Coronary' sinus is guarded by -

Ans. is 'b' i.e., Thebesian valveo Thebesian valve (incomplete semilunar valve) guards the orifice of coronary sinus.Venous Drainage of Hearto 60 % through coronary sinus into right atriumo 40 % directly in chambers of the heart via.Anterior cardiac veinsThebesian vein or venae cordis minimiSometimes, the right marginal vein opens directly into right atriumCoronary Sinuso It is a 2-3 cm long venous channel present in left posterior part of coronary sulcuso It opens into the sinus venorum part of right atrium, the opening guarded by incomplete semilunar valveTributariesGreat cardiac vein : It runs in the anterior interventricular groove and receives the left marginal vein.Middle cardiac vein : It lies in the posterior interventricular groove.Small cardiac vein : It is present in the atrioventricular groove and usually receives the right marginal vein.Posterior vein of left ventricle : It drains the inferior surface of the left ventricle.Oblique vein of left atrium : It drains the posterior surface of left atrium (a remnant of the left duct of cuvier)Note : All the above veins are provided with valves except oblique vein of left atrium.