A surgeon performing total thyroidectomy injures the external branch of the superior laryngeal nerve on the right. Which deficit is expected postoperatively?
- A Loss of cricothyroid function causing easy fatigability of voice and loss of high pitch ✓
- B Hoarse, breathy voice with an immobile vocal cord in the cadaveric position
- C Complete anaesthesia of the laryngeal inlet above the vocal cords
- D Aspiration due to loss of sensation below the vocal cords
Correct answer: A. Loss of cricothyroid function causing easy fatigability of voice and loss of high pitch
Explanation
The external branch of the superior laryngeal nerve runs with the superior thyroid artery and supplies cricothyroid, the tensor of the vocal cord. Its injury leaves the voice weak and unable to reach high pitches, classically noted in professional singers after thyroid surgery. Option B describes recurrent laryngeal nerve injury, the more feared complication. Internal laryngeal nerve injury causes sensory loss ABOVE the cords, not below, making option D wrong on both nerve and territory.
Reference: Gray's Anatomy for Students, 4th ed.
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