The skeletal system helps support the body, protects internal organs, allows movement, and stores minerals. There are several types of joints including immovable, slightly movable, and freely movable joints. Bone is surrounded by periosteum and connected by ligaments, and contains bone marrow and Haversian canals. There are three types of muscle tissues: skeletal, smooth, and cardiac. Skeletal muscles are voluntary and control movement. Smooth muscles are involuntary and control organs. Cardiac muscles are only found in the heart. Muscles contract through the interaction of the myosin and actin filaments when calcium ions are released following the transmission of an impulse from a motor neuron. Tendons connect muscles to bones so that