The skeletal system connects a complex network of bones, cartilage, cartilaginous tissues consisting of 206 bones, including connective tissues. The functions of the skeletal system can be divided into four main types. Firstly, it acts as a body balance which supports the muscles that allow the mobility of the joints and keep them in position, while supporting the body weight. The second function of the system is to protect internal organs, such as the heart, liver, and lungs, from external shocks. The third function is to support the body in making bodily movements possible by using the joints and contraction of muscles attached to the bones. Lastly, the hematogenous function saves calcium, sodium phosphate, magnesium, and ions in the bones, to create blood cells. This function also ensures bone setting when a bone is fractured through the blood vessels in the bones.