A 65-year-old man undergoes left total thyroid lobectomy. Intraoperatively, the surgeon identifies the recurrent laryngeal nerve (RLN) just before the nerve enters the larynx. A small branch of the inferior thyroid artery is noted crossing the nerve from the medial side. The variant nerve relationship described is most associated with:

• A Extra-laryngeal branching of RLN ✓
• B Non-recurrent laryngeal nerve (NRLN)
• C Normal anatomy — RLN always crosses posterior to inferior thyroid artery
• D Zuckerkandl's tubercle compressing the nerve

Explanation

The recurrent laryngeal nerve may branch before entering the larynx (extra-laryngeal branching), occurring in 20-30% of cases. The anterior branch carries motor fibers to the intrinsic laryngeal muscles; the posterior branch carries sensory and motor fibers. Failure to identify branching can result in inadvertent division of one branch. The RLN typically passes posterior to or between branches of the inferior thyroid artery (variable relationship). Non-recurrent laryngeal nerve (right-sided, associated with aberrant right subclavian artery) runs horizontally and is a distinct variant. Zuckerkandl's tubercle is a posterior thyroid projection that can displace the RLN laterally.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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Written and medically reviewed by the StethoPrep medical team.