During a thoracotomy, a nerve is seen running vertically on the lateral aspect of the fibrous pericardium before piercing the diaphragm, passing anterior to the root of the lung. Which nerve has been identified?
- A Intercostobrachial nerve
- B Vagus nerve
- C Phrenic nerve ✓
- D Sympathetic chain
Correct answer: C. Phrenic nerve
Explanation
The phrenic nerve (A3, A4, A5) descends on the lateral surface of the fibrous pericardium and passes anterior to the root of the lung before entering the diaphragm. The vagus passes posterior to the lung root, which is the discriminating feature examiners test. The sympathetic chain runs along the heads of the ribs, and the intercostobrachial nerve crosses the axilla, neither lying on the pericardium.
Reference: Gray's Anatomy for Students, 4th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.