Cranial Nerve IX, also known as the glossopharyngeal nerve, is a mixed nerve that plays a crucial role in both sensory and motor functions. It is responsible for transmitting taste sensations from the posterior one-third of the tongue and providing sensory input from the throat and tonsils. Additionally, it helps regulate blood pressure and oxygen levels through its connections to the carotid body and carotid sinus. In terms of motor function, Cranial Nerve IX innervates the stylopharyngeus muscle, which assists in swallowing. It also contributes to the gag reflex and is involved in the secretion of saliva from the parotid gland. Overall, this nerve is essential for various functions related to taste, swallowing, and autonomic regulation.