The nucleus within the vertebral disk is like a piece of candy that has a liquid center. If you squeeze the candy, the liquid center is forced to move in the opposite direction away from the pressure....

The nucleus within the vertebral disk is like a piece of candy that has a liquid center. If you squeeze the candy, the liquid center is forced to move in the opposite direction away from the pressure. If you pull on the top and bottom of the piece of candy, the liquid center will move back toward the center. Traction can effect movement of the nucleus away from the nerve root, thus decreasing pressure.