Great cardiac vein drains into –
**Core Concept**
The great cardiac vein is a key component of the coronary venous system, which plays a crucial role in draining deoxygenated blood from the myocardium. The great cardiac vein is responsible for collecting blood from the left ventricle and left atrium, and it ultimately empties into the coronary sinus.
**Why the Correct Answer is Right**
The great cardiac vein runs along the anterior interventricular groove, collecting blood from the left ventricle and left atrium. It then merges with the left marginal vein to form the coronary sinus, which is a large venous channel that collects blood from the myocardium. The coronary sinus empties into the right atrium through the coronary sinus orifice. The great cardiac vein's drainage into the coronary sinus is a critical pathway for returning deoxygenated blood to the heart.
**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because the great cardiac vein does not drain directly into the left atrium. While the left atrium does receive blood from the left ventricle, the great cardiac vein's drainage is specifically into the coronary sinus.
* **Option B:** This option is incorrect because the great cardiac vein does not drain into the coronary artery. The coronary arteries are responsible for supplying oxygenated blood to the myocardium, whereas the great cardiac vein is involved in draining deoxygenated blood.
* **Option C:** This option is incorrect because the great cardiac vein does not drain directly into the right atrium. While the right atrium ultimately receives blood from the coronary sinus, the great cardiac vein's drainage is specifically into the coronary sinus.
**Clinical Pearl / High-Yield Fact**
Remember that the coronary sinus is a critical structure in the coronary venous system, and its drainage into the right atrium is essential for returning deoxygenated blood to the heart. The coronary sinus can be a site of cardiac pathology, such as coronary sinus thrombosis or coronary sinus ostium atresia.
**Correct Answer: C. Coronary sinus**