Page 14 - Demo

Chapter 112an elevation is seen, forming the posterior articular ridge. This ridge laterally further increases in height, forming the post-glenoid process, which forms the posterior border of the joint.(7)The temporal and condylar component are both separated by an ovalshaped biconcave fibrocartilaginous articular disc. This disc divides the joint in an larger upper and smaller inferior compartment, allowing for a rotational/hinge movement to occur in the inferior compartment, whilst a translational/gliding movement occurs in the upper compartment. The anterior and posterior part of the disc are quite a bit thicker at respectively 2 and 3mm compared to the center, where the disc measures about 1 mm. The posterior part, known as the bilaminar region, has an upper elastin and a lower fibrous layer, separated by connective tissue. The upper layer is connected to the post-glenoid process, preventing anterior displacement of the disc. The inferior layer fuses with the joint capsule below the condyle as to prevent the disc rotating over the condyle. The disc is also fixed to the medial and lateral pole of the condyle, to allow it to move together with the latter. Anteriorly, the disc is fixed to the fibrous capsule of the joint. This fibrous capsule surrounding the whole of the TMJ is called the articular capsule. Anteriorly, an opening in the capsule is seen, allowing the lateral pterygoid muscle (LPM) to pass through and insert itself onto the condyle and the anterior part of the disc. The inside of the capsule is lined with a synovial membrane, thus making the TMJ a synovial joint.(7,8)Besides the capsule, the movements of TMJ are restricted by three main ligaments. The lateral ligament forms a part of the capsule and limits both the forward and posterior translation of the condyle, as well as the maximal lateral movement. The fibers originate from the articular tubercle and insert in the lateral side of the condyle and the condylar neck, as well as into the articular disc. The stylomandibular ligament, which inserts onto the mandibular angle and the posterior border, limits to protrusive movement of the mandible in case of more extreme movements. Lastly, the sphenomandibular ligament remains passive during movement of the lower jaw.(9)Nikolas de Meurechy NW.indd 12 05-06-2024 10:14