Updated: Mar 7
In previous articles i’ve introduce you to what fascia is as an organ, and later its important role in managing the structural integrity of our bodies. In this article I give a pretty detailed overview as to how fascia facilitates a lot of the communication of going on inside us.
Nerves & Mechanoreceptors
To start, it’s important to know that the body-wide fascial network has more nerve endings in it than the skin does. It is also 10 times more innervated than muscle tissue, making it the most sensitive organ in the body (Myers 2011). Dr. Robert Schliep claims, "our central nervous system receives its greatest amount of sensory input from myofascial tissues."
The somatosensory system is body's system which detects touch and extrasensory stimulus. It is made up of afferent neurons (nerve cells) that relay sensory information to the central nervous system (spinal cord & brain; “CNS” henceforth). This system regulates the functions of:
proprioception (sensing self-movement, body positioning & posture)
extroception (sensing external world through the skin)
interoception (gathering information about condition of the body in search for homeostasis)
nociception (sensing pain)
Fascia and the types of receptors (nerve endings) that lie within it, are the basis for these functions. Why? Because the fascial network is a signaling network which is sensitive to pressure, changes in posture and movement.
How does this happen? Through sensory (afferent) nerve cells, which have different nerve endings according to their function called, receptors. These receptors pick up external stimuli and send it to the CNS via action potential in neurons (action potential is the ability to convert a stimuli into an electrical signal). In brief, this is the key aspect of cell-to-cell communication.
Mechanoreceptors are then the sensory receptors which detect and react to mechanical pressure, such as touch, pressure, vibration and stretch. That pressure is then converted into an electrical signal, which is sent to the CNS, leading to proprioception; that is, the ability to determine our muscle activity and joint position.
Through this transference of pressure and deformation into electrical signals, these mechanoreceptors send information to the CNS (the brain) telling it the position and posture of the various parts of the body.
Yet, this also happens with our internal organs. Mechanoreceptors & free nerve endings pick up changes in the the physiological state of viscera and relay that info to the brain, informing us of our need to maintain homeostasis (Schleip and Jäger, 2012). This is called interoception, and the degree of bi-directional communication here and its sensitivity dictates how well we can feel the somatic sensations of emotion (something I refer to as felt-sense).
Fascia contains four types of these mechanoreceptors:
1. Golgi organs
measure load by sensing the stretch in fibers
when stimulated, triggers a relaxation response in muscle fibers which are linked to the connective tissue
inform the central nervous system of shear forces in the soft tissues
trigger the central nervous system to change the tone of tissue
remain discharging in response to continuous stimuli
highly sensitive to sheer loading
exist in superficial fascia
respond to vibration & rapid changes in pressure
In bodywork, "stimulated only by high-velocity thrust manipulations and vibratory or oscillatory techniques" (Schliep 2016)
rapidly adapting & very sensitive to changes in stimulation
mediate sensation of joint motion
exist in superficial fascia
4. Interstitial receptors / type III and IV receptors
exist abundantly in fascia, between fibrous tissue
form a net connected with the extracellular matrix
originate in free nerve endings
mostly non-myelinated receptors (apart from type III)
slower than the type I and II sensory fibers
poly-modal: responsive to more than one kind of stimulation
Cells & The Extra Cellular Matrix
Remember in the first article, I talked of how fascia is made up of two parts: Extra Cellular Matrix (ECM) + Connective Tissue Cells. Now, the ECM connects the inner network of each cell to the mechanical state of the entire body. It is the space into which and from which cells excrete and absorb their nutrient, energy and waste. Thus the components of the ECM pick up info from each cell and relay that information elsewhere in the body. Fascia therefore really does acts as a communication network.
Another way fascia supposedly serves as a communication system is via what’s known as the pizeo-electrical charge. This is when mechanical pressure causes the electric centers inside a crystal lattice to separate, resulting in a small electric charge on the surface of the crystal.
Because fascia behaves like a "liquid crystal", energy worker & fascia researcher, James Oschaman proposes that fibroblasts (cells responsible for producing and breaking down collagen fibers), may be responsive to these electric charges. According to Oschman, body movements create electric fields that spread through tissues and inform cells of the nature of the load, movement & other activity elsewhere in the body.
Contracting Properties of Fasica
In 1996, fascia researchers, Staubesand and Dr. Li studied the fascia in humans for several years using electron photomicroscopy. They found smooth-muscle-cells within this fascia's collagen fibers and a rich supply of sympathetic and sensory nerve tissue.
Based on their findings, they concluded that these smooth muscle cells likely help regulate fascial pre-tension independently of muscular tonus. Staubesand also stated that the stiffness of fascia (contraction) is most likely due to sympathetic activity of the autonomic nervous system.
Later, Dr. Robert Schleip conducted further research into fascia’s contractile properties and found fascia is not just a passive tissue that reacts to external forces - it has the ability to contract and change its tonus independently of surrounding muscles and responds to stress unconsciously. It is believed this happens due to two physiological elements found in fascial matrix:
Myofibroblasts cells, which can actively contract in a manner similar to smooth-muscle-cells are directly responsible for fascial tension. This tension influences force transmission, energy storage and communication. Mechanical load can also alter the density and orientation of collagen fibers. It has also recently been shown how fibroblasts cells can transition into myofibroblasts in response to these mechanical load changes.
It’s proposed that mechanoreceptors (Golgi tendon organs, Ruffini endings, Paciniform endings) may also be contributing to these smooth-muscle-like contractions and communicating with the central nervous system regarding the amount of shear forces within the connective tissue.
Again, it’s important to note that the fascial matrix has 10 times more proprioceptors than muscle. This helps us react to our environment faster than our conscious mind can respond, whether we are reacting to an opposing player, dodging a moving car or removing our hand from a hot object.
Fascia contraction helps the body’s stability and energy expenditure. The fact that fascia is a rich sense organ that can contract and feel also impacts movement. Therefore, understanding it has big implication for massage therapists, physical therapists, trainers and orthopedists.
Further research is required to understand how fascia and muscle contract together, how these contractions affect movement, and their implications for professionals.
Fascia & The Influence On Mood
Considering now how fascia really is the underpinnings of the body’s communication system, particularly for movement and pain, let’s turn to the ways in which fascia is both influencing and influenced by our mood.
It’s been shown that deep mechanical pressure, applied slowly and steadily (as in deep tissue massage) stimulates the ruffini receptors. This stimulation leads to an increase in vagal activity, which affects the flow of fluids and tissue metabolism in that local area. Additionally, this increase in vagal activity leads to relaxation of muscles throughout the body, as well as a decrease in emotional arousal and a more peaceful state of mind.
It’s been shown that fascial mechanoreceptors are closely connected to both the autonomic nervous system and the endocrine system, and they are important for communication within the latter. The enteric brain (your 'gut-brain') has many sensory neurons that are mechanoreceptors, which can activate important neuroendocrine changes among other responses.
Sympathetic Activation & Stress Leads to Stiff Fascia
A study at Yale University School of Medicine, demonstrated that if you stimulate the sympathetic nervous system, it sends out a small protein (cytokine TGF-beta-1) to elicit an immune system response, (Schleip, 2016).
Schleip tells us that,
“TGF-beta-1 is also known as the most reliable and most potent physiological stimulator of myofibroblast contraction. [So], an increase in TGF-beta-1 can induce tissue contracture mediated by myofibroblasts. These studies indicate that an increase in sympathetic activation, as caused by stress, can lead to increased fascial stiffness...... "
To map this out: stress → stimulates sympathetic nervous system → release of cytokine TGF-Beta-1 → immune system response + stimulation of myofibroblast contraction (fascial tension)
With all this in mind, I will soon be writing as to how fascia (with it’s role in structural integrity, sensitivity, movement and emotion) is the core physiological component impacting our sense of embodiment: that is, how the condition of our fascia impacts how present we are to our bodies & their subtle sensations.