What is the function of the Coronary Sinus?

What is the function of the Coronary Sinus?

• A. It collects venous blood and drains deoxygenated blood from the heart wall into the right atrium.
• B. It supplies oxygenated blood to the myocardium
• C. It drains blood from the lungs into the left atrium
• D. It returns blood from the lower limbs to the right atrium

Answer: (A)

The main concept here is venous drainage of the heart muscle. The coronary sinus is the main vein that collects deoxygenated blood from the myocardium and returns it to the right atrium. It runs along the posterior aspect of the heart in the coronary sulcus and opens into the right atrium, delivering blood from the cardiac veins (great, middle, small, and other veins) after they have delivered oxygen to the heart tissue via the coronary arteries. This blood is deoxygenated, which is why it goes back into the right atrium to join the systemic venous return. It’s not a source of oxygenated blood to the heart muscle—that’s the role of the coronary arteries. It also doesn’t drain blood from the lungs into the left atrium (that’s the pulmonary veins), nor does it return blood from the lower limbs to the right atrium (that’s the inferior vena cava and other systemic veins).

The main concept here is venous drainage of the heart muscle. The coronary sinus is the main vein that collects deoxygenated blood from the myocardium and returns it to the right atrium. It runs along the posterior aspect of the heart in the coronary sulcus and opens into the right atrium, delivering blood from the cardiac veins (great, middle, small, and other veins) after they have delivered oxygen to the heart tissue via the coronary arteries. This blood is deoxygenated, which is why it goes back into the right atrium to join the systemic venous return.

It’s not a source of oxygenated blood to the heart muscle—that’s the role of the coronary arteries. It also doesn’t drain blood from the lungs into the left atrium (that’s the pulmonary veins), nor does it return blood from the lower limbs to the right atrium (that’s the inferior vena cava and other systemic veins).