Superior vena cava opens into right atrium at the level of –

**Core Concept**
The superior vena cava (SVC) is a major vein that returns deoxygenated blood from the upper body to the heart. The SVC is formed by the union of the left and right brachiocephalic veins and drains into the right atrium (RA) of the heart. Understanding the anatomical relationship between the SVC and the RA is crucial for diagnosing and managing various cardiovascular conditions.

**Why the Correct Answer is Right**
The SVC opens into the RA at the level of the inferior vena cava (IVC) entrance, which is also known as the coronary sinus ostium. This occurs at the level of the tricuspid valve, specifically at the junction of the SVC and the RA. The SVC's entry point is located on the anterior (front) surface of the RA, near the middle of the right atrium. The SVC's opening is guarded by the valve of the inferior vena cava, which prevents backflow of blood from the RA into the SVC.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the SVC does not open into the left atrium, which is located on the opposite side of the heart from the RA.

**Option B:** This option is incorrect because the SVC does not enter the right ventricle, which is located below the RA and receives oxygenated blood from the left atrium.

**Option C:** This option is incorrect because the SVC does not enter the pulmonary artery, which is located in the pulmonary trunk and carries deoxygenated blood from the right ventricle to the lungs.

**Clinical Pearl / High-Yield Fact**
The valve of the inferior vena cava, also known as the Eustachian valve, is a vestigial structure that can sometimes be mistaken for a tumor or a thrombus on imaging studies. It is a normal anatomical variant that can be seen on echocardiography or cardiac MRI.

**Correct Answer:** C.