Which structure gives the tooth MOVEMENT (periodontal movement)?

Sharpey's fibers are the terminal portions of principal fibers of the PDL embedded in cementum and alveolar bone. They transmit forces and give the tooth its resilient 'movement' within the socket. The PDL principal fibers (Sharpey's fibers) function as a hammock/suspension system. The alveolar bone and cementum are rigid; ground substance provides support but not movement.