SCIENCE OF YIN YOGA 55Gray’s Anatomy (1995, 80) defines the extracellular matrix as the following:The term extracellular matrix (ECM) is applied to the sum total of
extracellular substance within the connective tissue. Essentially it
consists of a system of insoluble protein fi brils and soluble com-
plexes composed of carbohydrate polymers linked to protein mol-
ecules (i.e., they are proteoglycans) which bind water. Mechanically,
the ECM has evolved to distribute the stresses of movement and
gravity while at the same time maintaining the shape of the different
components of the body. It also provides the physio-chemical envi-
ronment of the cells imbedded in it, forming a framework to which
they adhere and on which they can move, maintaining an appropri-
ate porous, hydrated, ionic milieu, through which metabolites and
nutrients can diffuse freely.As you can see, the connective tissues are vast and complex. Their roles
and functions are unparalleled. Included in the category of connective tissues
are tendons, ligaments, bones, cartilage, joints, and fascia.
Tendons
A tendon is a tough band of dense, white,
fibrous connective tissue that joins a
muscle to a bone (see figure 4.2). Although
different structures of the body are often
depicted as separate in anatomy books,
the reality is that there is a gradual con-
tinuum from muscle, to tendon, and then
eventually into bone. Tendons function
to transmit forces and withstand tension.
Tendons are made of collagen fibers that
ensure strength and flexibility and provide
a natural resistance to being overstretched.
A stretch of 4 percent is the limit of a
tendon’s flexibility. If the tendon experi-
ences a larger stretch, the nervous system
sends a warning signal to quickly relax
the muscle. A stretch beyond this capacity
could result in permanent damage to the
tendon. The Achilles tendon, which con-
nects the calf muscle to the heel bone, is
a well-known example of a tendon.
E7122/Eliot/F04.02/590015/mh-R1Achilles
tendonFIGURE 4.2 Tendon.