Types of muscles
There are three kinds of muscles:
- Skeletal muscle, the muscle attached to bones. They pull on bones to make movements.
- Smooth muscle, for example, the muscle in blood vessels and the bladder
- Cardiac muscle, the muscle of the heart
Muscle action can be classified as being either voluntary or involuntary.
The skeletal muscles move the limbs (arms and legs). They move the jaw up and down so that food can be chewed. Skeletal muscles are the only voluntary muscles. This means they are the only muscle that you can choose to move.
The cardiac muscle is the muscle in the heart. When this muscle contracts (makes itself smaller) it pushes blood through the circulatory system. The cardiac muscle is not voluntary. Animals do not choose for their heart to contract.
The smooth muscles are the other muscles in the body that are involuntary. Smooth muscles are in many places. They are in: