||The skeleton performs numerous vital functions. It shelters and supports softer tissues, and provides mechanical rigidity. Its surfaces form the attachment sites and lever arms for muscles, tendons, and ligaments that posture and move the body parts. It is our storehouse for mineral salts, particularly calcium, and parts of the skeleton are the source of red blood cells. There are officially 206 bones in the adult human skeleton, but the unpredictable supernumerary bones, especially those in the hands and feet, increase that number.