Bones of the skeleton move when muscles contract and pull on the tendons which attach the muscles to the bones.
Maintenance of posture
Contraction of specific skeletal muscles stabilizes joints and helps maintain the bodys posture or position. Postural muscles contract continuously when a person is awake to prevent collapse. (When a person falls asleep in, say, a lecture hall, the head droops forward and the mouth rolls open).
Energy is required for muscle tissue contraction, and heat is always produced as a waste product of this energy usage. When you exercise, you feel warmer; the heat you feel is produced by your working muscles. Likewise, you shiver when you are cold because your muscles are contracting and relaxing to produce heat.
Storage and movement of materials
Sphincters (circular muscle bands) contract at orifices (openings) of the gastrointestinal and urinary tracts. These sphincters may be voluntarily closed or open (to store material within an organ).
Sheets of muscle protect the organs and support their weight within the abdominopelvic cavity.