Heart Wall Anatomy | Structure of the Heart Wall
Heart Valves: Anatomy and Function
Introduction to the Anatomy of the Heart Valves:
Four valves maintain the unidirectional flow of blood through the heart. The valves are located between the atria and ventricles and in the two arteries that empty blood from the ventricles.
They are composed mostly of fibrous connective tissue that extends from the heart walls. The external surfaces of the valves are covered by endocardium.
- The right atrioventricular valve (or AV valve) controls blood flow from the right atrium to the right ventricle.
Because it is composed of three cusps or flaps this valve is also called the tricuspid valve.
- The left atrioventricular valve (or AV valve) controls blood flow from the left atrium to the left ventricle.
It is made up of two cusps or flaps, so it is often called the bicuspid valve. The term mitral valve is also commonly applied because the left AV valve is shaped somewhat like a bishop’s miter (L., mitra, headdress).
The chordae tindineae and papillary muscles tether the AV valves to the ventricular walls. This allows the valves to close properly and not bulge (or prolapse) into the atria.
- Semilunar valves (L., semis, half + luna, moon) direct blood flow from the ventricles into the aorta and pulmonary trunk artery.
The valves are located in the vessels just above the openings to ventricles and consist of three cusps that curve upward to form a small pocket.