Joints

A joint is a connection in two or more bones. There are four main different kinds of joints: hinge joints, fixed joints, pivot joints, and ball-and-socket joints. Hinge joints, such as the knee, allow a forward and backward swinging movement, like a door on hinges. Fixed joints, like the bones between the skull, allow no movement. Pivot joints give a rotating motion, like the pivoting movement of the neck joints. Ball-and-socket joints allow the most free movement. They are made of the rounded end of one bone and the hollow end of another. They allow side to side movement and rotating movement. some examples are the hips and shoulder. Some joints, however, are allowed more movement by the way they are arranged. All joints are protected from wearing away by cartilage. Cartilage also allows smooth movement of joints. All of these parts work together to create a movement and a smooth one.