Fascia is connective tissue fibers, primarily collagen, that form sheets or bands beneath the skin to attach and separate muscles and other internal organs. Fascia are classified according to their distinct layers, their functions and their anatomical location: superficial fascia, deep (or muscle) fascia, and visceral (or parietal) fascia. Like ligaments and tendons, fascia are connective tissues, containing closely packed bundles of collagen fibers. Fascia are consequently flexible structures able to resist great tension forces until the wavy pattern of fibers has been straightened out by the pulling force. These collagen fibers are produced by the fibroblasts located within the fascia.
Fascia are similar to ligaments and tendons as they have collagen as their major component. They differ in their location and function: ligaments join one bone to another bone, tendons join muscle to bone, and fascia surround muscles or other structures. This connective tissue around muscle is highly sensitive to pain. In fact, the fascia is about as sensitive to pain as our skin. Needles inserted into the thick outer layer of fascia surrounding the muscle hurt more than needles poked into muscle tissue itself.
The cells of fascia direct the repair process of muscle by secreting more collagen, or "goo" that attracts immune cells to the area of damage. The muscle tissue and especially the surrounding fascia is continually engaged in a process of damage and repair. Fibroblasts are continually repairing the collagen network in which they live, just like a spider repairs its web. Excess collagen and scar tissue can result. This is why some massage therapists will say to their patients, "You're fascia feels tight and thick."
People with fibromyalgia often say their muscles feel "bruised" similar to muscle soreness. One study found that an increase in collagen to the fascia may be the culprit. Comparing specially stained muscle biopsies, researches described a "slight, but significant, increase in collagen surrounding the muscle cells of the fibromyalgia patients."
Chronic activation of the flight-or-flight response may be promoting tension in the fascia of the muscles and lead to tissue damage. Studies show elevated pressures inside the muscles of fibromyalgia may reflect a flight-or-flight nervous system. Muscles and fascia may be constantly tensed in fight-or-flight mode and more prone to injury and damage than just from our usual daily activities.
Fascial dysfunction and inflammation may be the cause of wide-spread muscle pain in fibromyalgia. Excess tension in the fascia due to activation of the fight-or-flight system may lead to excessive tissue damage, similar to over-exercised muscles. Too boot, lack of sleep, a critical time for body tissue repair and remolding, does not provide adequate repair time for strained and damaged fascia.