A Journey Into Yin Yoga

SCIENCE OF YIN YOGA 57

lighter and spongy. Even deeper is the medullary cavity, which houses bone
marrow. There are two types of bone marrow: yellow, which is made up of
fat cells, and red, consisting of hematopoietic tissue, which is where the red
blood cells, platelets, and white blood cells are made.

Cartilage

Cartilage is a firm but flexible tissue
made predominantly of protein
fibers (see figure 4.5). It is less com-
plex than bone tissue, having fewer
cells and minimal or no blood flow.
It has a smooth, elastic quality. Two
types of cartilage in the skeletal
system are hyaline and fibrocarti-
lage. Hyaline cartilage composes the
septum of your nose and is the major
component of the joints, especially
synovial joints. In the fetus, hyaline
cartilage helps in the construction of
new bone. This bendy bone makes
the baby a natural “yinster” in the
womb. Fibrocartilage is a spongy tissue that serves as a shock absorber in
the spine and pelvis. Cartilage protects the end of long bones at the joints.
Chondrocytes are the cells that build new cartilage.

Joints

A joint is where two bones join together and link the skeletal system as a
whole. Working in tandem with skeletal muscles, the function of the joints
is to provide movement and bear weight in the body. The following are the
three types of joints.

• Fibrous—Dense connective tissue that is rich in collagen fibers joins
  two bones in this type of joint (see figure 4.6a). These joints are also
  called fixed joints because they don’t move. An example of this is
  where the radius and ulna bones meet in the lower arm.


• Cartilaginous—Cartilage joins two bones in this type of joint (see
  figure 4.6b). There is more movement in this type of joint than a
  fibrous joint, but less than synovial. An example of this are the discs
  in the spine.


• Synovial—A cavity exists between two bones in this type of joint. The
  cavity is filled with synovial fluid and dense connective tissue (see
  figure 4.6c). This type of joint produces the most movement.

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Cartilage

of the ribs

FIGURE 4.5 Cartilage.