The common iliac arteries branch off from the end of the abdominal aorta (the main blood vessel that exits the heart, bringing oxygen-rich blood to the rest of the body). The common iliac arteries provide the primary blood supply to the lower limbs. Atherosclerosis is when plaque (cholesterol containing fatty deposits) builds up and hardens the blood vessels, and if it progresses, can block blood flow causing heart attack or stroke. Risk factors for atherosclerosis include high blood pressure, poor cholesterol, diabetes, and smoking.