The skeletal system is made up of bones and joints and provides support, mobility, and protection to various organs in the body. We are born with more than 300 bones. Many of them, such as the skull bones, fuse together and as an adult we have 206 bones. The largest bone in the human body is the femur (thigh bone) and the smallest bones in the human body are the three bones of the middle ear. Maximum bone growth occurs during childhood and puberty, and tapers off as the person approaches 16-18 years of age. While the bones do not grow in size after 18-20 years, they do not remain just as stagnant, hard and inert structures. Continuous metabolic processes called bone remodeling, during which bone is resorbed and formed again occur throughout our life. A major role in this process is played by specialized cells in the skeletal system called osteoblasts which are bone lining cells, and osteoclasts which are bone dissolving cells. Our entire skeleton is renewed every few years and it is estimated that at any time about 20% of an adult bone is undergoing remodeling.