What is the mitral apparatus?
“Mitral apparatus” is the term used to describe the mitral valve and its structures.
There are six components that make up the mitral apparatus in the human heart. These are the left atrial wall, the left ventricular wall, the mitral annulus, the mitral valve leaflets or cusps, the chordae tendineae, and the papillary muscles.
The components of the mitral apparatus work together to ensure that the mitral (aka buscuspid) valve opens and shuts correctly, which enables blood to flow through to vital organs of the body for proper function.
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, namely endocardium, myocardium, and epicardium. It extends proximally over the posterior mitral leaflet.
For this reason, an enlarged left atrium can affect the bicuspid valve’s 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 structures. Though often referred to as a ring, it isn’t actually round. It is similar in shape to a horse saddle.
The function of the annulus is to support the mitral cusps and facilitate blood flowing through the 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 are two pliable tissue flaps (these are referred to as the anterior cusp and posterior cusp) that attach to the bicuspid valve’s annulus ring.
Opening and closing tightly at just the right time to ensure that blood only flows in one direction, the cusps act as a doorway between the heart’s left atrium and ventricle.
When one or more mitral leaflets is damaged or in some way abnormal, mitral regurgitation and/or mitral valve prolapse may occur, which can lead to problems and complications.
What are the chordae tendineae?
The chordae tendineae are fibrous, string-like bands (sometimes called 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 bicuspid valve and prevent blood from leaking back (regurgitating) into the left atrium during the cardiac cycle.
What are the papillary muscles?
The papillary muscles are two 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 during systole, the papillary muscles support the chordae 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 made up endocardium, myocardium, and epicardium.
Unlike the atrium, though, it holds two functional components (the papillary muscles) that support the chordae tendineae and leaflets. This ensures proper blood flow and function the mitral valve.