A 62-year-old male smoker presents with hoarseness of 6 weeks duration. Chest radiograph shows a mass in the left upper lobe. The anatomical basis for his hoarseness is:
- A Involvement of the left recurrent laryngeal nerve as it loops around the arch of the aorta beneath the ligamentum arteriosum ✓
- B Compression of the right recurrent laryngeal nerve in the tracheo-oesophageal groove
- C Invasion of the left internal laryngeal nerve at the thyrohyoid membrane
- D Direct invasion of the recurrent laryngeal nerve within the jugular foramen
Correct answer: A. Involvement of the left recurrent laryngeal nerve as it loops around the arch of the aorta beneath the ligamentum arteriosum
Explanation
The left recurrent laryngeal nerve descends into the thorax, loops around the arch of the aorta just posterior to the ligamentum arteriosum, and ascends in the tracheo-oesophageal groove. B left apical or mediastinal lung tumour, or enlarged mediastinal nodes, can compress it there, producing left cord palsy and hoarseness. The right nerve loops around the right subclavian artery and never enters the chest, so thoracic lesions characteristically affect the left side.
Reference: Gray's Anatomy for Students, 4th ed.
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