All open coronary sinus except?: (A) Middle cardiac vein, (B) Anterior cardiac vein, (C) Small cardiac vein, (D) Great cardiac vein
Answer is B. Ans. B. Anterior cardiac veinThe coronary sinus is a collection of veins joined together to form a large vessel that collects blood from the heart muscle. The coronary sinus drains into the right atrium, at the coronary sinus orifice, an opening between the inferior vena cava and the tricuspid valve. It returns blood from the heart muscle, and is protected by a semicircular fold, the valve of coronary sinus (Thebesian valve).