Which cranial nerve is involved in phonation?

The vagus nerve, also known as cranial nerve X, plays a crucial role in phonation because it innervates the majority of the muscles involved in voice production. This nerve is responsible for supplying the intrinsic laryngeal muscles, which are essential for the modulation of sound and pitch during speaking. The vagus nerve manages the position and tension of the vocal folds, enabling them to vibrate as air passes through, which is fundamental in generating vocal sounds.

Additionally, the vagus nerve has branches that provide sensory innervation to the larynx, contributing to the cough reflex and providing feedback necessary for voice modulation. The phonatory function is vital in communication, making the vagus nerve's role in this process particularly significant. Thus, its involvement in controlling laryngeal dynamics makes it the correct answer for the cranial nerve responsible for phonation.