bicuspid valve (left atrioventricular valve; mitral valve) A valve, consisting of two flaps, situated between the left atrium and the left ventricle of the heart of birds and mammals. When the left ventricle contracts, forcing blood into the aorta, the bicuspid valve closes the aperture to the left atrium, thereby preventing any backflow of blood. The valve reopens to allow blood to flow from the atrium into the ventricle. Compare tricuspid valve.

mi·tral valve • n. Anat. the valve between the left atrium and the left ventricle of the heart, consisting of two tapered cusps.

mitral valve (bicuspid valve) n. a valve in the heart consisting of two cusps attached to the walls at the opening between the left atrium and left ventricle. It allows blood to pass from the atrium to the ventricle, but prevents any backward flow.

mitral valve See bicuspid valve.