(i) Bicuspid valve: Bicuspid ventricle is located between left atrium and ventricle. This is called mitral regurgitation. It is attached to the columnar corni by corda tendon fibers. Its size is 4-6 square cm. It allows O2-rich blood to flow from the left atrium to the left ventricle.
(ii) Tricuspid valve: The tricuspid valve is located between the right atrium and ventricle. It is attached to the columnar corni by corda tendon fibers. Its size is 7-9 square cm. It allows blood containing CO2 to flow from the right atrium to the right ventricle.
(iii) Pulmonary semilunar valve: The crescent-shaped valve between the right ventricle and the pulmonary artery is called the pulmonary semilunar valve. It has three screens. But can be bi-veined (1-2). Through this valve, blood containing CO2 enters the pulmonary artery from the right ventricle.
(iv) Aortic semilunar valve: The crescent-shaped valve between the left ventricle and the aortic artery is called the aortic semilunar valve. It has three screens. O2-rich blood enters the aortic artery from the left ventricle through this valve.
(v) Coronary valve: Between the coronary sinus and the right atrium lies the Thibesian valve. It is the atrophy of the fetal sino-atrial septum. In many cases it is absent.
(vi) Eustachian tube: It lies between the inferior vena cava and the right atrium. Blood containing CO2 enters the right atrium through this ventricle. The Italian physician Bartolomeo Eustachi discovered the capsule.