Which heart valve prevents backflow into the left atrium?

The mitral valve, also known as the bicuspid valve, is responsible for preventing the backflow of blood into the left atrium from the left ventricle during ventricular contraction. When the left ventricle pumps blood into the aorta, the mitral valve closes tightly to ensure that all the blood flows forward into the aorta and does not re-enter the left atrium. This function is crucial for maintaining proper circulation and ensuring that the heart functions efficiently, as any backflow could disrupt the flow of blood through the heart and to the body's tissues.

In contrast, the tricuspid valve is positioned between the right atrium and right ventricle, the pulmonary valve is found between the right ventricle and the pulmonary artery, and the aortic valve is located between the left ventricle and the aorta. Each of these valves serves specific roles in regulating blood flow through their respective heart chambers and vessels but do not prevent backflow into the left atrium.