Dr. Jim knew this victim was suffering from cardiac tamponade due to blood in the pericardial space. The blood in the pericardial cavity compressed the heart, squeezing the atria and ventricles so the atria could not fill. What vessels fill the right atria?

The correct answer is - The coronary sinus and superior/inferior vena cava fill the right ventricle and right atrium.

Explanation:

The right chambers of the heart receive the blood from the all over the body except lungs by the vena cava and the coronary sinus. Superior and inferior vena cava carries the blood that has no oxygen in it, from the body to the right atria which ultimately moves right ventricles and finally completes its circuit by reaching the lungs to picking the oxygen again.

On the other hand, the left atrium receives the blood from the pulmonary veins from the lungs that carry oxygen and move to the left ventricle and pump out all over the body.

Thus, the correct answer is - the coronary sinus and superior/inferior vena cava fill the right ventricle.