The coronary sinus opens into the right atrium between which two structures, and receives which major venous tributary that drains the posterior wall of the left ventricle?

• A Opens between the superior vena cava and the fossa ovalis; receives the great cardiac vein
• B Opens between the inferior vena cava orifice and the tricuspid valve orifice; receives the left posterior ventricular vein ✓
• C Opens between the tricuspid and mitral valve orifices; receives the small cardiac vein
• D Opens at the atrioventricular junction; receives the anterior cardiac veins

Explanation

The coronary sinus, the largest venous channel of the heart, lies in the posterior atrioventricular groove and opens into the right atrium between the IVC orifice and the tricuspid valve orifice, guarded by the Thebesian valve. Its tributaries include: the great cardiac vein (anterior), small cardiac vein (right marginal), middle cardiac vein (posterior IV groove), left posterior ventricular vein (left posterior LV wall), and oblique vein of Marshall (posterior LA). The left posterior ventricular vein specifically drains the diaphragmatic (inferior) surface of the left ventricle. The anterior cardiac veins drain directly into the right atrium, bypassing the coronary sinus.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.