During total thyroidectomy, the recurrent laryngeal nerve (RLN) is at highest risk of injury near the Berry's ligament. The right RLN has which different anatomical course compared to the left RLN that makes it more unpredictable in this region?

• A The right RLN loops around the aortic arch and runs vertically upward in the tracheoesophageal groove
• B The right RLN loops around the right subclavian artery and approaches the larynx obliquely at a more acute lateral angle compared to the left; it is more variable and may run extralaryngeal (non-recurrent variant in 0.5%) ✓
• C The right RLN does not recur and passes directly from the vagus nerve to the larynx
• D The right RLN is longer and is protected by the right common carotid artery throughout its course

Explanation

The right RLN loops around the right subclavian artery (not the aorta) and ascends to the larynx at a more oblique/lateral angle, often deviating from the tracheoesophageal groove. In approximately 0.5–1% of cases, the right RLN is non-recurrent (when the right subclavian arises aberrantly from the aorta as arteria lusoria); in this variant the nerve passes directly from the vagus to the larynx at a right angle, making it extremely prone to injury. The left RLN loops around the aortic arch and runs more reliably in the left tracheoesophageal groove. Both nerves enter the larynx posterior to the cricothyroid joint near the inferior thyroid artery, where Berry's ligament tethers the thyroid.

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

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Written and medically reviewed by the StethoPrep medical team.