The Brain and the Mouth
and Everything in Between
What is the science between the brain and the mouth?
There are twelve cranial nerves (nerves that extend to the body directly from the brain, as opposed to via the spinal cord) - of those, five connect to the oropharynx (mouth and throat). Those five are the facial, hypoglossal, glossopharyngeal, trigeminal, and vagus. Most structures in the body get one, maybe two, important nerves to communicate with the brain. The mouth is so complex and so important to emotion, breathing, nutrition, and head/neck posture that the brain needs almost half of its cranial nerves to relay important information back and forth!
The vagus nerve connects directly from the brain to the mouth and throat (oropharynx), all the way down the digestive system, and to the heart and lungs. However it does not connect to the tongue muscle itself. The other four nerves - facial, trigeminal, glossopharyngeal and hypoglossal - are the nerves that are excited and calmed by the Froggy Mouth (that we use with OMT) from Dr. Patrick Fellus. The Froggy mouth works by non-consciously forcing the lips to relax, thus the tongue must engage more functionally and this engages the throat. The brain uses this information from the lips to send to the prefrontal cortex and medulla oblongata, which communicate with the vagus nerve which does its thing regulating the heart and lungs (which, as you know, allows us to breathe in a manner related to our emotion in the moment.)
How can I become more in tune with my body?
Anyone who is struggling to be in tune with their own body/Vagal Tone can use a smart watch, Oura Ring, or other Heart Rate Variability (HRV) tracker to track their vagus nerve health! (I personally use the Oura ring, and in the Oura Ring the HRV is recorded in the Readiness section.) HRV indirectly shows us our Vagal tone by tracking its effects on the time between heart beats. When we are calm, and our heart is beating once per second or less, it does not beat every second or at some equally-spaced time. Our heart, at its healthiest, beats in time with the nerves that are communicating with it. We are not robots with perfect time, so when our bodies are in homeostasis, we are able to continuously respond to the communiques our body and brain are sending back and forth to each other. We now know that normal resting heart rhythm is highly variable. If the heart is beating at exact intervals, it's actually a sign that the body is very weak or sick, because it is not responding to the rhythm of our body and brain! It has lost (at least for the moment) the ability to self-regulate. Heart Rate Variability is an amazing indicator of a body moving towards health or illness - it’s better than anything else we can track so far. I track this in my own body and I have several studies on HRV and what it tells us.
How does Orofacial Myofunctional Therapy come into all this?
Any OMT worth their salt understands the relationship between the mouth, nose and brain/cranial nerves. We have training in not just muscles, but breathing too.
First, the vagus nerve shows healthy function when we are feeling positive emotions such as safety, calm, happy, gratitude, and compassion. Studies show that HRV (the best way to measure vagal tone without an electrocardiogram EKG) is positively affected when we feel these positive emotions spontaneously or intentionally! How cool is that??? Studies show that the muscles of the face in showing emotion, and the tongue muscle’s gentle pressure on the roof of the mouth/floor of the nose give the brain the information that the body is feeling these emotions and tells the vagus nerve to tell the heart that all is good there and to pump in a healthy manner. Second, studies show that nasal breathing, at 6 breaths per minute also improves vagal tone and heart rate/heart rate variability (HR/HRV). But you don't have to do both at once, you can pick one or the other and get results. However, allowing your face to relax and smile and breathing slowly is more effective than just breathing retraining alone.
It is my job to help people do a bit of both. People come to me because their TMJ specialist or sleep dentist told them they need to open the muscles of their airway via training the tongue to sit in a supportive position in the mouth (on the roof of the mouth) (controlled directly by the vagus nerve). That is my number one goal for them, however, I know that they are more likely to reach their health goals if they use all their face muscles to the benefit of their brain and not just opening their airway. Retraining all of the mouth and face muscles so they support each other so the patient does not revert back to their old compensations is a more comprehensive approach that results in longer-term success and health.
While the Vagus nerve does not directly innervate the tongue, the tongue plays a crucial role in the tightly-interconnected ecosystem of cranial nerves, including the vagus nerve. It innervates other parts of the mouth/throat and the brain uses the information from all the cranial nerves and sends it to the vagus nerve to react to our surroundings. The entire mouth works as one for improved brain and body function. If something in the mouth is not functioning well, the rest of the mouth will compensate, leading to strain, fatigue, and pain communicating to the brain that something is off.
Want to learn more?
This link is my favorite whitepaper discussing the benefits of tracking and improving HRV as a way to improve Vagus nerve health (aka vagal tone) All the studies about positive emotion and healthy vagus nerve are listed at the bottom of this paper.