Question:medium
A singer presents with problem in high pitch. On examination bowing of one side vocal cord. Which of the following muscle is affected?
A singer presents with problem in high pitch. On examination bowing of one side vocal cord. Which of the following muscle is affected?
Show Hint
High pitch needs a taut, lengthened cord. Which intrinsic laryngeal muscle is the tensor (supplied by the external laryngeal nerve)?
Updated On: Jun 22, 2026
- Posterior cricoarytenoid
- Lateral cricoarytenoid
- Cricothyroid
- Thyroarytenoid
Show Solution
The Correct Option is C
Solution and Explanation
Reason from the physiology of pitch. Pitch is set by how tense and how long the vocal folds are: tighter, longer folds vibrate faster and produce a higher note. So a singer who suddenly cannot reach high notes has lost the muscle that TENSES and LENGTHENS the vocal cord.
Which muscle does that? Among the intrinsic laryngeal muscles, the cricothyroid is the dedicated tensor - it rocks the thyroid cartilage forward and downward on the cricoid, which stretches and elongates the vocal fold and thereby raises pitch. It is also unique anatomically: it is the ONLY intrinsic laryngeal muscle supplied by the external branch of the superior laryngeal nerve; every other intrinsic laryngeal muscle is supplied by the recurrent laryngeal nerve.
Explain the bowing sign. If the cricothyroid is weak or paralysed (often from external superior laryngeal nerve injury, e.g. after thyroid surgery), the cord on that side cannot be pulled taut, so it loses its straight tense edge, sags and looks bowed on laryngoscopy. Functionally the patient loses high-frequency phonation and tires easily on sustained singing - exactly this professional singer's complaint.
Quick functional sort of the distractors:
- Posterior cricoarytenoid = the sole ABDUCTOR (opens the glottis for breathing). Its job is airway, not tensing for pitch.
- Lateral cricoarytenoid = ADDUCTOR (closes the glottis). Again, not the tensor.
- Thyroarytenoid / vocalis = relaxes and shortens the cord and acts as a weak adductor and fine-tuner; it is the functional opposite of a high-pitch tensor.
Only the cricothyroid stretches the cord for high pitch, so its dysfunction is the single explanation that accounts for BOTH the bowing seen on examination and the high-pitch difficulty reported.
Answer: C.
Which muscle does that? Among the intrinsic laryngeal muscles, the cricothyroid is the dedicated tensor - it rocks the thyroid cartilage forward and downward on the cricoid, which stretches and elongates the vocal fold and thereby raises pitch. It is also unique anatomically: it is the ONLY intrinsic laryngeal muscle supplied by the external branch of the superior laryngeal nerve; every other intrinsic laryngeal muscle is supplied by the recurrent laryngeal nerve.
Explain the bowing sign. If the cricothyroid is weak or paralysed (often from external superior laryngeal nerve injury, e.g. after thyroid surgery), the cord on that side cannot be pulled taut, so it loses its straight tense edge, sags and looks bowed on laryngoscopy. Functionally the patient loses high-frequency phonation and tires easily on sustained singing - exactly this professional singer's complaint.
Quick functional sort of the distractors:
- Posterior cricoarytenoid = the sole ABDUCTOR (opens the glottis for breathing). Its job is airway, not tensing for pitch.
- Lateral cricoarytenoid = ADDUCTOR (closes the glottis). Again, not the tensor.
- Thyroarytenoid / vocalis = relaxes and shortens the cord and acts as a weak adductor and fine-tuner; it is the functional opposite of a high-pitch tensor.
Only the cricothyroid stretches the cord for high pitch, so its dysfunction is the single explanation that accounts for BOTH the bowing seen on examination and the high-pitch difficulty reported.
Answer: C.
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