the semilunar valves are located at the base in the aorta.
the semilunar valves are located at the base in the aorta.
where are the semilunar valves located in the aorta?
base
the aortic and pulmonary valves are located at the base of the aorta and the pulmonary trunk respectively. these are also called the "semilunar valves". these two arteries receive blood from the ventricles and their semilunar valves permit blood to be forced into the arteries, and prevent backflow from the arteries into the ventricles. these valves do not have chordae tendineae, and are more similar to the valves in veins than they are to the atrioventricular valves. the closure of the semilunar valves causes the second heart sound.
heart valve
the semilunar valves (the pulmonary and aortic valves) are formed from four thickenings at the cardiac end of the truncus arteriosus. these thickenings are called endocardial cushions. the truncus arteriosus is originally a single outflow tract from the embryonic heart that will later split to become the ascending aorta and pulmonary trunk. before it has split, four thickenings occur. there are anterior, posterior, and two lateral thickenings. a septum begins to form between what will later become the ascending aorta and pulmonary tract. as the septum forms, the two lateral thickenings are split, so that the ascending aorta and pulmonary trunk have three thickenings each (an anterior or posterior, and half of each of the lateral thickenings). the thickenings are the origins of the three cusps of the semilunar valves. the valves are visible as unique structures by the ninth week. as they mature, they rotate slightly as the outward vessels spiral, and move slightly closer to the heart.
heart valve