When referring to the vagus nerve, it is common for us to wonder why it has received its name. Well, to understand it we have to refer to its origin from Latin vagus, which could be translated as itinerant or wandering. This is tied to its flashy extension and not to the fact that it commands some autonomous functions, as is sometimes assumed.
While is true that part of respiration and digestion is due to the action of this cranial nerve and its neurotransmitters, its importance is not limited thereto. It is an anatomical component with a motor and sensory capacity that, if damaged, causes severe problems.
What is the vagus nerve like?
The vagus nerve is the tenth cranial nerve. These pairs are groups of neurons that are born in the brain, on both sides of the body's midline, and serve different functions. There are twelve pairs in total, some limited to the head and others with extensions on the outside.
To exit the skull, the vagus nerve runs through a neurovascular bundle that is located in the neck and is usually called by the name of carotid. These bundles are groups of arteries, veins and nerves that share an anatomical path to travel to their places of action.
In this case that we analyze, the carotid arteries and jugular veins travel in parallel on each side of the neck, adding to them this tenth cranial pair. When they penetrate the thorax, the paths become somewhat different on each side. For its part, the right vagus is placed behind the structures that connect the lungs with the trachea. On the left side it goes through the front.
As it progresses, it provides nerve branches that contribute to the formation of plexuses within the chest. One of these is the esophageal, as well as the cardiac and pulmonary. Finally, they cross into the abdomen through the esophageal hiatus, a hole in the diaphragm through which the esophagus runs.
The conclusion of its anatomy is different depending on the side that is analyzed. The right vagus joins the solar plexus and, one might say, innervates abdominal organs. On the other side, the left one fuses its branches with the stomach.
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Fibers that compose it
As we well said, the vagus nerve is sensitive and motor. So, the fibers that compose it in its privacy are multiple and are divided based on its primary functions:
Sensitive for the viscera: They are those that reach the pharynx, the heart and the lungs. A part of them are also related to the sense of taste and touch the epiglottis, in the upper part of the larynx.
Sensitive otic: they target the ear canal and the eardrum in a timely manner.
Parasympathetic: responsible for impulses that come from the autonomic nervous system, so they play roles in the heart and the digestive tract, transmitting autonomous information.
Motorboats: They are for the muscles of the pharynx and larynx.
Functions of the vagus nerve
We could say, emphasizing that it is a mixed, motor and sensitive nerve, that its functions are better understood if we respect that grouping. Some fibers will regulate movements, while others will transmit sensitive information to the brain.
The throat, part of the ear, the skin behind the ear, the back of the tongue and almost all the organs that we have mentioned so far take advantage of the 10th cranial nerve to send sensory information. In the same way, as we anticipated, taste has a specific participation of the nerve.
Regarding motor functions, these neurons apply their role in many involuntary actions of organs like the heart, esophagus, and larynx. Peristalsis, for example, which is the movement by which the digestive system drives the bolus, involves vague fibers.
Vagus nerve problems
On its long journey through the human body, the vagus nerve can be injured. Many of them stem from accidents or trauma that affect you at some point in your anatomical wandering. According to the height of the affectation are the symptoms.
Similarly, the location determines the organs that suffer from it. Two are the most frequent situations: neuronal damage and gastroparesis. Let's take a closer look at each one.
Damage to the vagus nerve
Surgery may damage the vagus nerve by inadvertent medical error. It can also happen that a car accident causes a fracture that damages you. Tumors, benign or malignant, run with the possibility of putting extreme pressure on it and affecting its functioning.
The area where the problem is evident will lead to signs and symptoms, sometimes distant, since they will be expressed in the organs where the nerve branches are deposited at the end of their journey. We could face disorders of the larynx, esophagus, heart and digestive system.
There are patients who become dysphonic or hoarse, others who see their heart rate altered. Also vomiting and nausea are a possibility. In the esophagus the act of swallowing stops, with difficulty in swallowing liquids or solids.
Gastroparesis is, in basic terms, the slowness of the stomach to specify its stage of digestion. For this reason, food remains too long inside the organ and may even tend to flow back to the outside in the form of reflux or vomiting.
It is known that the origin of the disorder is a failure in the nerve connection between the brain and the digestive tract; This is why the vagus nerve always appears as the first-hand culprit. However, there are other nerves that could lead to gastroparesis. There are even more than a third of the cases that are considered without proven etiology.
What would alter the function of the tenth cranial nerve is very varied. Surgical damage must be considered, up to virus infections that settle in these neurons and diabetes. Also autoimmune diseases can concentrate their attack on the myelin of the vagus nerve.
People with gastroparesis have abdominal pain, nausea, and vomiting. If it is prolonged in time, there is malnutrition because the patient stops eating correctly, in addition to not being able to assimilate the nutrients in the way they should.
Treatments combine prokinetic drugs, such as metoclopramide, with surgery or newer approaches. Here we can include the stimulation of the vagus nerve.
Vagus nerve stimulation
As its name suggests, vagus nerve stimulation consists of imparting electrical waves from a device designed for this purpose, so that they reach the neurons in question. This would cause a signal to the brain that would be returned all the way from the innervated organs to modify troubled function.
The technique is indicated for epilepsy, multiple sclerosis and migraine. It has also been experienced in cases of severe depression and Alzheimer's disease. Since the implanted device requires surgery and has some side effects, the approach is reserved for cases where conventional treatments fail.
Discover more: Vagus nerve stimulation in the ear
A cranial nerve beyond the skull
The tenth cranial nerve or vagus nerve is important in the head, chest and abdomen. His anatomical and physiological knowledge allowed him to move towards treatment modalities such as stimulation that were unthinkable decades ago.
When there are digestive or autonomic nervous system symptoms that cannot be diagnosed in the first instance, it is always a possibility that this nerve is causing problems. Health professionals will be the ones to investigate, through complementary methods, the origin of the disorders.
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