5 Divisions of the Nervous System
The nervous system and increasing its resiliency is an important benefit to slow yoga. Unfortunately, yoga teachers talking about yoga’s benefit to the parasympathetic system has become like the grocery stores labeling gummy bears as gluten free. OK, maybe not the best analogy, but the point is that yoga benefits the whole nervous system. We over use the benefits to the parasympathetic nervous system because its so relatable to many people and we want everyone practicing yoga.
So let’s take a moment and learn about the 2 main Systems; Central Nervous System (CNS) and Peripheral Nervous System (PNS). The PNS is then broken down into 3 subdivisions; Somatic (SNS), Autonomic (ANS), and Enteric (ENS). The ENS is a subdivision of the ANS, but is said to work independently of the CNS so it may not always be included in discussions about the nervous system. Not to be forgotten, The Sympathetic and Parasympathetic systems work in conjunction with one another as part of the ANS. Head here for a diagram if you’re head hurts from all of those acronyms. I’m doing my best to explain a complex, detailed system at its simplest.
Central Nervous System
The brain and spinal cord make up the CNS. Therefore, it performs all three functions of the nervous system; sensory, motor, and integration. The brain and spinal cord collect information from our physical and emotional senses as it relates to our external and internal world and act as the control center (command station) to ensure our survival. Using yoga as a tool to improve Proprioception is a way in which we make the CNS more efficient.
Peripheral Nervous System
Separate from the brain and spinal cord are the remaining nervous system tissues; motor neurons, and sensory receptors and neurons. Neurons (nerve cells) carry messages through electrical pulses through our nervous system. A receptor is what receives information and generates nerve impulses for transmission. The motor neurons collect messages from the CNS and send them to the appropriate body organs. On the other hand, the sensory receptors and neurons collect messages and send them to the CNS. In Summary, motor neurons communicate from CNS to PNS, but sensory neurons and receptors communicate from PNS to CNS. As mentioned previously, there are 3 subdivisions of the PNS; Somatic, Autonomic and Enteric.
Somatic Nervous System
The Somatic System is the voluntary system which we have control over that regulates skeletal and muscle movement. Basically, as you practice yoga and decide where to place your limbs and when to contract muscles etc, you are using the SNS. However, emotional and physical trauma can result in us holding physical patterns that inhibit our fluidity of motion. Using yoga as a tool to discover and heal these patterns will help bring this nervous system into equilibrium. I don’t mean making sure everyone’s body works like everyone else’s. The goal is to understand an individual’s own skeletal and muscular structure and what balance of the SNS means for each individual. Yoga helps us to find our physical blocks that interfere with smooth transfer of energy throughout our body. Using intentionaly subtle movements in our yoga practice helps bring awareness we may otherwise not notice in our day to day routines.
Autonomic Nervous system
The ANS is the involuntary system generally out of our control that regulates communication from our internal organs to the CNS and vice versa. One of the three sub divisions, the enteric nervous system, can act independently of the CNS. The other two subdivisions, Sympathetic and Parasympathetic, work in conjunction with each other in response to internal and external stimuli.
“The nervous system dance is complex and highly changeable – that’s why the word “homeostatic” is not really accurate. “Homeodynamic” makes more sense. It’s this ability to adapt that underlies our capacity for resilience.” Kristine Kaoverii Weber
Sympathetic Nervous System
The Sympathetic system is know for its fight or flight response that increases things like heart rate and blood pressure simultaneously in response to stress. It is a much needed part of our system that gets a bad rap due to our inability to pay attention to the impact of our own choices that keep us under constant stress (not shaming. I’m guilty of this too). Also, the effects of trauma can push the system into overdrive as well. Yoga practices that focus safely on improving our interoception help us to build the window of tolerance between the SNS and PNS.
Parasympathetic Nervous System
The Parasympathetic system is know for the rest and digest response that increases things like digestion and salivation while reducing the heart rate. However, the problem underemphasized in yoga is that some individuals have their PNS in overdrive. The SNS does not respond appropriately to internal or external stress (potentially as a result of trauma or chronic stress) and is suppressed . I love this image that explains the window of tolerance between the SNS and PNS. Unfortunately, the constant focus on how yoga makes us feel great by jump starting this rest and digest system leaves out a large portion of society dealing with depression, poor self care, etc. Slow yoga is a great tool for expanding our window of tolerance.
Enteric Nervous System
And finally, the ENS is the system also known as the intrinsic system or “Gut Brain”. As mentioned before, it can act independently of the CNS with its own reflexes. It is a division, that I myself need to dig further into, but as expected, it is tied to mood. Interestingly, most of the body’s serotonin is produced in the digestive system. Serotonin is known as one of our happy chemicals that that contributes to well being. The ENS also plays an important role in our immune system. It receives and sends messages to release inflammatory chemicals that might result in diarrhea or vomiting. When the ENS is not efficient or out of balance, any individual with a chronic illness can explain the frustration in trying to understand what’s going on within their body. Yoga practices that work towards increasing vagal tone and bringing awareness to sensations of the gut may help with the efficiency of messages between the gut and the brain. Please note that “trusting your gut” does not always work when other parts of the nervous system are misinterpreting messages. Yoga is complimentary to good therapists and doctors.
Its is fair to say that we are complex beings with awesome systems attempting to keep us balanced. Slow yoga is a tool that helps offset the damage done by environmental as well as internal stressors. We need more yoga that trains the nervous system, is breath centric with simple movement and helps individuals with chronic illness. Please reach out with any questions and I’ll do my best to answer. May you have less worries and more smiles!