What is the mitral apparatus?
“Mitral apparatus” is the term used to describe the mitral valve and its structures. There are six components: the left atrial wall, the left ventricular wall, the mitral annulus, the mitral leaflets, the chordae tendineae and the papillary muscles. The components work together to ensure that the mitral valve opens and shuts correctly, which enables blood to flow through to vital organs of the body.
What is the left atrial wall?
The left atrial wall is the inside surface of the left upper chamber of the heart, the left atrium. The atrium’s wall is smooth and muscular and consists of three layers – endocardium, myocardium and epicardium. It extends proximally over the posterior mitral leaflet. For this reason, an enlarged left atrium can affect the leaflet and cause mitral regurgitation. Since the anterior leaflet attaches to the aorta’s root, it is not affected.
What is the mitral annulus?
The mitral valve annulus is a malleable ring that attaches to the mitral valve’s leaflets and intimate structures. While the annulus is often referred to as a ring, it isn’t really round; it takes the shape of a horse saddle, almost. The function of the mitral annulus is to support the mitral leaflets and facilitate blood flowing through the mitral valve. During systole, it acts as a sphincter, contracting to ensure proper closure of the leaflets.
What are the mitral leaflets?
The mitral valve leaflets (cusps) are two pliable tissue flaps (the anterior cusp and posterior cusp) that attach to the mitral valve’s annulus. They act as a doorway between the heart’s left atrium and ventricle, opening and closing tightly at just the right time to ensure that blood only flows in one direction. When one or more leaflets is damaged or in some way abnormal, mitral regurgitation and/or mitral valve prolapse can occur.
What are the chordae tendineae?
The mitral chordae tendineae (tendinous chords) are fibrous string-like bands (they are sometimes referred to as heart strings) that join the cusps of the mitral valve to the two papillary muscles located in the walls of the left ventricle. The functions of the chordae are to facilitate opening and closing of the valve and prevent blood from leaking back (regurgitating) into the left atrium during the cardiac cycle.
What are the papillary muscles?
The mitral papillary muscles are two practical muscles (the anterior and posterior) bound to the walls of the left ventricle that attach to the mitral valve’s leaflets through the heart strings or chordae tendineae. When the mitral valve closes due to blood pressure during systole, these muscles support the chordae tendineae as they tense up, preventing prolapsing of the leaflets and regurgitation of blood back into the left atrium.
What is the left ventricular wall?
The left ventricular wall is the inner surface of the left lower chamber of the heart, the left ventricle. The ventricle’s wall, like that of the left atrium’s, is also made up endocardium, myocardium and epicardium. Unlike the atrium, though, it holds the two functional muscular components (the papillary muscles) that support the chordae tendineae and leaflets. This ensures proper blood flow and function the mitral valve.