Which structures provide entrances to the right atrium?

Which structures provide entrances to the right atrium?

• A. Coronary sinus, superior vena cava, and inferior vena cava
• B. Aorta
• C. Pulmonary veins
• D. Pulmonary arteries

Answer: (A)

The right atrium receives venous blood from the systemic circulation and the heart muscle itself through three main entrances: the superior vena cava, the inferior vena cava, and the coronary sinus. The superior vena cava brings blood from the head, neck, and upper limbs; the inferior vena cava brings blood from the lower body; and the coronary sinus drains the myocardium’s own veins. All three channels deliver deoxygenated blood into the right atrium to be moved onward to the right ventricle and then to the lungs for oxygenation. The other vessels don’t deliver blood into the right atrium: the pulmonary veins return oxygenated blood from the lungs to the left atrium, the pulmonary arteries carry deoxygenated blood from the right ventricle to the lungs, and the aorta distributes blood from the left ventricle to the systemic circulation.

The right atrium receives venous blood from the systemic circulation and the heart muscle itself through three main entrances: the superior vena cava, the inferior vena cava, and the coronary sinus. The superior vena cava brings blood from the head, neck, and upper limbs; the inferior vena cava brings blood from the lower body; and the coronary sinus drains the myocardium’s own veins. All three channels deliver deoxygenated blood into the right atrium to be moved onward to the right ventricle and then to the lungs for oxygenation.

The other vessels don’t deliver blood into the right atrium: the pulmonary veins return oxygenated blood from the lungs to the left atrium, the pulmonary arteries carry deoxygenated blood from the right ventricle to the lungs, and the aorta distributes blood from the left ventricle to the systemic circulation.