasorum).