The openings of the right and left ventricles into the pulmonary artery and the aorta respectively are provided with which of the following structures?

Step-by-step solution

The opening between the right ventricle and the pulmonary artery is guarded by the pulmonary semilunar valve. The opening between the left ventricle and the aorta is guarded by the aortic semilunar valve. These valves prevent the backflow of blood from the arteries into the ventricles. The mitral valve (bicuspid valve) guards the opening between the left atrium and the left ventricle. The tricuspid valve guards the opening between the right atrium and the right ventricle. The Eustachian valve guards the opening of