Which cranial nerve is primarily responsible for swallowing and speech?

The glossopharyngeal nerve is primarily responsible for swallowing and speech due to its crucial role in the motor innervation of the pharynx and its contribution to the sensation of taste in the posterior one-third of the tongue. This nerve helps facilitate the swallowing process by innervating the stylopharyngeus muscle, which elevates the pharynx and aids in the swallowing action. Additionally, it provides sensory input that is important for the gag reflex and the coordination of swallowing.

Moreover, the glossopharyngeal nerve also plays a role in the function of the parotid salivary gland, which can be important during the speech for lubrication and the production of saliva. The overall integration of motor and sensory components by this nerve supports effective communication and swallowing, making it essential in these functions.