**4.2 Brain functions in swallowing**

The sensory nerves report perceptions of pressure, texture, taste, and temperature, and these are transmitted by these afferent nerves to the brain. The primary source of these stimuli is from the nerves in the lips and then, in turn, the tongue, soft palate, and pharynx (**Figure 6)** [5, 29]. The (CN V) Trigeminus is the thickest and fastest of the efferent nerves, and thus the signals from the lips are the first to reach the brain stem. It is therefore a mistake to concentrate on therapies for the tongue, soft palate, and pharynx that omit the importance of the lips.

The five cranial motor nerves that are important for swallowing are CN V Trigeminus, CN VII Facialis, CN IX Glossopharyngeus, CN X, Vagus, and CN XII Hypoglossus*.* The first four are both sensory (afferent), and motor (efferent) nerve pathways; which send information both to and from the brain - the sensory-motoric reflex arc.

**Figure 6.** *The cranial nerves and reflex points of the oral cavity.*
