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Temporomandibular Joint (TMJ) This joint represents the complex "articulation" between the moveable mandible and the base of the skull. Specific articulation movements actually take place in 2 regions: 1) between the mandibular and maxillary dentition - termed interjaw dental occlusion 2) between the head of the mandibular condyle and glenoid fossa of temporal bone. Condylar process lined by fibrous tissues, primarily hyaline cartilage this is the primary growth center of the mandible • damage leads to facial maldevelopment, including both the mandible and the maxilla Coronoid process insertion for portions of temporalis and masseter The TMJ is a condylar synovial type of joint. The specific definition of this joint type describes two opposing surfaces both of which display two convex and two concave surfaces. The movements and structure of the TMJ should always be considered as a pair i.e. one condyle is the left TMJ while the other condyle is the right TMJ. The articular surfaces are covered by cartilage. In addition an articular disc divides the joint into two. Around the joint is the articular capsule which, in certain regions is thickened to form "ligaments" which are given specific names. 5 ligaments assoc. with TMJ 3 functional, 2 accessory functional: collateral (discal) ligaments capsular ligament temporomandibular ligament accessory: sphenomandibular stylomandibular 1) Temporomandibular ligament. 2) Sphenomandibular ligament. 3) Stylomandibular ligament. Note that, due to the disc the joint is divided into superior and inferior compartments. Movements of mandible 1.Protraction: While maintaining the teeth in the occlusal position - slide the mandible anteriorly. 2) Retruction: Slide the mandible posteriorly after protrusion. Confirm that the condyle moves up as it reaches the fossa. 3) Depression: Note that 2 phases of depression occur. An initial opening and rotation followed by a gliding. 4) Elevation: The opposite to depression. 5) Lateral excursions: This movement occurs when the teeth slide from the centic position to the right or left, while maintaining occlusal contact, then back to the centric position. Diseases of theTMJ The TMJ is susceptible to all diseases that affect other joints 1. congenital anomalies 2. ankylosis 3. arthritis 4. trauma 5. dislocations 6. neoplasms Disorders of theTMJ Muscle Disorders (Extracapsular) TMJ Disorders (Intracapsular) 1.Inflammatory conditions 2.Internal derangement Disc sticking TMJ dislocation Disc displacement with reduction Disc displacement without reduction Diagnosis of myofacial pain The temporomandibular joint and preauricular area is tender to palpation, manipulation, and/or vertical loading. Patient generally reports pain with mandibular function. Myofascial Pain Disorders Categories: 1. Myositis 2. Muscle Spasm 3. Contracture 4. Hysterical trismus 5. Fibromyalgia TMJ Dislocation An anatomical relationship in which the lateral pterygoid muscle advances the condyle anterior and superior to the crest of the articular eminence, and due to muscle spasm in the elevator muscles and/or specific anatomical relationships, the patient is unable to return to a closed position. Acute dislocation treatment is reduction under anesthesia Chronic dislocation usually secondary to abnormally lax tendons Treatment: sclerosing agents, capsulorraphy, myotomy of lateral pterygoid Treatment of Mandibular Dislocation Therapy for Temporomandibular Disorders Occlusal appliances - Stabilization splints Fills in interocclusal space if bite is unsupported or unstable (e.g. posterior open bites ) Disengages occlusal habits (can be a full occlusal coverage appliance, or a partial occlusal coverage applicable but this should be worn only short term to avoid inducing an occlusal change) May interrupt bruxing habits May reduce direct joint loading May indirectly reduce joint loading by reducing jaw muscle hyperfunction / clenching Surgery of TMJ Less than 1% of people with TMJ symptoms will require surgery Five requirements for surgery Kinds of sugery Disc Repair Menisectomy Menisectomy with implantation Arthroscopy Radiology MRI is best technique for joint space pathology CT is best technique for bony pathology Plain films with arthrography sometimes useful, although largely replaced by MRI and CT Arthroscopy is also diagnostic