Vagus Nerve

The peripheral nervous system (PNS) of the animal body has two parts- the somatic nervous system and the autonomic nervous system. The autonomic nervous system controls the function of the internal organs of the animal body. The ANS completes its operation through the sympathetic nervous system and the parasympathetic nervous system. The parasympathetic nervous system regulates body functions. The vagus nerve is one of the most important components of the parasympathetic nervous system. It is the longest pair of the 12 pairs of cranial nerves. It consists of the left and right vagus nerves. It connects the brain with the gastrointestinal tract. It sends information to the brain about the states of the internal organs through different fibers. The vagus nerve affects heart rate, digestion, immune response, mood, etc. In this article, we will discuss vagus nerve function, vagus nerve anatomy, vagus nerve pathway, vagus nerve disorders, vagus nerve stimulation in detail.

Anatomy Of Vagus Nerve

The vagus nerve is the longest cranial nerve of the parasympathetic nervous system. It is structured with a pair of nerves- the left vagus nerve and the right vagus nerve. This nerve runs from the brain to the colon. It is also called the ‘wanderer nerve’ for its long extension in the animal body. It carries a massive range of signals from the brain to the internal organs and the digestive system and vice versa. This nerve exits the cranium via the jugular foramen originating from the medulla of the brainstem. It passes into the carotid sheath in the neck. The nerve is divided into the left and right parts at the base of the neck. Two parts of the nerve have different vagus nerve pathways from the neck. The right path creates the posterior vagal trunk and the left part forms the anterior vagal trunk in the thorax. Both the vagal trunks end in the abdomen. You can go through the vagus nerve anatomy PDF to learn the diagram.

Vagus Nerve Function

The vagus nerve plays a vital role in the autonomic nervous system. It has several different functions in the animal body. The vagus nerve affects some important internal body processes such as heart rate, digestive system, immune response, mood, etc. The main four functions of this nerve are sensory, special sensory, motor, and parasympathetic. The sensory functions operate on the throat, heart, lungs, and abdomen. The special sensory function provides taste sensations behind the tongue. The motor functions provide movement functions for the muscles in the neck. The parasympathetic functions are responsible for the respiration and digestive tract. Some other functions are communication between the brain and the gut, relaxation with deep breathing, lowering blood pressure, decreasing inflammation, fear management, etc. Apart from these, the vagus nerve function in the heart is also crucial for the animal body.

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Vagus Nerve Location

As the Vagus nerve is the longest of all cranial nerves, it is connected from the brain to the bottom part of the body. The Vagus nerve location can be explained systematically. The vagus starts from the brain and moves towards the face and reaches the abdomen through the thorax. The Vagus nerve is quite a complex nerve that has parasympathetic fibers as well as two branches of sensory ganglia.

One is superior sensory ganglion which moves through the skin and reaches the ear's concha. Again, the inferior vagus nerve ganglion is divided into two branches. The pharyngeal nerve and the laryngeal nerve along with esophageal, and pulmonary branches. Each branch functions for different parts of our bodies. These nerves send signals to all parts of the body which include the stomach,  cardiac muscles, pancreas, etc.

Functions of Vagus Nerve

The vagus nerve is the 10th cranial nerve in the body and has different types of functions. They are as follows. 

Sensory Functions:- 

The sensory functions of the vagus are divided into two different components.

• One is somatic components which refer to the sensations felt by the brain from the skin as well as muscles.

• If the sensations felt by the brain are due to the organs of the body, then those components are known as visceral components.

Besides these components, the sensory functions performed by the Vagus nerve are as follows- 

• They help to provide the information from the brain to the skin, middle parts of the throat, and external parts of the ear.

• The larynx, heart, esophagus, trachea, lungs, and most of the digestive tract receive visceral information through the brain.

• Also contributes to providing the information of taste at the bottom part of the tongue. This part is also known as the root part of the tongue. This function is nothing but a special sensory function of the Vagus nerve.

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Motor Functions

The motor functions of the Vagus nerves majorly include the transferring of information for the larynx and pharynx. 

• Provides information and stimulates a muscle of the fleshy part around the tongue and mouth. These parts include the larynx, firings, and a soft palate.

• It also has a major part in reducing the resting heart rate.

• A motor function that helps to contract the involuntary muscles of the stomach, intestine and helps to move the food through a tract. 

These are the different functions performed by the vagus nerve present in the body. Also, some cardiac functions were known as parasympathetic functions of the Vagus nerve. The vagus nerves supply all types of information to various parts of the body. Every function of the vagus nerves has its cell bodies, unique name, etc. 

Bottom Line 

Hence, the vagus nerve helps to supply various information to various parts of the brain and vice versa. This is the 10th cranial nerve present in the body. The Roman number is used to represent its notation. One should keep all the cranial nerves properly and healthy. Especially the vagus should be healthy as it performs various functions.

Vagus Nerve Disorders

There are several damages of the vagus nerve that are noticeable in the animal body. The potential symptoms of vagus nerve damage are difficulty in speaking, change of voice, loss of the gag reflex, difficulty swallowing, slow heart rate, low blood pressure, nausea or vomiting, changes in the digestive process, abdominal pain, depression and anxiety, heart diseases, etc. Two common vagus nerve disorders are gastroparesis and vasovagal syncope. The symptoms of gastroparesis are nausea or vomiting, acid reflux, loss of appetite, abdominal pain, fluctuations in blood sugar and blood pressure, unexplained weight loss, etc. The symptoms of vasovagal syncope are warmth, tunnel vision, nausea, low blood pressure, slow or irregular heartbeat ringing in the ears, excessive sweating, etc. 

Vagus Nerve Stimulation

The treatment process of vagus nerve diseases is called vagus nerve stimulation. It is a medical process that is done manually or through electrical pulses. Generally, it is used for the treatment of mental illness and epilepsy. The simulation process is used in some specific mental conditions such as bipolar disorder, Alzheimer’s disease, anxiety disorders, etc. For epilepsy, a small electrical device is used for stimulation. A thin wire from the device is connected to the vagus nerve in this process. The side effects of this treatment process are hoarseness or changes in voice, shortness of breath, sore throat, coughing, difficulty in swallowing, slow heart rate, stomach discomfort or nausea, etc.