The Synergistic Relationship Between Muscles, Fascia and Nerves
Muscle fibers contract (shorten) in response to neural signaling from the brain to the motor unit – a segment of muscle tissue defined by one motor neuron and the muscle fibers it innervates. When the brain sends a message to the motor neuron, all of its associated fibers contract simultaneously – a phenomenon called the “all or nothing” principle of muscle contraction.
The number of muscle fibers per motor unit varies widely throughout the body, depending on their purpose and location. Generally speaking, small motor units responsible for precise, controlled movements such as those of the eye and hand muscles, may have only 10–100 muscle fibers per motor unit. By contrast, larger muscles like the quadriceps or glutes may have thousands of muscle fibers per motor unit, capable of generating powerful forces, but with less precision.
Muscles and nerves do not act alone. Muscle actions are controlled and guided with the help of fascia, a complex web of thin, tough connective tissue that surrounds and connects muscles, engulfs the visceral organs, and holds the body’s structures in place during dynamic movement. Fascia is strong and elastic, able to stretch and contract as the body moves, providing elastic tension that complements muscle action.
Fascia itself is densely embedded with sensory nerve endings, including proprioceptors, nociceptors, and mechanoreceptors – neural bodies that send feedback to the brain about the body’s position in space, as well as sensations of pain and pressure. Fascia is estimated to have over 250 million nerve endings, making it a major pain generator when injured. Fascia, muscles and nerves act synergistically to inform the brain of the body’s state at any given time.
Fascia is made up of collagen fibers, lubricated by hyaluronic acid – a slippery gel-like substance able to attract 100X its mass in water. In addition to its elastic and neural properties, facia provides a slippery surface that allows nerves and blood vessels to glide freely among larger structures while allowing larger structures to move in harmony, without friction.
When fascia is injured, it can become dense and sticky, losing its elastic and slippery properties and adhering to other structures. Nerves and blood vessels can become entrapped in densified fascia, causing pain and restricting movement. Muscle action can be impaired, disrupting motor unit recruitment patterns and reducing movement efficiency.
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Lev Kalika 
