Located in the coronary sulcus between the right atrium and right ventricle, the small cardiac vein eventually coalesces with the coronary sinus on the posterior side of the heart and drains to the right atrium. The middle cardiac vein travels alongside the posterior interventricular artery in the posterior interventricular sulcus, and empties deoxygenated blood into the coronary sinus. The middle cardiac vein originates from the apex of the heart but on the posterior side. The great cardiac vein empties the blood from both ventricles and the left atrium into the right atrium. Once the vein reaches the left margin of the heart, it circumvents to the posterior side and eventually converges with the oblique vein of the left atrium into the coronary sinus.
Starting from the apex of the heart and running parallel with the anterior interventricular artery, the great cardiac vein travels up along the anterior interventricular sulcus towards the base of the left atrium’s auricle. The venous tributaries that merge into the coronary sinus include the great cardiac vein, middle cardiac vein, small cardiac vein, left posterior ventricular, and oblique cardiac vein. Located along the left posterior atrioventricular groove, the coronary sinus empties directly into the right atrium through the coronary sinus orifice. The coronary sinus is the largest cardiac vein with multiple smaller vessels converging into it. The main venous vasculature of this system includes the coronary sinus and its tributaries, marginal veins, anterior cardiac veins, ventricular veins, and atrial veins. The greater cardiac venous system returns three-quarters of the deoxygenated blood from the myocardium to the cardiac chambers. The primary physiological function of the coronary veins is to carry deoxygenated blood from the myocardium and empty them into the chambers of the heart. Coronary veins can be organized into two groups: the greater and smaller cardiac venous system. Gaining a comprehensive understanding of the anatomy of the coronary venous vasculature is thus vital to enhance clinical knowledge and aid informed physician decision-making for future cardiovascular patients. Physiological variability of coronary veins also exists among a diverse patient population. The greater cardiac venous system drains the majority of the deoxygenated blood, while the smaller cardiac venous system drains a smaller portion of the deoxygenated blood to its respective heart chambers.
Comprised of two venous systems, coronary veins classify into either the greater cardiac venous system or the smaller cardiac venous system. Coronary veins are responsible for draining deoxygenated blood from the myocardium into the cardiac chambers. As biomedical science and technology advance, coronary veins have gained significant clinical importance for treatment and intervention for cardiac patients globally. The intricacy of the coronary venous system highlights both the complexity and beauty of the human heart's anatomical features.