Musculoskeletal system includes the following structures: bones, joints, muscles, tendons, ligaments, and cartilage. These structures are combined to support body's activities.
Bones contain calcium, phosphorus, sodium, protein collagen and minerals. Sufficient calcium is important, so that bones can support body weight. Muscles has three types: skeletal muscle, smooth muscle and cardiac muscle.
Skeletal muscles, also called striated muscles, are mostly in the arms, legs, abdomen, neck, face, and chest. Smooth muscle is often located in the stomach wall, intestine wall, or blood vessel wall. Cardiac muscle is located in the heart.