Article

The Vagus Nerve

– Rajen Vakil

Let us deviate from the current series on the chakras to focus on the vagus nerve this week.

From the brainstem emerge cranial nerves that pass through the face, mouth and the rest of the body. The vagus nerve is the tenth cranial nerve. Cranial nerves exist in pairs, so there is a right and left vagus nerve.

The vagus nerve runs from the brainstem right down to the base of the spine, touching all the organs in its path. As the main component of the parasympathetic nervous system, the vagus nerve oversees many functions such as control of mood, immune response, digestion, heart rate and blood pressure. It is one of the connections between the brain and the digestive tract, and relays information to the brain about this area via afferent fibers.

The vagus nerve is the only nerve that is composed of both sensory and motor fibers, both efferent (outgoing) and afferent (incoming). The efferent fibers have a restraining effect and the afferent fibers have an accelerating effect. The efferent fibers are inhibitory and restrain the functions of the organs of the body, the afferent fibers accelerate the functions.

Vagus is a Latin word which means ‘to wander’. A vagabond. As it descends, it looks as if it twists around the body. Because there is a left and right vagus nerve, these vagi (plural of vagus) can possibly be considered to be the physical counterparts of the yogic nerves, the ida and the pingala. Taking this further, we could surmise that at the one end the vagus nerve touches the organs and at the subtle end, it is connected to the chakras.

As explained earlier, the middle nadi or Sushumna is dormant in our present state and it is activated when the sleeping kundalini rises. The chakras are aligned along the Sushumna nadi with ida and pingala running left and right, and crisscrossing at certain points. So, it becomes pertinent to ask whether it is possible to awaken the Sushumna by stimulating the vagus nerve through certain practices.

The dorsal vagus nerve, which goes down the back, influences the body’s fight-or-flight mechanism. Even though it is a sympathetic response, it is this vagus nerve that accelerates the energy to allow one to fight or run away. It is also this part of the vagus nerve that is connected to the kidneys. The dorsal or right vagus nerve is the Pingala nadi in yoga. It brings us to a high state of alertness. Pingala means an orangish brown.

At the same time, the ventral vagus nerve or the one which runs down the front of the body seems more involved with the relaxation response. The ventral or left vagus is the Ida nadi. Ida is moon-like. It cools, relaxes. Ida also means comfort.

In other words, when stimulated in one way, the vagus nerve creates the energy to fight or run away. But if stimulated in another way, it allows us to relax, feel good and maybe eat something. That is, it controls the body’s response in rest and relaxation. We can call one response an active response and the other a passive response.

However, there is a third vagus nerve response that balances both the dorsal and ventral nerves, acting as a neutralizing force. This brings about a beautiful state where we can be very alert and relaxed at the same time. This is the state needed for higher practices of yoga, whether we are in self-observation, self-remembering or effortless effort. It is in such a state that we activate the dormant Sushumna nadi.

For our study, we are interested in increasing our alertness and relaxation simultaneously and holding that state. This can be done by increasing the vagal tone. As our vagal tone increases, we are consciously able to hold this state of alertness plus deep relaxation. It also increases our relaxation response, allowing us to relax very quickly after we are stressed.

Most people have a very weak vagal tone, just enough to allow the fight-or-flight response, and once activated, it takes a long time to come back to a state of relaxation. And even before they reach this state, something else makes them tense again. A weak vagal tone keeps us in a constant state of worry and anxiety. We do not sleep well.

A large number of vagus fibers are connected to the digestive organs. Thus, increasing vagal tone can help cure many diseases of the digestive tract. It is a boon for people with irritable bowel disease, abdominal bloating and gas, and increased acid. It balances the bacteria in the gut. Further, it has a deep impact on autoimmune disorders. It also balances the heart and blood pressure.

There are two ways to profoundly increase vagal tone. The first is by using the humming sound at the end of the Omkar. In the humming, we vibrate the different parts of the mouth – the lips, the teeth, the throat and the palate. The vagus nerve has motor fibers in the pharynx, larynx and soft palate. When we hum and vibrate these different areas, signals of healing, goodness and well-being are relayed to the different organs of the body.

Many of the guttural sounds which come from deep in the pharynx and larynx have a very powerful effect on the ventral vagus nerve, bringing about a very deep state of relaxation.

Through mantra, we consciously create an afferent impulse in the larynx, thus influencing the vagal center. This is very important because normally, the activities of the vagus nerve are automatic and unconscious. In yoga, to control the afferent fibers of the vagus nerve is one of the most difficult tasks.

The second very important way to increase vagal tone is through breathing. The vagal tone is increased by prolonged exhalations. The one that I personally practice, and which leads to a very deep state of alert relaxation or yoga nidra is this: Breathe in for three seconds, breathe out from the mouth for ten seconds and then hold empty for five seconds. While breathing out, make the shape of an O with your lips, vibrating and breathing out as if pushing the air into something (VUMM). This activates the higher qualities of the Svadhisthana chakra. We have seen in the previous articles that the higher qualities of the Svadhisthana bring joy, happiness and love in our lives.

The vagus nerve is divided into three parts. The first part in the medulla consists mainly of efferent fibers and we can say is connected to the Vishuddhi chakra. The second portion, from below the base of the skull down to the solar plexus, has both efferent and afferent fibers. We can say this is the part that connects to the Anahata chakra and the Manipura chakra. The third portion, mainly of afferent fibers, connects the hypogastric plexus and the Svadhisthana and the pelvic plexus, the Muladhara. To understand all this requires deep study and practice.

Next week, we will continue with the Svadhisthana chakra.