Figure 1-4. Diagram of a bone.
This system includes over 350 muscles. These muscles are made up of muscle
tissue. They constitute 40 to 50 percent of the body's weight. The muscular system
moves and propels the body and the contents of the hollow organs. It also keeps the
body erect and produces body heat. Three types of muscles are found in the body.
a. Striated Muscle. This muscle produces bodily movement. Skeletal muscle
is also called voluntary muscle since it can be consciously controlled. Figures 1-5 and
1-6 illustrate some skeletal muscles.
b. Smooth Muscle. This muscle is found in various visceral organs where
continuous automatic functions are necessary. Smooth muscle is also called
involuntary muscle since it contracts without conscious direction by the individual. For
example, the unconscious contraction of the intestinal muscle moves food through the