Left vocal fold paralysis due to the left recurrent laryngeal nerve looping around which structure?

• A. Aortic arch
• B. Subclavian artery
• C. Pulmonary trunk
• D. Carotid sheath

Answer: (A)

The left recurrent laryngeal nerve has a distinctive thoracic course: it loops under a vascular structure before it ascends to the larynx. Specifically, it hooks beneath the aortic arch (near the ligamentum arteriosum) in the superior mediastinum, then travels up between the trachea and esophagus to innervate the intrinsic muscles of the left vocal cord. This looping around the aortic arch makes the left vocal fold susceptible to paralysis if the arch or surrounding mediastinal structures are diseased or injured. In contrast, the right recurrent laryngeal nerve loops around the right subclavian artery, not the left, and the pulmonary trunk or carotid sheath aren’t the structures it wraps around on the left.