Protective Reflex Arcs, Pain, and Muscle Guarding Reflexes

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Article 5 of 6 of "That Was Not A Muscle" companion series

Protective reflex arcs are automatic responses that protects us from harm. Their immediate and involuntary nature are possible because these responses bypass the brain to act directly on the spine. Let’s illustrate the mechanisms with an ankle sprain.

The moment that sensory neurons in the ankle joint detect the abrupt disruption of tissue mechanics and integrity, they send signals that travel through their axons to the Dorsal Root Ganglion (DRG), where the signals get processed before continuing to the dorsal horn, where the signals get relayed at the interneurons.

Recall we had mentioned that the interneurons also synapse with the motor neurons in the ventral horn where they activate or inhibit motor neurons. The interneurons relay the protective signals to the motor neurons which then execute a protective action. In the case of the ankle sprain, this nets to contracting the injured limb while standing on the uninjured leg.

This protective loop is known as a protective reflex arc, spinal reflex arc, or colloquially just as a reflex. It's instantaneous and beyond our conscious control. The signal went from the ankle to the spine and instantly to the legs for protection and balance without ever going to the brain. What goes to the brain is the pain signal in a three-neuron sequence.

The pain signal arrives to the dorsal horn via the sensory neuron, the first order neuron in this sequence. The signal is relayed to the opposite side of the spine and then upwards through the next neuron in the sensory upstream sequence, or second order neuron, which goes from the spine to the thalamus in the brain via the ascending tract, the equivalent of a spinal highway. The signal then is relayed to the thalamus, the proverbial gate keeper. From the thalamus, the signal will be relayed to the sensory area of the brain via a third order neuron. The pain signal gets processed at the sensory area to produce a conscious response.

The manifestation and intensity of these responses is dependent on the extent of the injury and the perceptual state of the individual. Factors like shock, heightened emotional states, or other sources of endorphins, are known to momentarily dampen or even suppress pain signals. But as the biochemistry around the injured ankle commences the healing process, the individual will experience not only pain, but also palpable and measurable changes in their biomechanics as the muscles engage in a protective response.

Neural Convergence, Protective Reflex Arcs, Guarding Reflexes, and Symptomatology

Tight and knotted up muscles are common when healing from an injury. Known as muscle guarding reflexes, these normal but involuntary contractions are hypothesized to be attempts by the body to decompress the affected area and to discourage us from disrupting the healing process through conscious actions.

In theory, these reflexes should dampen once the injury is healed, but many patients carry them for months, even years, after their injuries have physically healed. Often, these reflexes seem to show up seemingly out of nowhere in uninjured areas. This can now be explained by analyzing neural convergence at a deeper level.

Let’s recall that the source inflammation travels to the dorsal horn of the spine where it affects all neurons converging in an interneuron. Synapsing with the interneuron on the opposite end, we find the motor neurons, which are in charge of voluntary and involuntary movement, and exit the spine from the ventral horn.

The combined activation and inhibition of these motor neurons from this inflammation is what triggers the muscle guarding reflexes. As long as there is inflammatory stasis activating this response, the muscle guarding reflexes will continue acting as if we were experiencing an injury, thus recreating the protective mechanisms and pain signals. The most evident examples can be seen in the activation of two specific motor neurons.

Who has not experienced the neck, shoulder, or hip knots and hypertonicity we love to pound with our hands or bizarre gadgets? That’s the result of the activation of the larger Alpha Motor Neurons, which innervate the muscle fibers responsible for contraction.

But when muscles lose flexibility without necessarily becoming hypertonic, that’s the result of the smaller Gamma Motor Neurons. These motor neurons do not innervate the muscle fibers but the muscle spindles, which are in charge of the stretching reflex and their activation produces an elevated stretch reflex, which then compromises range of motion. Think of hamstrings that while not hard or knotty, are tight and tense, even at rest.

The effects of the aforementioned reflexes are seen by conventional therapy as causal and treated with aggressive modalities. But because this is a reflexive response, the muscular tightness and knots will remain—even at rest—until the source inflammation dissipates.

Motor neurons are NOT confined to the musculoskeletal system and they’re also present in organs and vasculature. Depending on their location, the guarding reflexes may also affect significant portions of physiological systems. To compound on the issue, the muscle guarding reflexes exacerbate fascial contractions that aggravate tissue inflammation. This eventually manifests as symptoms that mainstream thinks causal or, if present for prolonged periods, as disease.

Although we make it clear that we’re only treating dysfunctions, not disease, we also understand that aberrant protective reflex arcs triggered by trapped inflammation could be at the genesis of the many conditions that arrive to our practices. Our job is to interrupt the disruptive cycle. We study, train, and hone our skills to identify the source inflammation and drain it because we know that our bodies can handle the rest.

Now that you’re acquainted with the main aspects of the mechanics of our modality, you’ll be able to appreciate how Counterstrain removes the trapped inflammation, and how it does so gently.

And that is the topic of our next and last installment.

Until next time, I wish you a joyous and pain-free life.

Certified Counterstrain Therapist - CSC I

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The topics in this series are covered in-depth in the book That Was Not A Muscle, available now at your favorite online book retailer.

All photographs, illustrations, graphics, videos, and other media contained in or associated with this publication are the intellectual property of Izzy Sanchez, Integrated Healing and Strength Systems, Inc., and Mar en Hoguera Media, LLC, and are protected under United States and international copyright laws. Unauthorized reproduction, distribution, display, modification, publication, or use of these materials in any form is strictly prohibited. Any infringement of these rights may result in civil and/or criminal penalties, and violators may be subject to prosecution to the fullest extent permitted by law.

All biomedical illustrations created with BioRender.