Fascia

Scientific basis

The nomenclature proposed by the Fascia Nomenclature Committee distinguishes "a fascia," an identifiable connective structure, from the "fascial system," a broader notion describing connective tissues in functional continuity. These two terms have different scopes, and the terminology is still debated.

Beyond nomenclature, two properties shed light on why fascia is not a mere filler tissue. First, gliding between adjacent fascial layers depends on a layer of loose connective tissue rich in hyaluronic acid; a study on cadaveric tissue (n=3) and by ultrasound in living subjects (n=22) proposes that a change in the viscosity of this hyaluronic acid reduces this gliding, a mechanism put forward, not demonstrated as causal, for some myofascial pain. Second, the thoracolumbar fascia is richly innervated by sensory fibers, including free nerve endings with presumed nociceptive activity concentrated in its superficial layers; this finding, established in rats and preliminary in humans, indicates that fascia is not a passive tissue from a sensory standpoint.

Blue Portance / SBNFA™ reading

Blue Portance favors a functional reading focused on the relationships between tissues, tissue gliding and stress transmission. This reading rests on the documented existence of an inter-fascial gliding mechanism and of a sensory innervation of fascia; it does not infer from them that a given seating configuration measurably changes the viscosity of hyaluronic acid or the activity of these nerve fibers in a seated person. This choice of framework does not turn every functional hypothesis of SBNFA™ into anatomical consensus.

Contribution to the analysis of sitting

This reading invites us to examine the positions, contacts and adjustments likely to change the mechanical stress applied to tissues, particularly those that could durably restrict tissue gliding in one area. It does not allow the conclusion that a seat restores measured fascial gliding, changes hyaluronic acid or treats pain of fascial origin.

Not to be confused with

"a fascia" as an anatomical structure and the "fascial system" as a broader functional notion; these two definitions are complementary in the cited nomenclature.

Sources and scope

• Schleip et al. (2019): nomenclature process and distinction between "a fascia" and "fascial system"
• Stecco et al. (2011): anatomical study of fascial layers and hyaluronan
• Tesarz et al. (2011): sensory innervation of the thoracolumbar fascia in rats and humans