A histologic study of retrodiscal tissues of the human temporomandibular joint in the open and closed position.

Specialized roles for the different components of the retrodiscal tissues have been previously postulated. This study compared the histologic features of the retrodiscal tissues of temporomandibular joints, taken from human cadavers, in the open and closed position; it was concluded that the primary role of these components was to provide a volumetric compensatory mechanism for pressure equilibration. This mechanism was still active in joints that demonstrated disc displacement and degenerative changes. Elastin was found in the upper and lower strata of the retrodiscal tissues, as well as in the central zone. The concept of an elastic upper stratum that has a recoil mechanism to control disc movement was not supported by this study, as the upper stratum was folded on itself in the closed position and only became stretched near maximal opening.