Which nerve supplies motor innervation to most intrinsic laryngeal muscles (except the cricothyroid)?

Which nerve supplies motor innervation to most intrinsic laryngeal muscles (except the cricothyroid)?

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

Answer: (C)

The essential idea is how motor control is distributed among the nerves that reach the larynx. Most intrinsic muscles of the larynx—those that move the vocal folds and control their tension except for one—get their motor supply from the recurrent laryngeal nerve. This nerve, a branch of the vagus, travels up in the groove between the trachea and esophagus to the larynx and innervates the main vocal fold–moving muscles: the interarytenoids, posterior and lateral cricoarytenoids, thyroarytenoid, and the vocalis portion of the thyroarytenoid. The cricothyroid muscle is the exception in this group; it is responsible for tilting the thyroid cartilage forward to tense the vocal cords and adjust pitch, and its motor supply comes from the external branch of the superior laryngeal nerve, another branch of the vagus. The internal branch of the superior laryngeal nerve mainly provides sensory innervation to the laryngeal mucosa above the vocal cords, not motor. So, the nerve that supplies motor innervation to most intrinsic laryngeal muscles (excluding the cricothyroid) is the recurrent laryngeal nerve.

The essential idea is how motor control is distributed among the nerves that reach the larynx. Most intrinsic muscles of the larynx—those that move the vocal folds and control their tension except for one—get their motor supply from the recurrent laryngeal nerve. This nerve, a branch of the vagus, travels up in the groove between the trachea and esophagus to the larynx and innervates the main vocal fold–moving muscles: the interarytenoids, posterior and lateral cricoarytenoids, thyroarytenoid, and the vocalis portion of the thyroarytenoid. The cricothyroid muscle is the exception in this group; it is responsible for tilting the thyroid cartilage forward to tense the vocal cords and adjust pitch, and its motor supply comes from the external branch of the superior laryngeal nerve, another branch of the vagus. The internal branch of the superior laryngeal nerve mainly provides sensory innervation to the laryngeal mucosa above the vocal cords, not motor.

So, the nerve that supplies motor innervation to most intrinsic laryngeal muscles (excluding the cricothyroid) is the recurrent laryngeal nerve.