Articular disc of temporomandibular joint: an anatomical and histological study. Functional considerations

The articular disc is an important component of the temporomandibular joint, whose morphology has been studied on autopsy and biopsy materials. The normal posterior attachment of the disc is usually described as having two layers, one upper and one lower. The upper layer consists of elastic fibres, collagen fibres, fat deposits and blood vessels. It is connected posteriorly to the anterior face of the post-glenoid tubercle, the tympanic wall of the temporal bone, the cartilaginous meatus and the parotid gland lining. The lower layer, on the other hand, consists of a compact lamina of non-elastic collagen fibres, attached to the posterior surface of the condyle. Elastic fibres are one of the main constituents of the extracellular matrix of many connective tissues, and they are believed to play a very important role in the normal functions of many tissues such as blood vessels, lungs and dermis. The existence and functional importance of a fibroelastic tissue in the upper layer of the posterior portion of the articular disc has been described in human TMJ and in joints of many animal species. In human TMJ, it is believed that elastic fibres in the posterior and anterior attachment regions may play an important role in the repositioning of the disc during jaw closure. This study presents a review of the current literature on the morphology of elastic fibres in the posterior portion of the joint disc and the role attributed to them during all functions.