Bones provide the body with structure and support. In this chapter you will learn about the bones of the body, their structure, and how the joints of the body work. The skeletal system is composed of 206 bones as well as joints and related connective tissues. The skeleton has two major divisions-the axial skeleton and the appendicular skeleton. The axial skeleton contains 80 bones. It includes the bones of the skull, vertebral column, and rib cage. It functions to support the head, neck, and trunk and protects the brain, spinal cord, and the organs in the thorax. The hyoid bone, which anchors the tongue, is also included in the axial skeleton. The appendicular skeleton includes the bones of the arms, the legs, the pectoral girdle and the pelvic girdle. The pectoral girdle attaches the arms to the axial skeleton, and the pelvic girdle attaches the legs to the axial skeleton (Figure 25-1).