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?

• A Left subclavian artery
• B Left pulmonary artery
• C Arch of the aorta at the level of the ductus arteriosus (ligamentum arteriosum) ✓
• D Superior vena cava

Explanation

The left recurrent laryngeal nerve branches from the left vagus at the level of the aortic arch, loops under the arch at the site of the ductus arteriosus/ligamentum arteriosum just lateral to the tracheoesophageal groove, then ascends in the groove to reach the larynx. Any structure that enlarges the aortic arch — aneurysm, enlarged subcarinal lymph nodes, left hilar malignancy — can compress the nerve, causing left vocal cord palsy and hoarseness (Ortner's cardiovocal syndrome). The right recurrent laryngeal nerve loops around the right subclavian artery at a higher, cervical level.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.