The right border of the heart on a PA chest X-ray is formed by which structure at its lower portion?
- A Right ventricle
- B Superior vena cava
- C Right atrium ✓
- D Inferior vena cava
Correct answer: C. Right atrium
Explanation
On a PA chest X-ray, the right heart border is formed superiorly by the superior vena cava (SVC) and inferiorly by the right atrium. The right atrium forms the entire lower right border from the right cardiophrenic angle to the level where the SVC joins the atrium. The right ventricle does NOT form the right border — it is an anterior structure that forms part of the inferior border. The left heart border is formed by the aortic knuckle (aortic arch), main pulmonary artery, left atrial appendage, and left ventricle (from top to bottom).
Reference: BD Chaurasia's Human Anatomy, 8th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.