According to WebMD, the main artery in the body is the aorta. It is connected to the left ventricle of the heart. The aorta branches off into a web of numerous smaller arteries that exist all over the body.
WebMD explains that the aorta measures around a foot in length and an inch in diameter. There are four sections of the aorta: the ascending aorta, the aortic arch, the descending thoracic aorta and the abdominal aorta. The pulmonary arteries are unique among the numerous arteries in the human body because they transport blood lacking in oxygen to the lungs. The numerous arteries themselves have smaller branches called capillaries and arterioles.