THORAX ABDOMEN AND PELVIS

Detailed explanation-1: -The cardiac veins like the great cardiac vein, middle cardiac vein, small cardiac vein, a posterior vein of the left ventricle drain the blood into the coronary sinus. Inferior and superior vena cava empty blood directly into the right atrium.

Detailed explanation-2: -The great cardiac vein, the middle cardiac vein, and the small cardiac vein all drain into the coronary sinus (which opens into the right atrium). The anterior cardiac veins drain directly into the right atrium.

Detailed explanation-3: -The function of the coronary sinus is to drain the venous blood from the majority of the heart. It opens into the right atrium between the opening of inferior vena cava, the fossa ovalis and the right atrioventricular orifice.

Detailed explanation-4: -The inferior and superior vena cava bring oxygen-poor blood from the body into the right atrium. The pulmonary artery carries oxygen-poor blood from the right ventricle into the lungs, where oxygen enters the bloodstream. The pulmonary veins bring oxygen-rich blood to the left atrium.