The recurrent laryngeal nerve (RLN) supplies all intrinsic laryngeal muscles EXCEPT one. Which muscle is the exception, and what nerve supplies it?

• A Posterior cricoarytenoid; internal branch of the superior laryngeal nerve
• B Thyroarytenoid; external branch of the superior laryngeal nerve
• C Cricothyroid; external branch of the superior laryngeal nerve ✓
• D Interarytenoid; internal branch of the superior laryngeal nerve

Explanation

The cricothyroid muscle is the only intrinsic laryngeal muscle NOT supplied by the recurrent laryngeal nerve. It is innervated by the external branch of the superior laryngeal nerve. The cricothyroid acts as a tensor of the vocal cords (elongates and tenses the vocal folds by tilting the cricoid cartilage and pulling the thyroid anteriorly). All other intrinsic muscles — including posterior cricoarytenoid (the only abductor), lateral cricoarytenoid, thyroarytenoid, and interarytenoid — are supplied by the RLN.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

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Written and medically reviewed by the StethoPrep medical team.