The skeletal system is composed of bone and cartilage and can be divided into the axial skeleton and appendicular skeleton. The axial skeleton includes the bones of the skull, vertebral column, and thorax. It supports the structures of the head, neck, and trunk and protects the brain, spinal cord, and thoracic organs. The appendicular skeleton comprises the bones of the upper and lower limbs, which attach to the axial skeleton and allow for movement. Bones are lightweight but strong and form the framework of the body, protecting internal organs and allowing for movement.