What is the function of the bicuspid valve?

Mitral valve: Bicuspid means "two leaflets". The only "normal" bicuspid valve in the heart is the mitral valve. It sits between the left atrium and left ventricle. The valve opens to fill the left ventricle during diastole and closes when the ventricle contracts (systole). The aortic valve is normally tricuspid but some people are born with an abnormal and bicuspid valve which may narrow later in life...

Control blood flow: All valves function the same. They are flaps of very strong tissue that open one way to allow blood to flow in one direction. The valve closes to prevent back-flow of blood into the chamber it just left. The bicuspid valve (bi- means two, cusp means flap) is more commonly called the mitral valve. It separates the left atrium from the left ventricle.