Joints can be classified into four mam types. A hinge joint allows movemmt in one direction only such as the movement when a door opens. It can be found in the elbows and the joint of the fingers and toes. The second type is the pivot joint which allows rotation. You can turn your hand up or down by means of the radius pivots at the elbow. Next is the ball-and-socket joint in which the spherical head of one bone lodges in the spherical cavity of another. In the shoulder
joint the upper arm bone fits into the socket of the shoulder blade. And the last one is called the
gliding joints, They exist between wrist bones. where one bone slides slightly over the nat suMce of
the other. They allow a wide range of mostly sideways movements as well as movements in one
direction.