Heart and Thorax Anatomy MCQs

Anatomy · 38 free questions with answers & explanations.

1. The sinoatrial node is supplied predominantly by a branch of which artery in most individuals?
2. The right border of the heart on a chest radiograph is formed by which structure?
3. On a standard PA chest X-ray, the right heart border is formed by which structures from top to bottom?
4. A patient with a left-sided pleural effusion undergoes thoracocentesis. To avoid the intercostal neurovascular bundle, the needle should be inserted at which position relative to the rib?
5. The triangle of Koch is an important surgical landmark for the AV node. Which three structures form its boundaries?
6. During a modified radical mastectomy with axillary node dissection, the surgeon identifies the long thoracic nerve (nerve of Bell) on the serratus anterior. Injury to this nerve causes which deformity on clinical examination?
7. The left vagus nerve crosses the aortic arch at which specific location, giving off the left recurrent laryngeal nerve that hooks under which structure?
8. The triangle of Koch is an important surgical landmark for the atrioventricular node location in the right atrium. Which three structures define its boundaries?
9. In a stab wound to the back at the level of the 7th intercostal space in the midscapular line on the right side, which structures are encountered in sequence from superficial to deep before reaching the pleural cavity?
10. A patient undergoes coronary angiography which shows complete occlusion of the right coronary artery just after the origin of the posterior descending artery (PDA). Which areas of the heart are at risk of infarction?
11. During a central venous line insertion via the right subclavian vein approach, the needle is directed toward the sternal notch. Inadvertent arterial puncture would most likely enter which artery?
12. The oblique pericardial sinus is a blind pouch behind the heart. What structures form its boundaries, and what is its clinical significance?
13. During a right-sided thoracotomy for esophagectomy, the surgeon must identify and protect the thoracic duct. At which level does the thoracic duct cross from the right to the left side of the vertebral column?
14. Histologically, the SA node is identifiable because its cells are characteristically different from surrounding myocardium. Which histological feature is specific to the SA node cells?
15. A stab wound enters the thorax in the 4th left intercostal space in the midclavicular line. Which cardiac chamber is most likely injured?
16. After a right pneumonectomy, the surgeon notes that the right lung root structures pass anterior and posterior to the right main bronchus. Which structure passes anterior to the right main bronchus at the lung root?
17. During a pericardiocentesis performed via the subxiphoid (epigastric) route with the needle directed toward the left shoulder, which anatomical space is entered and what is the fluid's location?
18. A patient with mitral stenosis undergoes closed mitral commissurotomy via a left thoracotomy. The surgeon introduces a finger through the left atrial appendage. Through which valvular structure does the stenotic leaflet fusion most commonly occur, and which interatrial structure can the surgeon feel from within the left atrium?
19. During a left thoracotomy for esophageal surgery, the thoracic duct is at risk. At which vertebral level does the thoracic duct cross from the right side to the left side of the vertebral column?
20. A central venous catheter inserted via the right subclavian vein inadvertently pierces the pleural dome. Which structure forms the highest point of the pleural dome, and how far above the medial 1/3 of the clavicle does it extend?
21. The azygos vein drains into the superior vena cava by arching over the root of the right lung. Its clinical importance lies in its role as a collateral pathway. If the SVC is obstructed above the azygos vein entry, which statement is TRUE?
22. During pericardiocentesis (needle aspiration of pericardial effusion), the needle is inserted at the left xiphicostal angle (between xiphoid and left costal margin) and directed at 45° toward the left shoulder. Which layer is entered last before reaching the pericardial cavity?
23. During median sternotomy and coronary artery bypass grafting, the left internal thoracic artery (LITA) is harvested as a conduit. The LITA runs in close proximity to which mediastinal structure that, if damaged, causes phrenic nerve palsy?
24. The triangle of Koch on the right atrial endocardium demarcates the location of the AV node. The three boundaries of the triangle of Koch are:
25. The coronary sinus, the primary venous drainage of the heart, opens into which cardiac chamber and is guarded by which valve?
26. The left recurrent laryngeal nerve loops under which structure in the thorax, making it vulnerable to compression by aortic aneurysm, lung malignancy, or lymphadenopathy (Ortner's syndrome)?
27. The right coronary artery (RCA) supplies the atrioventricular (AV) node in approximately 85–90% of individuals (right dominant circulation). The AV nodal artery arises from the RCA at which anatomical landmark?
28. During chest tube insertion in the safe triangle (5th intercostal space, anterior axillary line to midaxillary line), which structure lies at the floor of the safe triangle and marks the inferior limit to avoid diaphragmatic perforation?
29. The coronary sinus opens into which chamber of the heart, and what valve guards its opening?
30. The left recurrent laryngeal nerve loops around which structure in the thorax, explaining why mediastinal pathology (e.g., aortic aneurysm, Ortner syndrome) causes left vocal cord palsy?
31. The right coronary artery (RCA) in most individuals (right dominant) gives rise to the posterior descending artery (PDA). Occlusion of the mid-RCA proximal to the sinoatrial nodal artery would cause infarction of:
32. In cardiac surgery requiring cardiopulmonary bypass, the aortic cannula is placed in the ascending aorta and the venous cannula in the right atrium. The right coronary artery originates from which sinus of Valsalva, and why is this important during aortic root surgery?
33. 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?
34. The fibrous pericardium is firmly attached to the central tendon of the diaphragm. Which structure passes through the central tendon at the T8 level, and what clinical significance does pericardial effusion at the left pleuropericardial angle have?
35. The sinoatrial node lies in the wall of the right atrium near the opening of the superior vena cava. Its arterial supply most commonly arises from:
36. Which thoracic structure lies immediately posterior to the tracheal bifurcation (carina) at the level of the sternal angle (T4–T5)?
37. A surgeon ligates the right coronary artery in its proximal third. Which structure is most at risk for ischemia due to this ligation?
38. The right border of the heart on a PA chest X-ray is formed by which structure at its lower portion?