Tom Myers discusses the relationship between massage, the client's nervous system and interoceptive sensors of the myofascia.

One of the primary benefits of massage therapy is that it stimulates the nerve endings in the myofascia, leading to a greater sense of interoception—a perception of what is felt within the body.

All therapeutic interventions, of whatever sort, are a conversation between two intelligent systems. Whatever is happening to the tissue under our hands, we are also communicating with the client’s nervous system.

Your nervous system is your meaning maker. The feeling of our touch has to be first taken in by the client’s sensory receptors, and then made meaningful in the central nervous system by comparison with earlier experiences.

Manual therapists deal in perception and therefore must study how the brain perceives the body and the body-mind interface.

Fascia, the Most Wired Organ

There is plenty that science has yet to learn about how we sense the body in motion, and how our clients make sense of our work in themselves.

Fascia happens to be the most wired sensory organ in the body with more sensory nerves in it than you have even in your eye or your tongue, and it has maybe six times more sensory endings than your muscles.

That body you call me is actually a community of about 70 trillion hard-working cells, all surrounded by a fascial network—a kind of sticky, greasy fabric that runs around all those cells and holds them firmly together, yet miraculously adjusts to shape and accommodate our every movement.

The fascial network consists of fibers, made mostly from pliable collagen, stronger than steel, woven into ropes, nets and sheets.

This web runs everywhere. It is very dense in your tendons and ligaments, and much looser in the breasts, cheeks or pancreas—but all your cells are wrapped into this weave.

The other half of the fascial network is a transparent gel of variable mucopolysaccharides. (More simply: snot.)

Basically, your cells are glued together by this mucous, which is everywhere. These sponge-like gels take many forms—the gel in your eyeball, the synovial fluid in the joints, the chondroitin of cartilage—and is more or less watery (hydrated) depending on where it is in the body and what condition it is in.

Your various nerve endings—muscle spindles, Golgi Tendon Organs, Ruffini corpuscles and the rest, all modifications of stretch receptors—are woven and entwined into both the fibrous and the gluey parts of fascial matrix.

One of the primary benefits of massage therapy is that it stimulates these nerve endings in the myofascia, leading, of course, to less somatic amnesia and a more sensitive appreciation of the body, a more complete body image.

Fascia on the Front Line

The fascia of the skin and muscles has a lot to say to the brain about the mind-body connection—more than the muscles themselves. The fascia is on the front line for handling forces, and the various sensory nerves are its messengers to the brain.

In studying how the brain monitors the body, generally known as kinaesthesia, scientists have distinguished proprioception and interoception.

Proprioception is the awareness of one’s body, its position in space and how it is moving. Proprioception allows us to know where our various parts are in relation to one another, to bring a fork to our mouth and not our eye, to chuck a ball accurately or even walk.

We coordinate our proprioceptive signals from our connective tissues and feet, and combine it with our vision and our vestibular information, and after a few “fally-down” months in our first year, we get pretty good at matching our inner sense of our body with the world outside.

(Although you only have to step into a room whose floor was two inches lower than you thought it was going to be to understand how precisely your system “guesses” what it is about to encounter, and how it can be fooled.)

Interoception was originally designated as the signals coming from our organs.

Interceptors are also, like proprioceptors, mostly modifications of stretch receptors. Perception of stretch in the bladder or rectum tells us we need to find a bathroom. Lack of stretch in our stomach tells us it’s time to find lunch. Stretch receptors in our lungs modulate breathing, and similar receptors in our arteries help regulate blood pressure.

In other words, interoception can be described as a sense of the physiological condition of the body, and thus a connection to how we feel about what we feel.

We represent our body from within with interoception. By contrast, we represent how our body is relating to the outside world—what we are touching, what is its weight and what we are moving through—through proprioception.

A nice distinction, but like many of our presumptions about the machinery of our body—never as simple as we would like it to be—not true.

We have recently discovered that interoception extends into our musculoskeletal body as well as our organs. How you feel about what you feel is present in our movement self as well as our physiological self.

Want to feel this? Simply hold one arm out to the side, level with your shoulder; in other words, shoulder abducted and elbow extended. Keep it there as you read on. Right from the beginning, you can appreciate the proprioception—the contraction in the deltoid and trapezius, the joint receptors telling you where your arm is without you having to look at it.

As time passes, though, you will begin to notice other feelings. You will begin to look for excuses to take your arm down. It is not painful, exactly, and there is no tissue damage from holding your arm out there for a few minutes, but now we know it is the interoceptors that are letting you know how you feel about what you feel even in the fascia, muscles and joints.

You can take your arm down anytime now, but it is an interesting test to leave your arm out there as long as possible to watch the process of interoception: how annoyed and agitated you can get as the sensations increase.

Proprioception is emotionally neutral; interoception, from your organs or your musculoskeletal body, as emotion in it.

Followers of Wim Hoff test themselves against these kinds of interoceptive feelings by taking ice baths and such, and there may well be value in expanding the limits of your sensation in this way.

The feeling difference is because interoceptive endings tickle a different part of the brain than proprioceptive ones.

According to fascial researcher Robert Schleip, Ph.D, “These sensations are triggered by stimulation of unmyelinated sensory nerve endings (free nerve endings) that project to the insular cortex rather than to the primary somatosensory cortex which is usually considered as the main target of proprioceptive sensations”

Though interoceptive endings are important to help us maintain homoeostasis in the body, these sensations not only have a sensory, but also come with an affective, motivational or emotional aspect.

The relief you felt when your mom rubbed your boo-boo had been ascribed to the gate control theory of pain, but the mechanism now appears to be through your interoceptors. You may still have the pain, but you feel better about it.

Distressed interoception and altered insular processing is associated with conditions such as irritable bowel syndrome, eating disorders, anxiety, depression, alexythymia (emotional blindness), schizophrenic disorders, post-traumatic stress disorder and possibly fibromyalgia.

It has been proposed that the neural pathways associated with interoception may be considered as a essential component for consciousness, a fundamental part of presence.

3 Tools to Appreciate Your Own Felt Sense

Slower movements. In bodywork, speed is the enemy of sensitivity. The slower you go, the more you feel.

When we do slow movement practices like yoga or tai chi, when we allow the mind to move beyond the actual sequence (the proprioceptive aspect), we can shift our attention to how movements feel in the body (the interoceptive aspect).

Try slowing your techniques down to be able to be able to listen deeply with your hands.

  1. Simple breath meditation. This slowing down is extra special for the autonomic system when you apply it to the breath.

Focus on the coolness of the air as you inhale, and the warmth of the air as you exhale, and watch the feeling inside yourself as a result of the slower breath.

  1. Change your routine. Take your autopilot experiences and turn them into something new.

Doing a particular sequence of yoga or training repetitively will develop mastery of the skill, but introducing novelty by changing your routine may give you access to a deeper listening.

Even changing the position of your massage table in your room or the music you play during sessions may provide a finer tuning of your interoceptive awareness.

  1. Self-massage. When using any self-myofascial release tool, such as a roller or balls, slow down and feel. You will invite a deep parasympathetic response and an overall deeper listening to both proprioceptive and interoceptive cues.

About the Author:

Thomas Myers is the author of Anatomy Trains (Elsevier 2001, 2014) and co-author of Fascial Release for Structural Balance (North Atlantic, 2010). Myers has authored over 100 articles and 50 video programs on anatomy, the fascial network and postural manual therapy. Myers and his faculty offer continuing education for a variety of manual therapists worldwide, and professional certification in Anatomy Trains Structural Integration.