Clinical Aspects and Cellular Mechanisms of Fascia, their Interactions, and Importance in Medicine
Authors: Findley Thomas 
Published: June 2021

The fascial system is a 3D continuum of soft, collagen‐containing, loose and dense fibrous connective tissues, widely including adipose tissue, adventitiae and neurovascular sheaths, aponeuroses, deep and superficial fasciae, epineurium, membranes, joint capsules, ligaments, meninges, myofascial expansions, periostea, retinaculae, septa, tendons, visceral fasciae, and all the intramuscular and intermuscular connective tissues including endo‐/peri‐/epimysium. These muscle layers may seem distinct in 2D sections, but the borders are somewhat arbitrary when viewed as an extensive 3 D network, with connective tissue fibers extending both along and across muscle fibers. The fascial system interpenetrates and surrounds all organs, muscles, bones and nerve fibers, endowing the body with a functional structure, and providing an environment that enables all body systems to operate in an integrated manner. Fascia is traditionally named according to the discrete anatomic structure that it surrounds which obscures its continuity and distinct layers.

Fascial tissue provides a structural framework, continuously adapting and transmitting mechanical and chemical signals to differentiate tissue. The continuum of fascia throughout the body allows it to serve as a body‐wide mechanosensitive signaling system. The extracellular matrix plays an essential role in the development of skeletal musculature in the embryo. Fascia is a composite material of collagen fibers and matrix. In outer layers of the extremities and neck, fibers are found in parallel directions oriented at 55 degrees to the layer underneath, similar to a garden hose, which resists pressure and remains flexible. In other layers, collagen fibers are less regular and may have a wavy or helical structure. Fascia may also vary in proportions of collagen type I, III, IV and V and in rate of turnover. Fascial structure has functional implications. For example, when one muscle contracts against a thick, resistant fascia layer, the compartment pressure increases, and this pumps blood and lymphatic fluid against gravity and raises the contractile efficiency of other muscles in the same compartment. A fiber connects a muscle to the nitric oxide receptor of its arteriole, which is pulled open during contraction to increase blood flow. Thoracolumbar fascia balances abdominal and spinal muscle tension.

Fascia is gaining interest from researchers, physicians and many types of therapists. Manual therapy techniques treat the fascial layers by altering density, tonus, viscosity, and the arrangement of fascia. Manual stimulation of sensory nerve endings may lead to tonus changes in muscle. The fascial system is now being recognized in the etiology of pain and proprioception. Fascia research can help understand aspects of musculoskeletal problems such as myofascial trigger points, low back pain, and fibromyalgia. Connective tissue influences the normal or pathological processes in a wide variety of organ systems e.g. intramuscular connective tissue architecture changes after immobilization of an extremity.

The mechanical interactions among muscle, tendon and fascia in humans developed over many thousands of years and allow us to adapt to a wide range of activities. We are just beginning to understand these enough to develop specific fascial exercises and activities.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.