The cardiac veins carry deoxygenated blood from the myocardium to the right atrium.
- Cardiac veins are classified by their blood-flow return to the heart:
- The coronary sinus (and its four major tributaries) drains into the right atrium.
- The anterior cardiac veins drain directly into the right atrium.
- The small cardiac veins drain directly into the nearest chamber.
Pathway of venous return to the coronary sinus:
The coronary sinus is a wide, short vessel that drains directly into the right atrium. It runs in the posterior coronary sulcus.
- Four major tributaries:
- Great cardiac vein
- Left posterior ventricular vein
- Middle cardiac vein
- Small cardiac vein
Anterior interventricular vein
- Arises near the apex of the heart and travels superiorly (within the anterior interventricular sulcus).
- Once it reaches the coronary sulcus, the anterior interventricular vein becomes the great cardiac vein.
- Travels posteriorly to drain directly into the left end of the coronary sinus (be aware that some texts do not name the anterior interventricular vein separately; instead, they refer to this entire vessel as the great cardiac vein).
Right marginal vein
- Travels superiorly along the right side of the heart.
- At the coronary sulcus, the right marginal vein becomes the small cardiac vein.
- Wraps posteriorly to drain directly into the right end of the coronary sulcus (in some individuals, the right marginal vein drains directly into the right atrium).
Middle cardiac vein
- Arises near the apex and runs in the posterior interventricular sulcus (hence, it is also called the posterior interventricular vein).
Left posterior ventricular vein
- Arises between the great and middle cardiac veins.
Anterior cardiac veins
- Arise on the superior surface of the right ventricle, and drain directly into the right atrium.
Smallest cardiac veins
aka, venae cordis minimae, aka, thebesian veins
- Valveless vessels that drain directly into the cardiac chambers, particularly the right atrium.
Vein – Artery Associations:
- The anterior interventricular vein travels with the anterior interventricular artery.
- The middle cardiac vein travels with the posterior interventricular artery.
- The small cardiac vein travels with the right coronary artery.
- The right marginal vein travels with the right marginal artery.
In Summary:
The great cardiac and left posterior ventricular veins drain regions of the myocardium supplied by the left coronary artery;
The middle and small cardiac veins drain regions of the myocardium supplied by the right coronary artery.
