The major functions of the muscular system are:

1. Body movement due to the contraction of skeletal muscles

2. Maintenance of posture also due to skeletal muscles

3. Respiration due to movements of the muscles of the thorax

4. Production of body heat, which is necessary for the maintenance of body temperature, as a byproduct of muscle contraction

5. Communication, such as speaking and writing, which involve skeletal muscles

6. Constriction of organs and vessels, especially smoother muscles that can move solids and liquids in the digestive tract and other secretions, including urine, from organs

7. Heart beat caused by the contraction of cardiac muscle that propels blood to all parts of the body