During thyroidectomy, a surgeon identifies and preserves the external laryngeal nerve (external branch of superior laryngeal nerve). Inadvertent injury to this nerve would cause which specific clinical deficit?

• A Hoarseness and breathy voice from ipsilateral vocal cord paralysis in the paramedian position
• B Loss of tension in the vocal cord (cricothyroid paralysis), causing lowered vocal pitch and voice fatigue ✓
• C Loss of sensation above the vocal cords and reduced cough reflex
• D Bilateral vocal cord paralysis causing stridor

Explanation

The external laryngeal nerve (ELN), the external branch of the superior laryngeal nerve (from CN X), innervates the cricothyroid muscle — the only intrinsic laryngeal muscle not supplied by the recurrent laryngeal nerve. Cricothyroid is the primary tensor of the vocal cord; its paralysis causes reduced pitch range (especially high notes), voice fatigue, and inability to modulate tension. This is the 'nerve of the opera singer' (Amelita Galli-Curci had ELN injury). The RLN injury causes the characteristic hoarse, breathy voice from medial vocal cord paralysis.

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

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Written and medically reviewed by the StethoPrep medical team.