The coronary sinus is the main vein that drains deoxygenated blood from the heart muscle (myocardium) back into the right atrium of the heart.
Here's a more detailed explanation:
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Major Venous Drainage: The coronary sinus serves as the primary venous channel for collecting and returning blood from the heart. Think of it as the heart's main drain.
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Location: It's located on the posterior (back) surface of the heart in the atrioventricular groove (the groove that separates the atria and ventricles).
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Receiving Veins: Several veins empty into the coronary sinus, including:
- Great cardiac vein
- Middle cardiac vein
- Small cardiac vein
- Posterior vein of the left ventricle
- Oblique vein of the left atrium
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Delivery Point: The coronary sinus empties directly into the right atrium, near the opening of the inferior vena cava.
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Valve Protection: A valve, called the Thebesian valve (or valve of the coronary sinus), guards the opening of the coronary sinus into the right atrium. This valve helps prevent backflow of blood into the sinus during atrial contraction, although its effectiveness varies.
In essence, the coronary sinus plays a critical role in the heart's circulatory system by ensuring that deoxygenated blood from the heart muscle is efficiently returned to the right atrium to be re-oxygenated.
