4
CHAPTER
MUSCULAR SYSTEM
I
f the job of the skeletal system is to transfer weight and force by way of the ligaments
through the bones in any arrangement the joints allow, then the task of the muscular
system is to move the bones into place so that the bones can do their job. Muscles create
movement, joints enable movement, and connective tissue translates movement from tissue
to tissue. Bones absorb and transmit movement, and nerves coordinate and organize the
whole gorgeous dance.
The muscles work together as a matrix of potential movement choices. This matrix affects
every articulation in the body. Muscles do not work in isolation, and a single muscle never
works without support and modulation from other muscles. Each muscle has an effect on
every other muscle, whether they are nearby or far away.
Historically, muscles have been presented in a simplistic, linear paradigm, which leads
to misconceptions such as:
- Muscles work as discrete units.
- For every body, the same muscles always
create the same joint action. - The more tone a muscle has, the better
it can function. - Muscles always relate to each other in
the same way. - There is a correct set of muscles for
executing any movement.
To understand why these assumptions are
incorrect, it is necessary to examine the basic
anatomy of muscles.
Basic Muscle anatoMY
What we usually think of as a working muscle is
actually an organ made up of at least four dif-
ferent tissues: muscle tissue, connective tissue,
nerves, and blood vessels (fi gure 4.1, page
56). The muscle tissue itself has the ability to
contract and create movement. The connective
tissue communicates the power of that contrac-
tion to whatever the muscle is connected to,
such as bones, organs, or skin. The nerves tell
the muscle when to fi re, for how long, and at
what intensity, and the blood vessels provide
the nourishment that allows the muscle tissue
to be active.
Muscles are divided into three basic types:
skeletal muscle, cardiac muscle, and smooth
muscle.
Try this experiment: Lie down on
your back. Open your arms to the
sides at a comfortable level, palms
facing up. Your legs can be bent or
extended. Take some time to settle
into this position. Then, starting with
a very small movement, begin to
wiggle your fi ngers.
Can you feel how the muscles in your
forearms are activated as you wiggle
your fi ngers? How about the muscles
in your upper arms? The muscles in
your shoulders and upper back? Can
you feel the muscles around your
spine respond to the wiggling of your
fi ngers? How about the muscles in
your jaw? Can you follow the move-
ment to your feet?
If it feels as though the movement
doesn’t travel anywhere, see if you
can feel where it stops. Are you hold-
ing on to anything in your muscles
that you don’t need to? What can
you release so that the movement can
travel with ease through the body?