What separates the left atrium from the left ventricle?

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

Answer: (B)

The mitral valve sits between the left atrium and the left ventricle. It’s the left-sided atrioventricular valve, typically called the bicuspid valve because it has two leaflets. When the heart relaxes, the mitral valve opens to allow blood to flow from the left atrium into the left ventricle. When the ventricle contracts, the valve closes to prevent blood from flowing backward into the atrium. This boundary between the atrium and ventricle on the left side is what that structure separates.