**Question:** All of the following are seen on the right side of the cardiac silhouette in chest X-ray except: September 2008, 2010

**Core Concept:** Chest X-rays are essential investigations in clinical practice, providing valuable information about cardiac, pulmonary, and mediastinal structures. The cardiac silhouette is the outline of the heart seen on chest X-ray, which can be used to assess heart size, position, and any associated pathologies.

**Why the Correct Answer is Right:** The correct answer is **D**. The right side of the cardiac silhouette typically shows the following findings:

1. The right atrium (RA) and right ventricle (RV) are located on the right side of the cardiac silhouette.
2. The ascending aorta (AAo) and pulmonary trunk (PT) are also located on the right side, as they originate from the right side of the heart.
3. The presence of pleural effusion (fluid accumulation in the pleural space) can also be seen on the right side.

**Why Each Wrong Option is Incorrect:**

A. **Option A (September 2008)**: This option is incorrect because the left atrium (LA) and left ventricle (LV) are located on the left side of the cardiac silhouette.

B. **Option B (2010)**: This option is incorrect because it mentions the pulmonary veins (PV), which are not directly related to the cardiac silhouette on the chest X-ray. The pulmonary veins connect the lungs and the left atrium and do not contribute to the right side of the cardiac silhouette.

C. **Option C**: This option is incorrect because the pulmonary artery (PA) is part of the systemic circulation and does not contribute to the right side of the cardiac silhouette. The PA is located on the left side of the cardiac silhouette.

E. **Option D**: This option is incorrect as it mentions the right atrium (RA) and right ventricle (RV), which are located on the right side of the cardiac silhouette.

**Clinical Pearl:** The knowledge of cardiac anatomy and the right side of the cardiac silhouette on a chest X-ray is crucial for accurate interpretation and diagnosis of various cardiac and pulmonary diseases. Understanding the cardiac silhouette aids in recognizing enlarged cardiac chambers, pleural effusion, and other abnormalities affecting the right heart structures.