The blood that flows through the pulmonary arteries connecting the right side of the heart with the lungs has not yet picked up oxygen, so this blood has a dark bluish color. Blood flow is due to contraction of the heart muscle assisted by artery muscle contraction. The largest artery is the aorta, which stems directly from the heart. Two small branches of the aorta, the coronary arteries, supply the blood that nourishes the heart muscle itself. The right and left carotid arteries carry blood to the two sides of the neck and head.
Blood flows to the shoulders and arms through the right and left subclavian arteries.
In the abdominal region, the aorta divides into two large branches, the left and right iliac, that supply blood to the pelvic region. The iliac arteries then continue into the legs, where they are referred to as the femoral arteries. The blood passes from the arteries into the very small capillaries. The blood then goes from the capillaries to the veins and returns to the heart. The heart pumps this blood through the pulmonary artery to the lungs, where it receives new oxygen.