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Articular Disc (articular + disc)
Selected AbstractsAn immunohistochemical study of the triangular fibrocartilage complex of the wrist: regional variations in cartilage phenotypeJOURNAL OF ANATOMY, Issue 1 2007S. Milz Abstract The triangular fibrocartilage complex (TFCC) transmits load from the wrist to the ulna and stabilizes the distal radioulnar joint. Damage to it is a major cause of wrist pain. Although its basic structure is well established, little is known of its molecular composition. We have analysed the immunohistochemical labelling pattern of the extracellular matrix of the articular disc and the meniscal homologue of the TFCC in nine elderly individuals (age range 69,96 years), using a panel of monoclonal antibodies directed against collagens, glycosaminoglycans, proteoglycans and cartilage oligomeric matrix protein (COMP). Although many of the molecules (types I, III and VI collagen, chondroitin 4 sulphate, dermatan sulphate and keratan sulphate, the oversulphated epitope of chondroitin 6 sulphate, versican and COMP) were found in all parts of the TFCC, aggrecan, link protein and type II collagen were restricted to the articular disc and to entheses. They were thus not a feature of the meniscal homologue. The shift in tissue phenotype within the TFCC, from a fibrocartilaginous articular disc to a more fibrous meniscal homologue, correlates with biomechanical data suggesting that the radial region is stiff and subject to considerable stress concentration. The presence of aggrecan, link protein and type II collagen in the articular disc could explain why the TFCC is destroyed in rheumatoid arthritis, given that it has been suggested that autoimmunity to these antigens results in the destruction of articular cartilage. The differential distribution of aggrecan within the TFCC is likely to be reflected by regional differences in water content and mobility on the radial and ulnar side. This needs to be taken into account in the design of improved MRI protocols for visualizing this ulnocarpal complex of the wrist. [source] Stress distribution in the temporomandibular joint affected by anterior disc displacement: a three-dimensional analytic approach with the finite-element methodJOURNAL OF ORAL REHABILITATION, Issue 9 2000Tanaka E. The purpose of this study was to investigate the influences of anterior disc displacement on TMJ loading during maximum clenching by use of finite-element analysis. Based on a young human dry skull, an analytic model of the mandible including the TMJ was developed. In addition to the standard model with normal disc,condyle relation, two models were designed to simulate various degrees of anterior disc displacement. In the standard model, compressive stresses were induced in the anterior, middle and lateral areas on the condyle and glenoid fossa, whereas tensile stresses were observed in the posterior and medial regions. In the models with anterior disc displacement, compressive stresses were recognized in all the areas of TMJ components excluding the bilaminar zone. Shear stresses in the articular disc and bilaminar zone significantly increased in most areas. In conclusion, stress distributions in the TMJ with a normal disc position was substantially different from those with anterior disc displacement, suggesting that the progress in disc displacement may have some association with the nature of stress distributions in the TMJ, in the articular disc in particular. [source] An anatomical study of the muscles that attach to the articular disc of the temporomandibular jointCLINICAL ANATOMY, Issue 8 2009Kosuke Matsunaga Abstract The masticatory muscles are generally described as the muscles that originate from the cranium and insert on the mandible. Some of the masticatory muscles also insert into the articular disc of the temporomandibular joint. Although there are numerous reports of studies on the attachment of the fibers to the disc, most reports discuss only one muscle. We have shown that the masticatory muscles are not simply a group of clearly independent muscles, but that these muscles contain various transitional muscle bundles among the major muscles. From this point of view, we carried out minute dissection of the collective muscles and muscle bundles surrounding the temporomandibular joint. We dissected 40 head halves of 20 Japanese cadavers (10 males, 10 females: average 79.6 yr). After complete removal of the bony elements, the structures surrounding the temporomandibular joint were investigated en-block. In all specimens, the superior surface of the upper head of lateral pterygoid and the midmedial muscle bundle were attached to the disc. In some specimens, the discotemporal bundle, zygomaticomandibularis, and masseter were attached to the anterior surface of the disc. The total vector of these muscles pulls the disc anteriorly. In contrast, the vector of the muscles to the condylar processes of the mandible pulls the mandible medially. From these observations, it seems that the fibers, which attach to the disc act to steady the disc against the masticatory movement. Clin. Anat. 22:932,940, 2009. © 2009 Wiley-Liss, Inc. [source] | ||||||||||