Difference Between Tricuspid and Bicuspid Valve

The main difference between tricuspid and bicuspid valve is that the tricuspid valve is located between the right atrium and right ventricle whereas bicuspid valve is located between the left atrium and left ventricle. Furthermore, the tricuspid valve consists of three cusps while bicuspid valve consists of two cusps.

Tricuspid and bicuspid valves are the two types of atrioventricular (AV) valves of the heart that prevent the reverse flow of blood from the ventricles to the atria.

Key Areas Covered

1. What is Tricuspid Valve
     – Definition, Location, Role
2. What is Bicuspid Valve
     – Definition, Location, Role
3. What are the Similarities Between Tricuspid and Bicuspid Valve
     – Outline of Common Features
4. What is the Difference Between Tricuspid and Bicuspid Valve
     – Comparison of Key Differences

Key Terms

Atrioventricular Valves (AV), Atria, Bicuspid Valve, Cusps, Mitral Valve, Tricuspid Valve, Ventricles

What is Tricuspid Valve

The tricuspid valve is the right AV valve found between the right atrium and right ventricle. It is made up of three cusps supported by chordae tendineae, the fibrous cords. These fibrous cords are continuous with the papillary muscles that are attached to the anterior surface of the ventricles. Papillary muscles prevent the prolapse of cusps into the atria. Altogether, there are five papillary muscles in the heart and three of them are attached to the chordae tendineae of the tricuspid valve.

Figure 1: Heart Valves

The right ventricle is much smaller in size when compared to the right atrium. Therefore, when pumping blood from the right atrium to the right ventricle, a huge pressure is generated. In order to withstand this high pressure, the right AV valve is made up of three cusps.

What is Bicuspid Valve

The bicuspid valve is the left AV valve, found between the left atrium and left ventricle. This valve is also called the mitral valve. It is made up of two cusps. These cusps are also supported by the fibrous cords. The main function of the bicuspid valve is to allow the flow of blood to the left ventricles from the right ventricles. It prevents the reverse flow of blood towards the left atrium during the contraction of the heart to pump blood from the heart to the aorta.

Figure 2: Blood Flow of the Heart

Similarities Between Tricuspid and Bicuspid Valve

• Tricuspid and bicuspid valves are the two types of AV valves of the heart.
• They are made up of endocardium and connective tissue.
• Both are located between the atrium and ventricle.
• The cusps of each valve are anchored to fibrous cords, surrounding the orifice.
• They close at the start of the ventricular contraction, making the first heart sound, which is called lub sound or S1.
• Both allow the blood to flow from atria to the ventricles but, prevent the reverse flow of blood from the ventricles to the atria.

Difference Between Tricuspid and Bicuspid Valve

Definition

Tricuspid valve refers to the valve that is situated between the right atrium and right ventricle while bicuspid valve refers to the valve between the left atrium and the left ventricle of the heart.

Significance

While tricuspid valve is the right atrio-ventricular valve, bicuspid valve is the left atrio-ventricular valve.

Number of Cusps

Furthermore, another difference between tricuspid and bicuspid valve is that the tricuspid valve consists of three cusps while bicuspid valve consists of two cusps.

Papillary Muscles

The papillary muscles attached to the tricuspid valve are the anterior, posterior, and septal papillary muscles while the papillary muscles attached to the bicuspid valve are anterolateral and posteromedial papillary muscles.

Function

Concerning the function, the tricuspid valve prevents the reverse flow of blood from the right ventricle to the right atrium while bicuspid valve prevents the reverse flow of blood from the left ventricle to the left atrium.

Type of Blood

The deoxygenated blood flows through the tricuspid valve while oxygenated blood flows through the bicuspid valve. 

Conclusion

Tricuspid valve is the right atrio-ventricular valve of the heart, which allows the flow of blood from the right atrium to the right ventricle. On the other hand, bicuspid valve is the left atrio-ventricular valve, which allows the flow of blood left atrium to the left ventricle. Tricuspid valve consists of three cusps while bicuspid valve consists of two cusps. The main difference between tricuspid and bicuspid valve is their location and function.

Reference:

1. “The Valves of the Heart.” TeachMeAnatomy, 22 Dec. 2017, Available Here

Image Courtesy:

1. “2011 Heart Valves” By OpenStax College – Anatomy & Physiology, Connexions Web site, Jun 19, 2013. (CC BY 3.0) via Commons Wikimedia    
2. “Diagram of the human heart (cropped)” By Wapcaplet – Own work (CC BY-SA 3.0) via Commons Wikimedia