In hinge joint, the convex surface of one bone fits into the concave surface of another bone. eg, knee, elbow and interphalangeal joints. Pivot joint, one bone is fixed and second articulated, eg, atlas, and axial of skull rotate with axis vertebra. Glinding joints primarily permit side-by-side and back-and-forth gliding movements, eg, intercarpal joints and intertarsal joints. In ball and socket joint, ball of one bone articulates in socket of another bone, eg, head of humerus and glenoid cavity of pectoral girdle.