Ball and socket joints are found at the shoulder and the hip. They are able to move in all directions or in all three dimensions. Hinge joints are found at the elbow and knee and they only allow movement in one direction or in only one plane. Hinge joints are formed between two or more bones where the bones can only move along one axis to flex or extend. A pivot joint (trochoid joint, rotary joint, lateral ginglymus) is a type of synovial joint. In pivot joints, the axis of a convex articular surface is parallel to the longitudinal axis of the bone. Pivot and hinge joints can be both considered cylindrical joints. These joints are also called "fixed" or "immovable" joints, because they do not move. These joints have no joint cavity and are connected via fibrous connective tissue. The skull bones are connected by fibrous joints. Sutures are found between bones of the skull.