In this lesson, you’ll learn about the glossopharyngeal nerve. The lesson includes information on the location and function of the nerve, symptoms that indicate if the nerve is damaged, and ways the nerve can be tested to make sure it’s working properly.
Location and Function of the Nerve
Do you know what your throat, salivary glands, sinuses, and middle ear have in common? The glossopharyngeal nerve, also known as cranial nerve pair number 9 (out of 12 pairs), coordinates information for all of these body parts. Originating in the medulla oblongata in the brain stem, this is a mixed nerve in that it has both sensory and motor functions.Below is a diagram showing the location of the branches of the glossopharyngeal nerve:
The sensory division of the glossopharyngeal nerve receives information from:
- The pharynx (part of the throat)
- The posterior third of the tongue
- The parotid salivary gland
- The middle ear
The motor division sends information to the:
- Parotid gland
- Muscles in the throat
- Nerve bundles (plexus) in the throat
The glossopharyngeal nerve’s main functions are initiating swallowing and the gag reflex, but it has other functions as well. These are broken into the five pathways the nerve has outside of the brain.
- The special sensory branch provides taste sensation form the taste buds located in the posterior third of the tongue.
- The visceral sensory branch carries information from the sinuses in the face.
- The general sensory branch brings information from the skin on the external ear, the tympanic membrane in the ear, the pharynx and the posterior third of the tongue.
- The visceral motor branch sends parasympathetic signals to the parotid glands.
- The branchial motor branch sends information to the stylopharyngeus muscle in the throat to facilitate swallowing.
Damage to the Glossopharyngeal Nerve
Damage to the glossopharyngeal nerve can occur as a result of a stroke, and tumors or small cysts at the base of the skull also can put pressure on the nerve. Symptoms of damage vary depending on which branch of the nerve is affected.
The most common sensory symptom is a loss of bitter and sour taste from the posterior third of the tongue, while the most common motor symptom is trouble swallowing.
Testing for Damage to the Nerve
The glossopharyngeal nerve can be tested by checking a person’s gag reflex and also doing a taste test on the posterior third of the tongue to see if he or she can sense bitter and sour flavors. There is no easy way to test the other branches of the nerve for integrity since they correspond with the functions of some other cranial nerves, thus making it difficult to determine if the damage is from the glossopharyngeal nerve or one of these other cranial nerves.
The glossopharyngeal nerve is a mixed cranial nerve originating in the medulla oblongata.
It has a sensory division, which receives information from the ear, tonsils, pharynx, carotid sinus, and tongue. The motor division sends information to the parotid gland and also controls the muscles in the pharynx that aid in swallowing. Damage to the nerve can result in a loss of taste, particularly bitter and sour flavors, and trouble swallowing. The nerve can be tested by checking a person’s gag reflex and doing a taste test on the posterior third of the tongue.Medical Disclaimer: The information on this site is for your information only and is not a substitute for professional medical advice.