High Quality Content by WIKIPEDIA articles! Classical thermodynamics, Thermodynamic diagrams, Parametrization (climate), Ideal gas law, Entropy, Phase transitions. The mitral valve is composed of two valve leaflets, the mitral valve annulus, the papillary muscles (which tether the valve leaflets to the left ventricle, preventing them from prolapsing into the left atrium), and the chordae tendineae (which connect the valve leaflets to the papillary muscles). A dysfunction of any of these portions of the mitral valve apparatus can cause mitral regurgitation