The skeleton is a very important part of our body. It protects delicate inner and it enables us to move. The bones have such as elbows and knees so that we can bend our . Without our skeleton, we would not be able to stand upright or walk. The brain is protected by the . From the brain, a nerve called the cord runs down the backbone. The backbone is split into segments called which help us bend our back. Our protect our heart and lungs and the protects the intestine and reproductive organs. Muscles are joined to the bones by . The brain sends signals to the muscles through the nervous system. These signals make the muscles or relax and this pulls the bones up or down when we want to move.