The Muscular System NEW site Muscles are the part of our body that allow us to move. They are made up of special tissues that can lengthen and shorten, resulting in movement. The muscles are attached to bones by stretchy tissue called tendons. When the muscles lengthen or shorten, they pull on the tendons which pull on the bones and cause our limbs to move.
Muscles band together to form muscle groups which work together.
Voluntary muscles, such as your arms and legs can be controlled by your thoughts. All this muscle action is controlled by your brain, which sends and receives signals through your nervous system. Muscle actions can be voluntary or involuntary. Involuntary muscles, such as the heart, diaphragm and intestines, are automatically controlled by the brain. You don't have to think about making them work.