What are the four main functions of the skeleton?

The human skeleton serves to protect internal organs, help the human body move, produce blood cells and provide the framework for the rest of the body. During early childhood, the average person has 270 bones. After growth and the process of fusing, most adults end up with 206 bones.

There are five categories of bones in the skeletal system: long bones such as the femur; short bones as in the wrist or ankle; flat bones such as those in the cranium; irregular bones such as vertebrae; sesamoid bones, which form in places where there is considerable stress; and sutural bones, which are very small bones that form between cranial bones.