Aortic Valve

When the left ventricle of the heart contracts, the bicuspid valve closes, and the only way out is through a large artery called the "aorta." The branches of the aorta distribute blood to all parts of the body (See Arch of the Aorta). At the base of the aorta, there is an "aortic semilunar valve" that has three leaflets or cusps. It opens to allow blood to leave the left ventricle as it contracts. When the ventricular muscles relax, the valve closes to prevent blood from backing up into the ventricular chamber.