Question

In rabbit, the opening of coronary sinus into the left precaval vein is bound by a fold called
A. Valve of Thebesius
B. Mitral valve
C. Tricuspid valve
D. Valve of Eustachian

Answer 1

Hint: In rabbits, the coronary arteries and coronary veins are present in the coronary sulcus which is present between right and left ventricles. The coronary arteries supply pure blood to the heart while coronary veins collect impure blood from the heart. The coronary veins join to form the coronary sinus.

Complete answer:
• The mitral valve is also called a bicuspid valve and it guards the opening of the left atrium into the left ventricle.
• It has two flaps that is why it is called bicuspid.
• The tricuspid valve guards the opening of the right atrium into the right ventricle.
• Tricuspid valve is made up of three flaps
• The opening of the inferior vena cava is guarded by the valve of the Eustachian or Eustachian valve.
• Pulmonary aorta and systemic aorta
• Three semilunar valves at the base which prevents the backward flow of blood during ventricular diastole(relaxation).
• In the heart, the chordae tendineae prevents the valves from turning back into the atria during the ventricular systole (contraction).
• The valve is an anatomical structure that functions to temporarily close a passage or orifice, permitting movement of fluid in only one direction. Valves may consist of muscle sphincters or membranous flaps.
• Since the bicuspid and tricuspid valves are guarding the atrio-ventricular opening within the left and right regions of the heart respectively and the Eustachian valve guards the opening of inferior vena cava.

Hence, the correct answer is option (A).

Note: The Thebesian valve is a semi-circular remnant of the embryologic sinoatrial valve, in most cases membranous in composition, and is located at the medial aspect of the posterior, inferior wall of the right atrium right at the opening of the coronary sinus.