What valve lies between the left atrium and left ventricle?

• A. Bicuspid (Mitral)
• B. Tricuspid
• C. Aortic semilunar
• D. Pulmonary semilunar

Answer: (A)

The valve between the left atrium and left ventricle is the mitral valve, also called the bicuspid valve. It’s one of the atrioventricular valves that opens to let blood flow from the atrium into the ventricle during the heart’s relaxation phase, and it closes when the ventricle contracts to prevent blood from flowing backward into the atrium. The term bicuspid refers to its two leaflets. The other valves are located elsewhere: the tricuspid valve sits between the right atrium and right ventricle, the aortic semilunar valve is at the outlet of the left ventricle into the aorta, and the pulmonary semilunar valve is at the outlet of the right ventricle into the pulmonary artery.