It is called a joint. Joints are also called articulations, they are strong connections that join the bones, teeth, and cartilage of the body to one another. Each joint is specialized in its shape and structural components to control the range of motion between the parts that it connects. Joint is usually formed of fibrous connective tissue and cartilage, they may be grouped according to the type of motion: ball and socket joint, hinge joint, condyloid joint, which permits all forms of angular movement except axial rotation, pivot joint, gliding joint, or saddle joint.