Right coronary sinus directly drains into

The coronary sinus is the largest vein of the hea.It is situated in the left posterior coronary sulcus.It is about 3cm long.It ends by opening into the posterior wall of the right atrium.It receives the following tributaries such as the great cardiac vein,the middle cardiac vein,the small cardiac vein,the posterior vein of the left ventricle,the oblique vein of the left atrium of Marshall and the right marginal vein. REF.B D Chaurasia's human anatomy vol.1,fifth edition