The lower half of the brainstem that contains the cardiac, respiratory, vomiting, and vasomotor centers and is associated with autonomic, involuntary functions such as breathing, heart rate, and blood pressure.
The glossopharyngeal nerve consists of five components with distinct functions:
Branchial motor (special visceral efferent): Supplies the stylopharyngeus muscle.
Visceral motor (general visceral efferent): Provides parasympathetic innervation of the parotid gland.
Visceral sensory (general visceral afferent): Carries visceral sensory information from the carotid sinus and body.
General sensory (general somatic afferent): Provides general sensory information from the skin of the external ear, internal surface of the tympanic membrane, upper pharynx, and the posterior 1/3 of the tongue.
Special sensory (special afferent): Provides taste sensation from the posterior 1/3 of the tongue.