Coronary Veins 
 
Coronary veins are the blood vessels that drain deoxygenated blood from the myocardium (heart muscle) and return it to the right atrium of the heart. The veins run alongside the coronary arteries but carry blood in the opposite direction. 
 
 Major Coronary Veins 
 
1. The Coronary Sinus 
 
The largest vein of the heart. 
Located in the posterior part of the coronary sulcus (between the left atrium and left ventricle; and sits at the back of the heart). 
Receives blood from the great, middle, small, posterior, and oblique veins. 
Drains into: The right atrium, near the opening of the inferior vena cava. 
 
2. Great Cardiac Vein 
Location: Runs alongside the anterior interventricular artery (left anterior descending artery; serves the left atrium and left ventricle). 
 
3. Middle Cardiac Vein (Posterior Interventricular Vein) 
Location: Runs in the posterior interventricular sulcus, alongside the posterior interventricular artery (serves the right ventricle)  
 
4. Small Cardiac Vein 
Location: Runs along the right margin of the heart with the right coronary artery (serves the right atrium and right ventricle). 
 
 
Source: Radiopedia.