Anatomical arrangement of muscle tissue in the anterior mitral leaflet in man.

Muscle tissue in atrioventricular (A-V) cardiac valve leaflets was studied in 35 human hearts and was found to be more prominent in the anterior leaflet of the mitral (MAL) than in the other valve leaflets. From serial sectioning and wax model reconstruction, the anatomic arrangement of the muscle in the MAL indicates bundles passing from the two commissural regions towards the mid-zone of the valve. Age did not appear to reduce the mass of muscle tissue in the MAL. The possibility of muscle contraction in the MAL increasing leaflet tension and accelerating post-artial movements received support by comparisons of the anterior and posterior leaflets of the mitral valve in their movements towards closure.