<P> The mitral valve and the aortic valve are in the left heart; the tricuspid valve and the pulmonary valve are in the right heart . </P> <P> There are also the coronary sinus and the inferior vena cava valves . </P> <P> The heart valves and the chambers are lined with endocardium . Heart valves separate the atria from the ventricles, or the ventricles from a blood vessel . Heart valves are situated around the fibrous rings of the cardiac skeleton . The valves incorporate leaflets or cusps, which are pushed open to allow blood flow and which then close together to seal and prevent backflow . The mitral valve has two cusps, whereas the others have three . There are nodules at the tips of the cusps that make the seal tighter . </P> <P> The pulmonary valve has left, right, and anterior cusps . The aortic valve has left, right, and posterior cusps . The tricuspid valve has anterior, posterior, and septal cusps; and the mitral valve has just anterior and posterior cusps . </P>

The cusps of the valves of the heart are covered by
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