Final answer:
The left AV valve is known as the mitral valve or bicuspid valve and it has two flexible cusps.
Step-by-step explanation:
The left AV valve, the mitral valve also known as the bicuspid valve, has two flexible cusps. The mitral valve is located at the opening between the left atrium and left ventricle of the heart, serving as a one-way gate to allow blood to flow from the atrium to the ventricle without backflow. Unlike its counterpart on the right side of the heart, the tricuspid valve, which has three cusps, the mitral valve comprises only two flaps of tissue: the anterior medial cusp and the posterior medial cusp. These cusps are attached by chordae tendineae to the papillary muscles that project from the ventricle's wall, helping to prevent the valve from inverting during ventricular contraction.