Functional Anatomy of the Heart Valves

1. General Principles

The heart contains four valves that ensure unidirectional blood flow during the cardiac cycle. They are divided into Atrioventricular (AV) and Semilunar valves.

2. Atrioventricular Valves

• Tricuspid Valve: Located between the right atrium and right ventricle. It has three leaflets (Anterior, Posterior, Septal).
• Mitral (Bicuspid) Valve: Between the left atrium and left ventricle. It has two leaflets and is the most common site for valvular heart disease.
• Chordae Tendineae & Papillary Muscles: These structures prevent the inversion (prolapse) of the valves into the atria during ventricular contraction.

3. Semilunar Valves

• Aortic Valve: Prevents backflow from the aorta into the left ventricle.
• Pulmonary Valve: Prevents backflow from the pulmonary trunk into the right ventricle. These valves consist of three pocket-like cusps and lack chordae tendineae.

4. Clinical Correlations

• Mitral Valve Prolapse (MVP): Occurs when the leaflets bulge into the left atrium, potentially causing mitral regurgitation.
• Aortic Stenosis: Narrowing of the aortic valve, often due to calcification, leading to left ventricular hypertrophy.

5. Review

1. Which valve is bicuspid?
2. What is the function of the papillary muscles?
3. During which phase of the cardiac cycle do the semilunar valves open?