Glossopharyngeal Nerve: Origin, Function, Factors Affecting, Prevention

The glossopharyngeal nerve, often known as CN IX, is the ninth cranial nerve. These nerves begin at the brain's base. They are attached to different parts of the mouth and throat, muscles, and organs. Each side has one of these nerves.

Glossopharyngeal nerve termination occurs deep within your neck, near the base of your throat. In addition to its many other use, it helps in swallowing. This nerve is one of the select handful in your body to contain three different types of fibres.

Parasympathetic nerves aid tissues and organs in relaxing when they are not in use.

It allows you to taste, touch, and sense temperature. Sensory: Gives you the ability to feel things.

Origin Of Glossopharyngeal Nerve

The medulla oblongata is where the glossopharyngeal nerve originates. It leaves the skull through the jugular foramen, where the tympanic nerve splits off to provide parasympathetic innervation to the parotid gland.

 The superior and inferior ganglia, which contain the cell bodies of the sensory fibres, are located after the jugular foramen. The nerve then descends the neck, innervating the stylopharyngeus and providing sensation to the carotid sinus and body. 

It divides into its other branches, the lingual, pharyngeal, and tonsillar, and ends in the pharynx between the superior and middle pharyngeal constrictors.

The glossopharyngeal nerve has the following branches:

• The tympanic nerve, also known as the nerve of Jacobson, is a parasympathetic neuron that exits the skull through the foramen ovale and forms synapses in the otic ganglion.
• The stylopharyngeus muscle is motor innervated by the stylopharyngeal nerve.
• The nerve to the carotid sinus interacts with the vagus nerve to transmit signals from the baroreceptors in the carotid sinus and chemoreceptors in the carotid body. As a result, the carotid sinus and carotid body assist regulate blood pressure and monitor blood oxygen and CO2 levels, respectively.
• The pharyngeal plexus, which innervates the pharyngeal muscles, is made up of the pharyngeal branches of the sympathetic and vagus nerves.
• The palatine tonsil receives sensory innervation from tonsillar branches.
• The posterior tongue's mucous membrane, follicular glands, and vallate papillae are all supplied by lingual branches.

Function Of Glossopharyngeal Nerve

The functions of the glossopharyngeal nerve are numerous. Near your throat, the glossopharyngeal nerve has an impact on the following muscles, organs, and bodily functions:

• Carotid Sinus: This recess facilitates the flow of blood from the brain into the carotid artery in the neck. It helps to control the blood pressure.
• Middle Ear: Fluid buildup can be distinguished from fullness by sensory nerve fibres. An ear infection can also cause pain.
• Salivary gland, the parotid After you stop eating, CN IX reduces saliva production.
• The back third of the tongue, or the glossopharyngeal nerve, aids with taste perception.

Your brainstem's lowest region, the medulla oblongata, is where the glossopharyngeal nerve originates. Before entering your throat, it travels via a number of neck structures.

Its route comprises:

• Through a tiny hole in your skull called the jugular foramen.
• Running parallel to your jugular vein as it descends your neck.
• A pointed bone in your skull located below your ear, behind the styloid process.
• Reaching out and touching the stylopharyngeus, which is located close to the throat.
• Going through the hyoglossus muscle. This muscle aids in bringing your tongue down and pulling it backwards in your mouth.

Factors Affecting Glossopharyngeal Nerve

Numerous factors can influence CN IX, some of which may have an effect on quality of life. They comprise:

• Glossopharyngeal neuralgia (GPN): During certain activities including sneezing, eating, swallowing, and others, you may experience intense pains in your throat, back of your tongue, or middle ear. Patient will hestitate to eat as they would be worried about the future attacks which can occur by eating..
• Glossopharyngeal nerve Palsy: An illness or injury that impairs CN IX nerve function. The nerve may lose its function and become partially or completely paralysed. Occasionally, a stroke-related consequence is glossopharyngeal nerve palsy.

Prevention Of Glossopharyngeal Nerve Injuries

Some of the factors that contribute to CN IX illness may not be preventable. Glossopharyngeal neuralgia is one condition that can develop for unknown reasons.

It's crucial to get a skilled surgeon if you require surgery to address a problem close to the CN IX. The best option is a doctor who does a lot of the operations you require.

There are some illnesses that can be avoided, like malignancies of the throat and mouth. The following steps can help you lower your risk:

• If you smoke, give up tobacco consumption.
• Reducing the amount and frequency of your alcohol consumption.
• Receiving the HPV vaccine, or the human papillomavirus vaccine.
• Maintaining a healthy lifestyle that includes a wholesome diet and regular exercise.

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