Semilunar Valve

What are the Semilunar Valves?

The heart is one of the most important organs of the human body and it is made up of complex and intricate parts that help in the proper and correct functioning of the organ. One of the most important parts of the heart would have to be the valves that are present.


These are the structures that ensure the proper and even flow of blood in the correct direction in the body of a human being. These valves are composed mainly of different connective tissues and also have another very important part known as the endocardium. The endocardium is an inner layer that is present in the heart. In this article, students are going to learn more about the semilunar valves.

Semilunar Valves of the Heart

We all know that valves of the heart have a very important function to play and that is to ensure even and proper blood flow into the heart and that too in one direction. Well, there are 4 types of valves and they are divided into 2 different groups known as the atrioventricular valves and the semilunar valves.

The atrioventricular valves are the ones that are composed of the mitral or the bicuspid valve and the tricuspid valve. These are located mostly in the corresponding ventricles and the atria, hence the name.

The Semilunar valves compose of the aortic valve and the pulmonary valve. These valves are located right between the ventricles as well as the artery that is corresponding to them. The main function of the pulmonary and the aortic Semilunar valve is to regulate the blood flow that leaves our heart.

Semilunar Valves Location

When it comes to the Semilunar valves of the heart, there are some details that students need to know about. For example, the location of these semilunar valves is right between the outflow vessels of the heart and the ventricles. The closing happens right at the beginning of the diastole or the ventricular relaxation. This is what makes the second sound of the heart. We will be going into some more detail about the Semilunar valves that will provide a deeper understanding of the topic to the students.

What are the 2 Semilunar Valves?

We all are familiar with the fact that there are 2 different types of valves that make up the semilunar valves. These valves are known as the pulmonary and the aortic Semilunar valves.

  • Pulmonary Semilunar Valves

One of the most important things to keep in mind about the pulmonary Semilunar valves is that these are situated right between the pulmonary trunk (also known as the pulmonary orifice) and the right ventricle of the heart. There are 3 different cusps that are a part of the pulmonary valve and these are the anterior, left, and right cusps. These cusps are named by the position that they tend to have in a fetus before the rotation of the heart takes place.

  • Aortic Semilunar valves

Another part of the Semilunar valves of the heart would have to be the aortic Semilunar valves. These are the valves that are situated right between the ascending aortas (or more commonly known as the aortic orifice) and the left ventricle of the heart. This particular valve also consists of 3 different cusps which are known as the posterior, left, and right cusps.

With the left as well as the right aortic tissue, the right and left coronary arteries are formed. During the recoiling of the blood that happens in the ventricular diastole, the blood is filled in the aortic sinuses and it can enter the coronary arteries from there so that it can be supplied to the myocardium. This is one of the main semilunar valves function examples that you need to know about. We are going to be talking more about it later.

The structure of the aortic and pulmonary Semilunar valves is pretty much the same. There are certain sides that are present in each of the valves and they are connected to the walls that are present in the outflow vessels. These vessels are dilated in order to form the particular sinus.

Semilunar Valves Function

Here we are going to discuss further the semilunar valve function. Well, these valves help in determining the correct direction and method of blood passage that happens between the main arteries and ventricles of the body. Hence, it also has a very important role to play in transporting the blood from the heart to other important organs of the body. These valves make sure that the blood flow is even and is transporting without any difficulty. A proper understanding of the Semilunar valves can allow scientists and doctors to come up with several important clinical therapies that can help in the treatment process for certain degenerative and congenital diseases.

FAQs (Frequently Asked Questions)

Q1. What are the 2 Semilunar Valves?

Ans. We all know that there are 4 different valves that are present in the human heart. These are further divided into 2 categories known as the atrioventricular valves and the Semilunar valves. The Semilunar valves are further divided into 2 different types. These types are known as the pulmonary semilunar valve and the aortic semilunar valve. These valves are made up of certain connective tissues and these help in the regulation of the blood that is further pumped into all of the important organs of the human body. The structure of these valves are pretty much the same and they both consist of 3 different cusps each that further help gives them the defining structure that they have.

Q2. Where are the Semilunar Valves Located?

Ans. There are 2 important valves that make up the entire semilunar valves section of the heart and these are known as the pulmonary and the aortic semilunar valve. One of the important things to know about the locations of these essential semilunar valves is that these are situated right in the middle of the outflow vessels that are present in the heart and the important ventricles. There is closing right in the starting of the diastole which is also known as ventricular relaxation. This act assists in the formation of the second sounds that the heart tends to make.