The movements of the mandible which create the multitude of tooth contacting positions are activated by the muscles of mastication but controlled by the temporomandibular joints. The muscles place the mandible in a great variety of positions, but the paths of motion to these positions are determined by the joints. The prosthetic relations of the joint are those actions of the joint which enter into, or create problems of, tooth restorations. They are not concerned primarily with the anatomy of the joint, but rather with the way that anatomy enters into functional relations of the teeth, either natural teeth or their artificial counterparts.