[Etiology of eccentric-posterior and centric-anterior displacements of the articular disc].

40 patients with suspected intraarticular soft tissue displacement have been examined clinically and with the aid of electronic recording methods. The disc position has been verified by means of magnetic resonance tomography. Based on these results and on functional as well as anatomic considerations the development of various forms of articular disc displacement is discussed. Within the pathogenetic considerations particular attention must be paid to the role of dysfunctional excessive mouth opening and the loosening of the posterior cranial attachment of the disc on the base of the skull. This attachment is subjected to individual variations. An intact posterior cranial attachment of the articular disc via the superior stratum of the bilaminar zone at the base of the skull may result in an eccentric posterior displacement under existing dysfunctional loads. On the other hand, lack of repositioning forces due to a weak or loosening attachment may favor the development of centric anterior types of displacement.