The largest blood vessel in the human body is the aorta. Rising up from the left ventricle of the heart, the aorta curves down and passes through the chest cavity and into the abdomen.
Arteries, which carry blood under direct pressure from the heart, tend to be thicker and more elastic than veins, which carry blood back to the heart. The aorta branches, supplying blood to the head, neck and arms, before descending into the chest where it branches further to provide blood to the ribs and chest structures. Near the bottom of the abdomen, it splits into the iliac arteries, which provide blood to the legs. The largest veins in the body are the superior and inferior vena cava, which empty deoxygenated blood directly into the right atrium of the heart.