Heart valves arise from the endocardial cushions and the surrounding myocardium. The atrioventricular (AV) valves, including the mitral and tricuspid valves, form from the AV endocardial cushions. The semilunar valves, such as the aortic and pulmonary valves, develop from the conotruncal endocardial cushions. Proper valve development ensures unidirectional blood flow through the heart.
