Anatomy and Operate, Diagram, Stimulation, Circumstances

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There are 12 cranial nerves within the physique. They arrive in pairs and assist to hyperlink the mind with different areas of the physique, equivalent to the top, neck, and torso.

Some ship sensory info, together with particulars about smells, sights, tastes, and sounds, to the mind. These nerves are often called having sensory features. Different cranial nerves management the motion of assorted muscular tissues and the operate of sure glands. These are often called motor features.

Whereas some cranial nerves have both sensory or motor features, others have each. The vagus nerve is such a nerve. The cranial nerves are labeled utilizing Roman numerals based mostly off of their location. The vagus nerve can also be referred to as cranial nerve X.

The phrase “vagus” means wandering in Latin. This can be a very applicable identify, because the vagus nerve is the longest cranial nerve. It runs all the way in which from the mind stem to a part of the colon.

The sensory features of the vagus nerve are divided into two parts:

  • Somatic parts. These are sensations felt on the pores and skin or within the muscular tissues.
  • Visceral parts. These are sensations felt within the organs of the physique.

Sensory features of the vagus nerve embrace:

  • offering somatic sensation info for the pores and skin behind the ear, the exterior a part of the ear canal, and sure components of the throat
  • supplying visceral sensation info for the larynx, esophagus, lungs, trachea, coronary heart, and many of the digestive tract
  • enjoying a small position within the sensation of style close to the basis of the tongue

Motor features of the vagus nerve embrace:

  • stimulating muscular tissues within the pharynx, larynx, and the taste bud, which is the fleshy space close to the again of the roof of the mouth
  • stimulating muscular tissues within the coronary heart, the place it helps to decrease resting coronary heart charge
  • stimulating involuntary contractions within the digestive tract, together with the esophagus, abdomen, and many of the intestines, which permit meals to maneuver by way of the tract

Discover the interactive 3-D diagram under to study extra concerning the vagus nerve.

To check the vagus nerve, a health care provider might examine the gag reflex. Throughout this a part of the examination, the physician might use a delicate cotton swab to tickle the again of the throat on each side. This could trigger the particular person to gag. If the particular person doesn’t gag, this can be attributable to an issue with the vagus nerve.

Nerve injury

Injury to the vagus nerve can have a spread of signs as a result of the nerve is so lengthy and impacts many areas.

Potential signs of injury to the vagus nerve embrace:

  • issue talking or lack of voice
  • a voice that’s hoarse or wheezy
  • bother ingesting liquids
  • lack of the gag reflex
  • ache within the ear
  • uncommon coronary heart charge
  • irregular blood strain
  • decreased manufacturing of abdomen acid
  • nausea or vomiting
  • stomach bloating or ache

The signs somebody may need depend upon what a part of the nerve is broken.

Gastroparesis

Consultants imagine that injury to the vagus nerve may trigger a situation referred to as gastroparesis. This situation impacts the involuntary contractions of the digestive system, which prevents the abdomen from correctly emptying.

Signs of gastroparesis embrace:

  • nausea or vomiting, particularly vomiting undigested meals hours after consuming
  • lack of urge for food or feeling full shortly after beginning a meal
  • acid reflux disorder
  • stomach ache or bloating
  • unexplained weight reduction
  • fluctuations in blood sugar

Some individuals develop gastroparesis after present process a vagotomy process, which removes all or a part of the vagus nerve.

Vasovagal syncope

Typically the vagus nerve overreacts to sure stress triggers, equivalent to:

  • publicity to excessive warmth
  • concern of bodily hurt
  • the sight of blood or having blood drawn
  • straining, together with attempting to having a bowel motion
  • standing for a very long time

Bear in mind, the vagus nerve stimulates sure muscular tissues within the coronary heart that assist to sluggish coronary heart charge. When it overreacts, it could trigger a sudden drop in coronary heart charge and blood strain, leading to fainting. This is named vasovagal syncope.

Vagus nerve stimulation entails inserting a tool within the physique that makes use of electrical impulses to simulate the nerve. It’s used to deal with some circumstances of epilepsy and melancholy that don’t reply to different therapies.

The machine is normally positioned underneath the pores and skin of the chest, the place a wire connects it to the left vagus nerve. As soon as the machine is activated, it sends alerts by way of the vagus nerve to your brainstem, which then transmits info to your mind. A neurologist normally applications the machine, however individuals typically obtain a handheld magnet they’ll use to manage the machine on their very own as nicely.

It’s thought that vagus nerve stimulation might assist to deal with a spread of different situations sooner or later, together with a number of sclerosis, Alzheimer’s illness, and cluster headaches.



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