This nerve sends sensory information tot he brain: sights, smells, tastes, sounds & controls some motor functions in the body. It's the longest of 12 cranial nerves & is referred to as 'cranial nerve X (or 10)'. There's actually 2 of them: one left side, one on the right, but they are often talked about as one.
In Latin 'vagus' means 'wandering' which fits since it wanders throughout the body from the brain stem to the heart, lungs, stomach, digestive tract, liver, kidneys & spleen. It works with the parasympathetic system which is responsible for 'rest & digest' response. This system regulates internal organ functions i.e. digestion, heart rate, respiratory rate as well as reflex action like gagging, sneezing & swallowing.
Signals go up & down this nerve impacting various parts of the body including the brain, heart, lungs & gut. In the brain, it affects moods, helps make & store memories & is essential for human connection. Slows the heart rate down, allows the lungs to breather, helps the gut bacteria communicate with the brain along the microbiome.
Since it runs through much of the body & impacts so many bodily functions, it can trigger a wide number of symptoms. Loss of gag reflex, hoarseness, whispering or a nasal voice, irregular heart rate, changes in blood pressure, decrease in stomach acid, acid reflux or GERD, anxiety, headaches, depression, IBS & more.
Vagus nerve stimulation has been shown to be effective for various conditions like depression, Alzheimer's, obesity & more. It's possible to stimulate the nerve on your own: exposing yourself to cold temps, breathing exercises, yoga, meditation, singing, chanting, exercising, laughter, massage, eating probiotics & omega 3 fats. Our physical & mental well-being are intimately interwoven & the vagus nerve is largely why. It's one of the most important nerves in the body!!