The great cardiac vein is a large blood vessel which drains a vast area of anterior aspect of heart, which includes the left and right ventricle and left atrium. It begins on the anterior surface of apex of the heart. Then it runs up in the anterior interventricular groove, parallel to the anterior interventricular branch of left coronary artery. When it reaches the atrioventricular groove, it turns left, running alongside the circumflex branch of left coronary artery in the atrioventricular groove.
As it winds around the left border of the heart, the great cardiac vein travels in the posterior portion of the atrioventricular groove, ending up in the coronary sinus. Along its course, the great cardiac vein receives deoxygenated blood from important tributary branches, which contribute to drain about 65% of the heart. The coronary sinus is basically the dilated final portion of the great cardiac vein, receiving deoxygenated blood from the middle cardiac and the small cardiac vein as it empties into the right atrium.
Below, the great cardiac vein on anterior side of heart
Posterior aspect.
