Heart valve 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. The pulmonary valve has left, right, and anterior cusps. The aortic valve has left, right, and posterior cusps. The
Crisscross heart Crisscross heart Crisscross heart is a type of congenital heart defect where the right atrium is closely associated with the left ventricle in space, and the left atrium is closely associated with the right ventricle. Although it is classified as a defect, the criss-cross is more of a spatial anomaly than a functional one, and it is possible for the heart to have relatively normal functioning. The ventricles are rotated either clockwise or counterclockwise resulting in the twisting of their connection. The actual blood flow stream through the ventricles is not interrupted. In an anatomically correct heart the right atrium