Skeletal system is made up of your bones, ligaments, and tendons. It determines the shape and symmetry of the body; acts as a protective device for your organs; acts as a firm base for the attachments of muscles (without bones, your muscles would not function properly); and the marrow tissues in the cavity of the bones produces red cells and some white cells, required in your blood.
Human have an endoskeleton, meaning that they are located inside the body. It consists of about 200 bones. The number of bones varies, because some bones fuse at different periods of time. Most bones are hollow with marrow cells inside. Ligaments connect bones to bones, and tendons connect bones to muscles.
Axial Skeleton and Appendicular skeleton:
The skeleton are divided into appendicular skeleton (bones of arms and legs or "appendage", and girdler, which attach them to the rest of the body), and axial skeleton (skull, backbone or "vertebrae," ribs and breast bone, or "sternum").
The skull is made up of number of bones fused together. The backbone is composed of 33 separate different size and shaped vertebrae, and each of them are composed of centrum (base portion), and neural arch (surrounds and protects spinal cord.) 12 pairs of flat bones make up the rib basket. Its function is to support the chest wall, and prevents it from collapsing, when the diaphragm contracts.
Appendicular skeleton are made up of pelvic girdles (consists of 3 fused hipbones), pectoral girdles (consists of 2 collar bones - "clavicles"), and 2 scapulas (shoulder blades.)
There are 4 types of joints, the part of junction between 2 bones.
Ball and socket allows freedom of movement in several directions. It can be found between humerus & scapula; and femur & hipbone.
Hinge joint allows movements in a single plane. An example of this joint can be found in your knee.
Pivot joining allows freedom of movement of somewhat between ball and socket & hinge joining. It can be found in your wrists and ankles.
Joints of the skull are extremely strong and immovable.
Smooth and slippery cartilage covers the ends of the bones to reduce friction during the movement.