Final answer:
The ninth cranial nerve, known as the Glossopharyngeal Nerve, carries sensory and motor information, including taste sensation from the posterior tongue, somatic sensation in the upper pharynx, blood pressure regulation, and muscle control for swallowing.
Step-by-step explanation:
The ninth cranial nerve is known as the Glossopharyngeal Nerve. It is a mixed nerve that carries both sensory and motor information. The major functions of the Glossopharyngeal Nerve include the sensation of taste from the posterior one-third of the tongue, providing somatic sensation to the upper pharyngeal region, monitoring blood pressure and oxygen content in the blood through the carotid body and sinus, and controlling some muscles used in swallowing. This nerve is important in the cranial nerve exam because it helps assess the sensory and motor functions of the head and neck, particularly those related to taste and swallowing.
The Glossopharyngeal Nerve plays a crucial role in maintaining homeostasis by regulating visceral functions. It also works in conjunction with the Vagus Nerve in the gag reflex. Testing this nerve during a cranial nerve exam can help diagnose underlying neurological conditions affecting its function.