What nourishes the myocardium?

• A. Coronary arteries
• B. Aorta
• C. Pulmonary arteries
• D. Coronary sinus

Answer: (A)

Nourishment for the myocardium comes from the coronary arteries. The heart muscle has high energy demands and relies on the coronary circulation, which arises from the ascending aorta just above the aortic valve, delivering oxygen-rich blood to the myocardium through its capillary networks. When these arteries are blocked, the myocardium suffers ischemia, leading to a heart attack.

The aorta mainly carries blood to the body, and while coronary arteries originate from it to feed the heart, the aorta itself isn’t the direct nourish-for-the-muscle vessel. The pulmonary arteries move blood from the right ventricle to the lungs for gas exchange, not to the heart muscle. The coronary sinus drains venous blood from the heart back into the right atrium, serving as a drainage pathway rather than a source of nourishment.