Heart valve or cusps. The mitral valve gets its name from the resemblance to a bishop's mitre (a type of hat). It is on the left side of the heart and allows the blood to flow from the left atrium into the left ventricle. During diastole, a normally-functioning mitral valve opens as a result of increased pressure from the left atrium as it fills with blood (preloading). As atrial pressure increases above that of the left ventricle, the mitral valve opens. Opening facilitates the passive flow of blood into the left ventricle. Diastole ends with atrial contraction, which ejects the final 30%
Mitral valve the left ventricle. It has two leaflets (or 'cusps'), an anteromedial leaflet, and a posterolateral leaftlet. The opening of the mitral valve is surrounded by a fibrous ring known as the "mitral annulus". The anterior cusp covers approximately two-thirds of the valve (imagine a crescent moon within the circle, where the crescent represents the posterior cusp). Although the anterior leaflet takes up a larger part of the ring and rises higher, the posterior leaflet has a larger surface area. The valve leaflets are prevented from prolapsing into the left atrium by the action of chordae tendineae. The chordae tendineae are