The skeletal system is also affected by degenerative disorders such as osteoporosis. A fracture is any type of break in a bone. Fractures can be either compound or simple. A compound fracture is one in which the broken end of the bone protrudes through the skin. A simple fracture is one in which the broken bone does not protrude. Hairline fracture is incomplete, and the two parts of the bone do not separate. Transverse fracture is completely across the bone, may result from a sharp, direct blow of from stress caused by prolonged running on an already damaged bone. Comminuted fracture is when the bone shatters into more than two pieces, usually as a result of severe force.
.
Certain muscles in your body are always at work. Even when you sleep, muscle help you breathe, make your heart beat, and move food through your digestive system. These involuntary processes happen without our consciously controlling them. At other times, such as when you play the piano or a video game, make a dash toward first base, or throw a ball, you are using muscles that are under conscious, or voluntary control. .
.
A muscle is made up of hundreds of long cells called fibers. Major Muscles in the body are made of hundreds of bundles of these fibers. Muscles work by means of two complementary, or opposing, actions. These are contraction, the shortening of a muscle, and extension, the stretching of a muscle. Muscle contraction is triggered by nerve impulses. Some nerves provide impulses for many muscle fibers, especially to large muscles such as your eyes, a single nerve may provide impulses to only two or three muscle fibers. There are three types of muscle tissues, smooth muscles, skeletal muscles and cardiac muscles. Smooth muscles act on the lining of passageways and internal organs. Skeletal muscles are attached to the bone and cause body movements. Cardiac Muscle is a type of striated muscle that forms the wall of the heart.