A heart valve normally allows blood to flow in only one direction through the heart. The four valves commonly represented in a mammalian heart determine the pathway of blood flow through the heart, a heart valve opens or closes incumbent on differential blood pressure on each side. The four main valves in the heart are, The two atrioventricular valves, the valve, and the tricuspid valve, which are between the upper chambers and the lower chambers. The two semilunar valves, the valve and the pulmonary valve, which are in the arteries leaving the heart. The mitral valve and the valve are in the left heart, the tricuspid valve. There are also the coronary sinus and the inferior vena cava valves, 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, 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 tricuspid valve has anterior, posterior, and septal cusps, and the mitral valve has just anterior and posterior cusps. These are the mitral and tricuspid valves, which are situated between the atria and the ventricles and prevent backflow from the ventricles into the atria during systole and they are anchored to the walls of the ventricles by chordae tendineae, which prevent the valves from inverting. The chordae tendineae are attached to muscles that cause tension to better hold the valve. Together, the muscles and the chordae tendineae are known as the subvalvular apparatus. The function of the apparatus is to keep the valves from prolapsing into the atria when they close. The subvalvular apparatus has no effect on the opening and closure of the valves, however, the peculiar insertion of chords on the leaflet free margin, however, provides systolic stress sharing between chords according to their different thickness. The closure of the AV valves is heard as lub, the first heart sound, the closure of the SL valves is heard as dub, the second heart sound. The mitral valve is called the bicuspid valve because it contains two leaflets or cusps. The mitral valve gets its name from the resemblance to a bishops mitre and it is on the left side of the heart and allows the blood to flow from the left atrium into the left ventricle
This is further explanation of the echocardiogram above. MV: Mitral valve, TV: Tricuspid valve, AV: Aortic valve, Septum: Interventricular septum. Continuous lines demarcate septum and free wall seen in echocardiogram, dotted line is a suggestion of where the free wall of the right ventricle should be. The red line represents where the upper left loop in the echocardiogram transects the 3D-loop, the blue line represents the lower loop.
Illustration of the valves of the heart when the ventricles are contracting.
Structure of the heart valves
Wiggers diagram, showing various events during a cardiac cycle, with closures and openings of the aortic and mitral marked in the pressure curves.