Your TMJ is unique in that your mandible (lower jaw bone) has a joint on either side, so one affects the other. Each TMJ (jaw joint) is a type of ball-and-socket joint, similar to what you have in your hip. This design allows your TMJ to move up and down, side to side, and in a variety of different directions — all of which are essential for being able to fully chew your food in preparation for the digestion process.