Vagus nerve, 10th cranial nerve, nerve, nervous system, nerve cell, CNS, parasympathetic
English: vagus nerve
The Nervus vagus is the 10th cranial nerve (X) and differs clearly from the other 11 cranial nerves. His name translates from Latin as "the wandering nerve". Rightly so, because he does not serve - like the other cranial nerves - primarily the supply in the head area, but he supplies almost all organs of the body parasympathisch ( see also : parasympathetic).
That is why he is the greatest nerve of the parasympathetic system. But he is not only under the thumb of the parasympathetic nervous system, but also supplies muscles (eg those of the larynx) and serves the sensitive perception in certain areas (eg throat and larynx). It also conveys part of our taste sensation.
The parasympathetic fibers of the vagus nerve arise in the cranial nerve nucleus with the name dorsal nerve nerve vagi and then pull as different small branches to the various recipient organs.
The vagus nerve has the longest course within the 12 cranial nerves since it originates in the brain, but extends along the digestive system into deep abdominal regions. Its origin lies in several different cranial nerve nuclei in the extended 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 part of the brain and goes into the spinal cord, it emerges through a small hole in the base of the skull. It then runs down along the neck along with the carotid artery and the great jugular vein ( internal jugular vein ) in a connective tissue sheath ( vagina carotica ) and enters the thoracic cavity. There, the nerve runs more in the back area and in close proximity to the heart, lungs and esophagus. He attaches himself directly to the esophagus and accompanies it through the diaphragm into the abdominal cavity, which is his final destination. The nerve divides into many branches and supplies the digestive organs and kidneys. It should be noted that during the entire course from the brain to the abdominal region, the vagus constantly grows smaller nerve branches, which supply the respective nearby organs.
As already mentioned, the vagus supplies many organs from head to belly. Its function is very specific, depending on which organ is considered. It represents the most important representative of the "Parasympathischen nervous system". This counteracts the "sympathetic nervous system". Roughly speaking, the parasympathetic system is responsible for rest, relaxation and digestion, while the sympathetic system is historically responsible for combat and refugee institutions.
In the head / neck area, the vagus nerve is responsible for the sensitive and partly sensory sensation of the pharyngeal mucosa, larynx, glottis, areas of the meninges and parts of the auditory canal. It also activates the muscles of the pharynx and especially those of the larynx and glottis, thus enabling both speech and swallowing. In the chest cavity, the vagus nerve has calming effects on the lungs and the heart. One of its most important effects concerns the digestive system. It has digestive effects on the esophagus, stomach, liver, gall bladder, pancreas, small intestine and parts of the colon.
The recipient organs of the vagus nerve lie 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-Böhm point ". It lies in the middle section of the large intestine (more precisely: last third of the transverse colon ).
While the cranial portion of the parasympathetic nervous system innervates tears and salivary glands as well as some of the eye muscles and all organs of the thoracic and abdominal cavity up to the Cannon-Böhm point, the sacral part of the parasympathetic nervous system starts at that point and continues to supply it below continued. It innervates the rest of the colon, the bladder and the genitals.
Again, for the detail-interested again a precise naming of the facts:
The sacral part of the parasympathetic nerve originates in the intermediolateral nucleus and intermediomedial nucleus of the sacral part of the spinal cord ( sacral marrow ) and then runs once with the pudendal nerve . He then goes through the hypogastric plexus inferior (lat. Plexus = Nervengeflecht). Switching to the 2nd neuron happens either here or only directly in the wall of the recipient organ. From this plexus, the parasympathetic fibers run as Nervi pelvici (Latin pelvis = pelvis, ie pelvic nerves) to the organs in which they act.
The vagus nerve supplies within the abdominal region the following organs: stomach, liver, gall bladder, pancreas, kidneys, small intestine and parts of the colon. Apart from the kidneys, these are digestive organs. A parasympathetic effect promotes especially intestinal movements and the secretion of the organs. This digestive secretions are formed and released, which allow in conjunction with the intestinal movement, the crushing, locomotion and digestion of food.
The vagus nerve or the parasympathetic nervous system has a depressant effect on the heart. However, it acts only on the atrium of the heart, which is responsible for the frequency and therefore can only slow the heartbeat ( pulse ) and not directly reduce the impact force ( blood pressure ). Nevertheless, this effect arises, since parasympathetic and sympathetic mutually influence and inhibit each other. The parasympathetic nervous system thus inhibits the strengthening function of the sympathetic heart.
Calming the vagus is not a very common procedure, so there are few suggestions on this topic. Nerves can in principle be paralyzed or destroyed for a while. In the vagus, however, this is useful only on its terminal branches on certain organs ( for example, gastric ulcers ), because it regulates too many important functions in the body. Another obstacle is that the vagus nerve in the body runs very deep and very early gives off very important nerve branches, so it is difficult to access. The best place to reach the vagus during its course is along the neck, as it is rather superficial and has not yet split up. There are theories that one can calm the nerve down by drinking cold water at this point.
Other ways to calm the vagus is to exploit the interaction of the parasympathetic and the sympathetic. The stronger the sympathetic is active, the less active is the parasympathetic 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 "combat and escape situations" and is stimulated in everyday life mainly by stress and during physical activity.
In medicine one usually speaks of an "irritation" when it comes to 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") refers to a nerve reflex, which can be triggered by mechanical pressure on the neck and is used from time to time in medicine. In this case, an intra-body reflex arc is used, which is responsible for the blood pressure regulation. There are small "sensory cells" on the blood vessels of the neck (the halvus ) that measure pressure and send signals to the brain. The brain evaluates the pressure conditions and lowers or increases the blood pressure.
The unilateral "massage" of the carotid artery simulates an increased pressure on the brain, which leads to an immediate fall in blood pressure. This effect may therefore improve the symptoms in patients with critically elevated blood pressure. However, the method is very dangerous, since it can also reflectively lead to a fainting fit. Because of this, it is barely used today and may, if necessary, only be used by a doctor.
To answer this question, one must first clarify what exactly the "disorder" is. Nerves are very sensitive and therefore easy to irritate. However, they may have both a higher activity and a reduced activity. Anyone who has ever tried his elbows knows that also tingling and pain can be a symptom. Symptoms of a disorder result from decreased or increased activity and may be as follows in the vagus: nausea, stomach hyperacidity, constipation or diarrhea, irregular or too fast heartbeat, hoarseness, difficulty in swallowing, headache, increased sweating, cold hands and feet, narrowed pupils, and many Further complaints.
Many of these symptoms are very nonspecific as they occur in many other diseases. However, if several of these symptoms occur at the same time or in succession, a disturbance of the vagus nerve should definitely be considered and clarified by a family doctor.
Symptoms of nerve inflammation are mainly pain, numbness, muscle twitching and loss of function of the nerves. However, since the vagus hardly innervates the skin and muscles, numbness and muscle twitching are rare. Inflammation is therefore noticeable mainly by pain and loss of function. The location of the inflammation can be narrowed down based on the symptoms, but remains difficult to diagnose. The most vulnerable part of the vagus is in the pharynx and affects the upper laryngeal nerve. Symptoms include hoarseness, painful swallowing and coughing.
The vagus nerve usually runs along soft tissue organs and is thus very well protected against pinching. However, there is a spot on the neck where this is common. After the nerve emerges from the base of the skull, it runs along the first cervical vertebra, along with the haloblast and the great jugular vein. Strong rotation of the neck or chronic deformity of the vertebra may result in compression of these pathways ( vagus compression syndrome ).
Vagus nerve stimulation is a recognized therapy for, for example, epilepsy, depression and anxiety disorder. There are different procedures. In an invasive method, a pulse generator is transplanted under the skin. This regularly stimulates the vagus via an electrode. Another non-invasive method is to stimulate the nerve on the pinna through the skin. The arousal is conducted via the nerve into the brain and has stimulating effects there.
The Nervus vagus together with the 9th cranial nerve is responsible for the triggering and control of the nausea. Since the nausea is triggered mainly by nausea, there is a direct connection between the vagus nerve and nausea. Stimulation of the vagus can cause nausea and vomiting. In addition, the vagus promotes the production of gastric juice. This is very sour and leads to increased production also to nausea and abdominal pain.
As already mentioned, the vagus nerve has a dampening effect on the heart rate. When manipulating the heart rate, especially if they have very sudden effects, there is always the risk of a cardiac arrhythmia. The parasympathetic nerve prolongs the transit time within the heart between the atrium and ventricle and slows the frequency. However, it can happen that the transition has taken too long and the ventricle has already made itself independent and works in an irregular rhythm.