Vagus nerve
Synonyms in a broader sense
Vagus nerve, 10th cranial nerve, nerve, nervous system, nerve cell, CNS, parasympathetic nerve
English: vagus nerve
introduction
The vagus nerve is that 10. Cranial nerve (X) and is clearly different from the other 11 cranial nerves. Translated from Latin, his name means something like "The wandering nerve". Rightly so, because it does not - like the other cranial nerves - primarily serve to supply the head area, but it supplies almost all organs of the body parasympathetically (see also: Parasympathetic nervous system).
That is why it is the largest nerve in the parasympathetic system. But it is not only under the thumb of the parasympathetic nervous system, it also supplies muscles (e.g. those of the larynx) and serves for sensitive perception in certain areas (e.g. throat and larynx). It also conveys part of our sense of taste.
The parasympathetic fibers of the vagus nerve arise in the nucleus of the cranial nerve with the name Nucleus dorsalis nervi vagi and then pull as different small branches to the different recipient organs.
Read more on the subject: Cranial nerves
Course of the vagus nerve
The vagus nerve has the longest course within the 12 cranial nerves of humans, because although it originates in the brain, it extends along the digestive system down to the deep abdominal regions. Its origin lies in several different cranial nerve nuclei in the elongated spinal cord, which are responsible for the different qualities of the nerve. As soon as it leaves the elongated spinal cord, which is the lowest area of the brain and merges into the spinal cord, it exits through a small hole in the base of the skull. It then runs together with the carotid artery (Common carotid artery) and the great jugular vein (Internal jugular vein) in a connective tissue sheath (Carotid vagina) down along the neck and enters the chest cavity. There the nerve runs more towards the rear and in close proximity to the heart, lungs and esophagus. It attaches itself directly to the esophagus and accompanies it through the diaphragm into the abdominal cavity, which is its final destination. The nerve divides into many branches and supplies the digestive organs and kidneys. It should be noted that throughout its entire course from the brain to the abdominal region, smaller nerve branches arise from the vagus, which supply the nearby organs.
Read more on the subject: Parasympathetic tasks
Function of the vagus nerve
As already mentioned, the vagus supplies a large number of organs from head to stomach. Its function is very specific, depending on which organ is being considered. It represents the most important representative of the "parasympathetic nervous system". This works in the opposite direction to the "sympathetic nervous system". Roughly speaking, the parasympathetic system is responsible for rest, relaxation and digestion, while the sympathetic system is evolutionarily responsible for fighting and flight situations.
In the head / neck area, the vagus nerve is responsible for the sensitive and sometimes gustatory sensation of the pharynx, the larynx, the glottis, areas of the meninges and parts of the auditory canal. It also activates the muscles of the throat and especially those of the larynx and glottis and thus enables both speaking and swallowing. In the chest cavity, the vagus nerve primarily has calming effects on the lungs and heart. One of its most important effects affects the digestive system. It has digestive effects on the esophagus, stomach, liver, gall bladder, pancreas, small intestine and parts of the large intestine.
Read more on the subject: Trigeminal nerve
Recipient organs of the vagus nerve
The recipient organs of the vagus nerve are located in the chest and abdomen. For example, it supplies the liver, kidneys, spleen and stomach.
The point at which the parasympathetic supply from the vagus nerve ends is called "Cannon-Boehm point". It is located in the middle section of the large intestine (more precisely: the last third of the Transverse colon).
While the cranial part of the parasympathetic nervous system innervates the lacrimal and salivary glands as well as some of the eye muscles and all organs of the chest and abdomen up to the Cannon-Böhm point, the sacral part of the parasympathetic nervous system starts at that point and continues the supply downwards away. So it innervates the rest of the colon, the urinary bladder and the genitals.
Here, too, for those interested in details, a precise description of the facts:
The sacred part of the parasympathetic arises in the Nucleus intermediolateralis and Nucleus intermediomedialis of the sacral part of the spinal cord (Sacral marrow) and then runs with the Pudendal nerve. It then goes through the Inferior hypogastric plexus (lat. Plexus = Nerve plexus). Switching to the 2nd neuron takes place either here or directly in the wall of the receiving organ. From this plexus the parasympathetic fibers run as Nervi pelvici (Latin pelvis = pelvis, i.e. pelvic nerves) to the organs on which they work.
Function in the abdominal area
The vagus nerve supplies the following organs within the abdominal region: stomach, liver, gall bladder, pancreas, kidneys, small intestine and parts of the large intestine. Apart from the kidneys, these are digestive organs. A parasympathetic effect primarily promotes bowel movements and the secretion of the organs. In the process, digestive secretions are formed and released which, in conjunction with the movement of the intestines, enable the food to be crushed, moved and digested.
What influence does the vagus nerve have on the function of the heart?
The vagus nerve or the parasympathetic nerve has a dampening effect on the heart. However, it only affects the atrium of the heart, which is responsible for the frequency, and can therefore only control the heartbeat (Pulse) slow down and not directly the impact force (Blood pressure) reduce. However, this effect arises anyway, since the parasympathetic and sympathetic nerves influence and inhibit each other as opponents. The parasympathetic nervous system inhibits the strengthening function of the sympathetic nervous system in the heart.
How can you calm the vagus nerve?
Soothing the vagus is not a very common practice, so there are few suggestions on the matter. In principle, nerves can be paralyzed or destroyed for a while with medication. In the case of the vagus, however, this only makes sense on its terminal branches on certain organs (for example with stomach ulcers) because it regulates too many important functions in the body. Another obstacle is that the vagus nerve runs very deep in the body and gives off very important nerve branches at an early stage, making it difficult to access. The best place to reach the vagus is along the neck during its course, as it is rather superficial there and has not yet broken up much. There are theories that you can calm the nerve at this point by drinking cold water.
Another way to calm the vagus is to use the interplay of the parasympathetic and sympathetic nerves. The more the sympathetic nervous system is active, the less active the parasympathetic nervous system and vice versa. In order to calm the vagus, and thus the parasympathetic, one would have to activate the sympathetic. This nervous system is responsible for “fight and flight situations” and is mainly stimulated in everyday life by stress and during sporting activity.
Read more on the subject: Phrenic nerve
What happens if the vagus nerve is irritated?
In medicine, one usually speaks of "irritation" when there is a provocation or activation of the nerve. This is usually triggered either by mechanical pressure or by electrical stimulation. An irritation of the vagus nerve ("vagus stimulus") describes a nerve reflex that can be triggered by mechanical pressure on the neck and is sometimes used in medicine. An internal reflex arc is used, which is responsible for regulating blood pressure. On the blood vessels of the neck (Carotid artery) there are small "sensory cells" that measure pressure and send signals to the brain. The brain evaluates the pressure conditions and lowers or increases the blood pressure.
One-sided "massage" of the carotid artery simulates increased pressure in the brain, which leads to an immediate drop in blood pressure. This effect can therefore improve the symptoms in patients with critically elevated blood pressure. However, the method is very dangerous because reflexively it can also lead to a fainting attack. This is why it is rarely used nowadays and, if necessary, can only be carried out by a doctor.
What symptoms / complaints can a vagus nerve disorder cause?
In order to answer this question, it must first be clarified what exactly the "malfunction" is. Nerves are very sensitive and therefore easy to irritate. In doing so, however, they can have both a greater activity and a reduced activity. Anyone who has ever bumped their elbow knows that tingling and pain can also be a symptom. Symptoms of a disorder result from decreased or increased activity and can appear in the vagus as follows: nausea, stomach acidity, constipation or diarrhea, irregular or too fast heartbeat, hoarseness, difficulty swallowing, headache, increased sweating, cold hands and feet, constricted pupils and many others More complaints.
Many of these symptoms are very unspecific as they occur in many other diseases. However, if several of these symptoms occur simultaneously or one after the other, a disorder of the vagus nerve should definitely be considered and clarified by a family doctor.
Inflammation / irritation of the vagus nerve
Symptoms of nerve inflammation are mainly pain, numbness, muscle twitching and loss of function of the nerves. However, since the vagus hardly innervates skin and muscles, numbness and muscle twitching are rare. Inflammation is therefore noticeable primarily through pain and loss of function. The location of the inflammation can be narrowed down based on the symptoms, but it remains difficult to diagnose. The most vulnerable part of the vagus is in the throat and affects the upper laryngeal nerve. The main symptoms are hoarseness, pain when swallowing and coughing.
Read more on the subject: Nerve inflammation
Can you pinch the vagus nerve?
The vagus nerve usually runs along soft tissue organs and is therefore very well protected against entrapment. However, there is a point on the neck where this is even common.After the nerve emerges from the base of the skull, it runs along the first cervical vertebra, together with the carotid artery and the large jugular vein. With strong rotation of the neck or chronic misalignment of the vertebra, compression of these ducts can occur (Vagus compression syndrome).
How can you stimulate the vagus nerve?
Vagus nerve stimulation is a recognized therapy for, for example, epilepsy, depression and anxiety disorders. There are various methods of doing this. In an invasive method, a pulse generator is transplanted under the skin. This stimulates the vagus regularly via an electrode. Another non-invasive method is to stimulate the nerve on the auricle through the skin. The excitation is conducted to the brain via the nerve, where it has stimulating effects.
What influence does the vagus nerve have on nausea?
The vagus nerve, together with the 9th cranial nerve, is responsible for triggering and controlling the nausea. Since nausea is the main cause of nausea, there is a direct connection between the vagus nerve and nausea. Stimulating the vagus can lead to nausea and vomiting. In addition, the vagus promotes the production of gastric juice. This is very acidic and with increased production also leads to nausea and abdominal pain.
What influence does the vagus nerve have in arrhythmias?
As already mentioned, the vagus nerve has a dampening effect on the heart rate. If the heart rate is manipulated, especially if these have very sudden effects, there is always the risk of an arrhythmia. The parasympathetic nervous system extends the conduction time within the heart between the atrium and the ventricle and thereby slows down the frequency. However, it can happen that the transition took too long and the ventricle has already made itself independent and works in an irregular rhythm.
Read more on the subject: Cardiac arrhythmia
