There are 12 cranial nerves in the body that help link the brain with the head, neck, torso, and more. They originate in the brain, and each has a different function that relates to sensation or movement. Some are pure motor nerves (M) III,IV,VI,XI,XII, some are pure sensory (S) I, II others are both sensory and motor (B) V, VII,IX,X.
- I; Olfactory. Sense of smell (S)
- II; Optic. Vision (S)
- III; Oculomotor. Eye/eyelid control, pupil, lens shape (M)
- IV; Trochlear Eye movement, superior oblique (M)
- V; Trigeminal. Chewing, sensation for head and face (B)
- VI; Abducens. Lateral eye movement, lateral rectus (M)
- VII; Facial. (B)
- VIII; Vestibulocochlear. (S)
- IX; Glossopharyngeal. Salivation, taste, swallowing (B)
- XI; Accessory. Head, shoulder control (M)
- XII; Hypoglossal. Tongue movements, speech, swallowing (M)
The vagus nerve has both. Research has shown tapping into the largest cranial nerve in the body can affect both emotional and physical health. It means “wandering” in Latin and is the longest cranial nerve starting in the brain and extending through the face and thorax to the abdomen. Its motor components originate in the autonomic nervous system that controls the actions we do unconsciously such as swallowing, speech, digestion, breathing, cardiovascular activities and reflexes such as coughing and sneezing. It may also be a link in the gut- brain axis that may be an important key in impacting obesity and depression. It has two motor components- somatic, which creates sensations in the skin or muscles, and visceral, which creates sensations in the organs.
It is also highly integrated into the parasympathetic nervous system- a network of nerves that relax us during periods of stress or danger. As opposed to the sympathetic that causes the fight or flight response. This is an automatic response to a perceived threat. Real, or not, if we are fearful, worried, or anxious, the sympathetic nervous system is activated which triggers a cascade of stress related actions. Staying in a fight or flight mode shuts down the gastrointestinal tract and surges circulation to the vital organs required to survive (e.g. heart, lungs, muscles) by releasing hormones and neurotransmitters that cause a hyper-vigilant state of awareness. Once the danger passes it can take up to an hour to recover, reset, and return to normal. But those of us who stay in a perpetual state of flight or flight never relax, ultimately shredding our skeletal tissue, increasing blood pressure, dilating pupils, as well as heart and breathing rates. It can’t be sustained.
The vagus nerve is important in pain syndromes because it inhibits inflammation, oxidative stress and sympathetic activity that can cause tension in muscles by activating regions in the brain that not only oppose the areas of the brain that respond to pain, the “pain matrix,” but might actually influence the analgesic effects of opioids. It does this by releasing acetylcholine, its principal neurotransmitter that has anti- nociceptive (the sensory nervous systems way to respond to noxious stimuli) effects. It also appears to alter the psychological processes that modulate how we perceive pain through the parasympathetic system. When the vagus nerve is activated, it triggers a “rest and digest” phase where we are calm and relaxed.
As discussed in past posts the body’s natural way of responding to injury or disease creates an inflammatory response that should end when the initial injury is resolved. In those cases where it persists, chronic pain results. Activating the vagus nerve can accelerate the body’s anti-inflammatory response by calming the nervous system and lowering the production of cytokines– proteins that control growth and activity of other immune system cells. In a 2021 study, researchers used a vagus nerve stimulating device on rheumatoid arthritis patients for twelve weeks. They found evidence it caused a clinically lower level of DAS28-CRP and tumor necrosis factor (TNF). Both are inflammatory markers in the body that correlated with clinically improved pain from respondents.
The vagus nerve is our superpower. It’s the most influential nerve in the parasympathetic system. It counteracts the fight or flight reflex and helps us to develop healthier ways to respond to stress and become resilient- able to recover and pull ourselves through trauma and troubles quickly.
When stimulated it,
- Reduces cortisol levels
- Helps to achieve homeostasis which then affects all of our physiological functions.
- Improves absorption of nutrients and digestion.
- Decreases systemic inflammation
- Improves short term memory
- Produces feel good hormones like endorphins.
- Lowers blood pressure and heart rate
- Boosts the immune system
- Relieves anxiety
- Stimulates stem cells.
We become more compassionate, clearer, calmer, thoughtful, loving and relaxed. We just feel better overall. And that decreases our pain levels.
Next week I’ll discuss ways to stimulate our own vagal nerve responses.
-https://www.thelancet.com/journals/lanrhe/article/PIIS2665-9913(20)30425-2/fulltext
-https://www.healthline.com/human-body-maps/vagus-nerve#other-considerations
-https://www.sciencedirect.com/science/article/pii/S2452073X17300041
-https://pubmed.ncbi.nlm.nih.gov/26493698/
-https://pubmed.ncbi.nlm.nih.gov/24451632/
-https://www.nature.com/articles/s41586-021-04001-4
-https://www.forbes.com/sites/womensmedia/2021/04/15/what-the-vagus-nerve-is-and-how-to-stimulate-it-for-better-mental-health/?sh=f94c0d76250c
-https://pubmed.ncbi.nlm.nih.gov/26209457/
-https://arthritis.ca/treatment/emerging-treatment-and-research/neurostimulation#
-https://www.thelancet.com/journals/lanrhe/article/PIIS2665-9913(20)30425-2/fulltext