The appendicular skeleton includes the bones of the upper extremities (arms, forearms, and hands), the pectoral (shoulder) girdle, the pelvic (hip) girdle, and the bones of the lower extremities (thigh, knee, leg, and foot). Its components are aligned along the long axis of the body. The axial skeleton includes the skull, the hyoid bone, the vertebral column (spine, sacrum, and coccyx), the sternum, and the ribs. The skeleton has two parts: the axial skeleton and the appendicular skeleton. Tendons and ligaments are strong bands of fibrous connective tissue that attach muscles to bones, and bones to bones, respectively. Bone also functions as a site for mineral storage and blood cell formation. A joint is a place of union between two or more bones that may be movable or immovable. Bones provide a place for muscles and supporting structures to attach, and, with the movable joints, form a system of levers upon which muscles can act to produce body movements. Because bone is rigid, it gives the body a framework, maintains its shape, and protects vital organs. This system has 206 bones and associated cartilage, tendons, and ligaments.

Vertebrae flat bone