Isolated unilateral vocal cord paralysis is encountered far more frequently on the left than on the right. What anatomical fact explains this difference?

• A The right recurrent laryngeal nerve runs inside the carotid sheath
• B The left superior laryngeal nerve supplies both cricothyroid muscles
• C The left recurrent laryngeal nerve loops around the arch of the aorta and has a longer intrathoracic course ✓
• D The left recurrent laryngeal nerve passes through the thyrohyoid membrane

Explanation

On the left, the recurrent laryngeal nerve hooks around the aortic arch distal to the ligamentum arteriosum and ascends in the tracheo-oesophageal groove, giving it a long thoracic course exposed to apical lung tumours, mediastinal nodes and aortic pathology. On the right it loops under the subclavian artery, a much shorter course, so right-sided isolated palsy should prompt a search for a lesion near the thoracic inlet.

Reference: Gray's Anatomy, 42nd ed.

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Written and medically reviewed by the StethoPrep medical team.