The skeletal system provides structure and movement to the body. It works with muscles as part of the musculoskeletal system. There are different types of bones including long, short, irregular, flat, compact and spongy bones. Joints allow bones to move and come in immovable, slightly movable, and freely movable varieties like hinge, pivot, and ball and socket joints. Ligaments connect bones at joints while cartilage cushions joints and can form cartilage bones in infants.