The external laryngeal nerve, a branch of the superior laryngeal nerve from CN X, supplies which muscle of the larynx?

• A Posterior cricoarytenoid
• B Lateral cricoarytenoid
• C Thyroarytenoid
• D Cricothyroid ✓

Explanation

The external laryngeal nerve (ELN) is the motor branch of the superior laryngeal nerve that innervates the cricothyroid muscle — the only intrinsic laryngeal muscle NOT supplied by the recurrent laryngeal nerve. Cricothyroid is the tensor of the vocal folds, increasing pitch. ELN injury (occurring in about 1% of thyroidectomies when the superior thyroid vessels are ligated high) causes loss of high-pitched voice (the 'singer's nerve'). All other intrinsic laryngeal muscles are supplied by the RLN.

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

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Written and medically reviewed by the StethoPrep medical team.