The coronary sinus is a collection of veins that together form one large vessel to collect blood from the myocardium of the heart. The right atrium receives deoxygenated blood from coronary sinus.
The tributaries of the coronary sinus are: the left marginal vein, the left posterior ventricular vein, and the cardiac veins (small, middle, great, and oblique).
The left marginal vein receives its blood from the left atrium, and both ventricles. The left poster ventricular vein runs along the diaphragmatic surface of the left ventricle receiving its blood from the left atrium as well. The cardiac veins also receive their blood from the left atrium and both ventricles, their names referring to their locations: great (begins at the apex of the heart and goes along the anterior longitudinal sulcus), small (runs along the coronary sculls), middle (starts at the apex of the heart and runs along the posterior longitudinal sulcus), and oblique (descends obliquely on the back of the left atrium).