Final answer:
The structure described is the mitral valve, which has two cuplike leaflets and is located between the left atrium and left ventricle.
Step-by-step explanation:
The structure described is the mitral valve. It has two cuplike leaflets and is located at the opening between the left atrium and left ventricle. The mitral valve, also known as the bicuspid valve, is one of the atrioventricular valves that ensure unidirectional blood flow through the heart.