A professional singer undergoes total thyroidectomy for a multinodular goitre. Post-operatively her speaking voice is normal at conversational pitch but she completely loses the ability to sing high notes. Which nerve injury explains this finding?

• A Recurrent laryngeal nerve
• B Internal branch of the superior laryngeal nerve
• C External branch of the superior laryngeal nerve ✓
• D Hypoglossal nerve

Explanation

The external branch of the superior laryngeal nerve runs with the superior thyroid artery and supplies the cricothyroid muscle, the tensor of the vocal cords. Its injury leaves conversational voice intact but abolishes high-pitched phonation, a classic problem in professional voice users. The internal branch is purely sensory to the supraglottic larynx. Unilateral recurrent laryngeal injury causes hoarseness and a weak, breathy voice even at ordinary pitch, which this patient does not have.

Reference: Sabiston Textbook of Surgery, 21st ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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