Motor innervation to the cricothyroid muscle is provided by which nerve branch?

Motor innervation to the cricothyroid muscle is provided by which nerve branch?

• A. Glossopharyngeal nerve
• B. Internal branch of the superior laryngeal nerve
• C. External branch of the superior laryngeal nerve
• D. Recurrent laryngeal nerve

Answer: (C)

Motor control of the cricothyroid muscle is provided by the external branch of the superior laryngeal nerve. This branch carries the motor fibers from the vagus to the cricothyroid, which tilts the thyroid cartilage forward at the cricothyroid joint to tense the vocal cords and raise pitch. The internal branch of the superior laryngeal nerve is sensory to the mucosa above the vocal cords, not motor. The recurrent laryngeal nerve supplies all the other intrinsic laryngeal muscles (and mucosa below the cords) but not the cricothyroid. Glossopharyngeal nerve does not innervate laryngeal muscles.

Motor control of the cricothyroid muscle is provided by the external branch of the superior laryngeal nerve. This branch carries the motor fibers from the vagus to the cricothyroid, which tilts the thyroid cartilage forward at the cricothyroid joint to tense the vocal cords and raise pitch. The internal branch of the superior laryngeal nerve is sensory to the mucosa above the vocal cords, not motor. The recurrent laryngeal nerve supplies all the other intrinsic laryngeal muscles (and mucosa below the cords) but not the cricothyroid. Glossopharyngeal nerve does not innervate laryngeal muscles.