The semilunar Valves are pocketlike structures attached at the point at which the pulmonary artery and the aorta leave the ventricles. A Semilunar Valve is the heart valve at the base of the aorta and the pulmonary artery, and consisting of cusps or flaps that prevent the backflow of the blood during systole. Semilunar Valves are paired valves of the heart at the bases of the aorta and the pulmonary artery.
