Thomas Myers

Introduction – extracellular matrix as metamembrane

Despite humans’ biblical and Aristotelian penchant for naming parts, anatomists, however many of the bottomless barrel of terms they know, must admit that the human being is grown organically from a single egg, not assembled like a car from parts. The familiar industrial images that pervade our thinking about the body – the heart is a pump, the lungs are bellows, the brain is a computer, etc. – subtly promote the idea of isolated action and separated systems. We know in our heart of hearts, however, and should remember in our everyday clinical thinking, that our body always does and always has worked together in an unbroken concert from conception on out.

Starting at about fourteen days in embryological development, as cells proliferate and specialize, they create an extracellular matrix (ECM) between them (Moore & Persaud 1999). This delicate web-like intercellular gel provides the immediate environment of most cells, mixing varying proportions of fiber, gluey proteoaminoglycans, and water with diverse and circulating metabolites, cytokines, and mineral salts (Williams 1995). It is this ECM that provides most of the “tissue” bulk in many connective tissues, as the cells alter the ECM to form bone, cartilage, ligaments, aponeuroses, and the rest (Snyder 1975). The ECM grows along with the cells themselves and together they form a single organism connected, joined, and held together by the ECM.

The ECM is intimately connected to cell membranes and through them to the cytoskeleton via hundreds or thousands of binding integrins on the cell surface (Ingber 1998). Forces from outside the cell are transmitted via these adhesive connections to the inner workings of the cell (Ingber 2006a). Thus, we can now understand that each cell, as well as “tasting” its chemical milieu, is “feeling” and responding to its mechanical environment – leading to the relatively new field of “mechanobiology” (Ingber 2006b). Forces also move in the other direction – from the cell to the ECM – in the case of muscular or (myo) fibroblast contraction that gets conveyed through the membrane to the surrounding ECM (Tomasek et al. 2002).

Connective tissue cells are particularly adept at promulgating and maintaining this system of the ECM, which operates under the following design constraints.

To allow trillions of cells to stand up and walk around in an organismic fashion, the ECM must:

The ECM acts as the “metamembrane” for the organism, creating an organismic boundary, restraining and directing movement, protecting delicate tissues, and maintaining the recognizable shape most of us maintain from day to day (Juhan 1987; Varela & Frenk 1987).

Dividing the indivisible

Although the ECM is manifestly one single whole, it is convenient to divide it into three sections:

This last section, which due to the necessity for transmission of strong forces accounts for a significant percentage of the total protein of the body, can again be divided functionally into:

All of the above divisions are imprecise, due to the integrated nature of the ECM; it is sometimes impossible to tell where one section stops and the other begins, and functionally they are all in league with each other. This last division between the outer and inner “bags” within the musculoskeletal system is particularly porous, since these structures have been shown to work in series more often than in parallel (Van der Wal 2009).

Isolating a muscle

After this preamble to holism, the remainder of this chapter will focus on some patterns within this “outer bag” of myofasciae. The traditional view of anatomy that has broadened our knowledge considerably has been gained by a reductionistic parsing of the body, largely with a scalpel. The result is “the muscle” as the predominant label for making named units from the unified soft tissue of this layer. Once a muscle is dissected from its neurovascular fascia, from its overlying areolar layer, and from its neighbors right and left, and the ligaments below, the muscle is analyzed solely in terms of what would happen if the two end points north and south (the so-called proximal and distal attachments) were pulled together in a concentric, isometric, or (with an opposing outside force) eccentric contraction (Williams 1995; Biel 2005; Muscolino 2010).

This isolationist muscle analysis separates one function out of the many and raises it to the level of the function. Most analyses of posture and movement proceed from the idea that individual muscles move bones while individual ligaments stabilize them (Kendall & McCreary 1983). Despite the couple of centuries of kinesiology that has taken this model to its limits, one may question whether the nervous system “thinks” in terms of individual muscles, or whether the muscle, a convenient division for the dissector, is even a distinct physiological unit. Neuromotor units within muscles may be a more useful division (Van der Wal 2009), or larger patterns – our focus for the rest of this chapter – may also tell us something useful about human movement and stability functioning.

More recent thinking, much of which is described in the previous chapter, has focused on functional wholes and interconnected patterns within this outer layer, rather than looking for the muscle or particular fascial structure as the culprit for systemic failure such as injury (or more pointedly, lack of injury repair). The Anatomy Trains Myofascial Meridians is yet another of these maps, owing much to the work that has come before, from Raymond Dart through Tittel, Mezières, Hoepke, and others, yet at the same time this system has some unique features (Hoepke 1936; Dart 1950).