Advanced Dental Admission Test (ADAT)

What is the motor function of the external laryngeal nerve?

1. Innervates the vocal folds

2. Motor to the cricothyroid muscle

3. Sensory to laryngeal mucosa

4. Controls swallowing

The correct answer is: Motor to the cricothyroid muscle

The external laryngeal nerve is primarily responsible for providing motor innervation to the cricothyroid muscle, which plays a crucial role in modulating pitch by tensing the vocal cords. When this muscle contracts, it elongates and raises the tension of the vocal folds, resulting in a higher pitch of sound. This function is essential for proper phonation and voice modulation. In contrast, other options discuss functions that are either unrelated to the external laryngeal nerve or are associated with different structures. For example, innervation of the vocal folds is primarily managed by the recurrent laryngeal nerve, while sensory innervation and control of swallowing involve different branches of the vagus nerve. Understanding the specific roles of these nerves is important for recognizing how motor functions in the larynx are distributed among different components of the nervous system.