The heart contains four valves: the pulmonary, aortic, mitral, and tricuspid. The valves all open and close, allowing blood to flow throughout the heart and body. The boll-shaped segments which open and close are called cusps. Cusps open to allow blood flow outward, but they can be sealed tight, withholding any blood from coming in. Some valves are composed of two cusps, and some have three. The picture shows the difference between the two types.
|You will see this labeled illustration in many places across the site. Click on any of the labels for a description of the specific part.||
The pulmonary valve guards the opening of the right ventricle. It regulates the blood flow out of the heart and into the pulmonary artery. The pulmonary valve contains three cusps.Aortic
The aortic valve is located between the left ventricle and the aorta. It allows blood to flow into the aorta, but not back. The aortic valve, like the pulmonary valve, is composed of three cusps.Mitral
The mitral valve is the only valve found in the heart with only two cusps. It is also much larger than the aortic and pulmonary valves. The mitral valve is located between the left ventricle and left atrium, and it allows blood to flow to the latter. It is connected to the ventricular walls with fibrous strands called chordae tendineae.Tricuspid
The tricuspid valve opens to allow blood to flow from the right ventricle to the right atrium. It shares similarities with the mitral valve. It has a similar size and is connected to the ventricular walls with chordae tendineae. However, the tricuspid valve has three cusps, while the mitral has only two.