The human body has three types of muscle tissue: cardiac, smooth and skeletal. Cardiac muscle, as its name implies, is the muscle of the heart. Smooth muscle is the muscle that lines the walls of the organs of the body, such as the intestinal tract. And skeletal muscle, which you are probably the most familiar with, is the muscle attached to the skeleton.
Skeletal Muscle
The musculoskeletal system of the human body consists of bones, joints, muscles and tendons that allow a variety of movements. There are hundreds of skeletal muscles in the body. Each skeletal muscle contains muscle cells, connective tissue, nerves and blood vessels. Each one is attached at both ends to a bone by connective tissue. Virtually all body movements involve multiple skeletal muscles.
Control
Skeletal muscle is the only type of muscle that you can voluntarily manipulate. While the brain controls the movement, you are aware of the movements. The brain also controls smooth and cardiac muscle; however, it does it in response to the needs of your body. They are therefore considered involuntary muscles.
Function
Skeletal muscle has several basic functions. The most obvious is its ability to enable you to move freely. It is also instrumental in breathing, postural support, heat and energy production.
Actions
There are two basic types of skeletal muscles. Flexors are muscles that decrease joint angles. Examples include the biceps and hip flexors. Extensors are the muscles that increase or open up a joint angle. Some examples of extensors include the triceps and the quadriceps.
Types
Skeletal muscles are composed of fibers that can be characterized as either slow twitch or fast twitch fibers. While some muscle groups are known as either fast or slow twitch fibers, they all contain a mixture of fast and slow. The basic difference between the two are in performance. Slow twitch muscle fibers contract and relax at a slower rate and they can perform for longer periods of time. Slow twitch muscle fibers are those utilized in activities such as long distance running or cycling. Fast twitch fibers are used for more explosive, short bursts of activities. However, fast twitch fibers fatigue more quickly than slow-twitch.
