The normal mitral valve permits unrestricted ... known as primary MR (or “organic” MR), or due to dilation of the mitral valve annulus associated with impaired left ventricular function ...

the mitral annulus, 2) the mitral valve leaflets, 3) the commissures, 4) chordae tendineae and 5) papillary muscles. The typical normal adult mitral valve area is between 4 and 5 cm 2.