1.SYNOPSIS INTRODUCTION UNIQUENESS OF TMJ ANATOMY OF TMJ ANATOMY OF MASTICATORY MUSCLES. BIOMECHANICS OF TMJ ASSESSMENT AND EVALUATION - Range of movements - Pathway of jaw opening - Maxillary and mandibular midlines - TMJ palpation - Masticatory muscles palpation - Joint sounds - Functional activities DIAGNOSTIC AIDS CONCLUSION

2. INTRODUCTION The Temporomandibular joint is a synovial diarthrodial joint. Also called the ginglymodiarthrodial joint Gingylmus means hinge joint Diarthrodial means the joint space is divided into two separate compartments by means of intra-articular disc. Both hinge action(rotation) Slide action(translation) 3. UNIQUENESS OF THE JOINT Bilateral diarthrosisright and left functionstogether. Articular covered by fibrocartilage instead of hyaline cartilage. This reflects a non-load bearing functional role forTMJ. Covering of the condyle is derives from intramembraneous ossification that normally lacks the endochondral template from which hyaline cartilage is derived. The only joint in human body to have a rigid endpoint of closure that of the teeth making occlusal contact. 4. ANATOMY OF TMJ Superiorly,the mandibular fossa of the temporal bonearticulates with the disc Inferiorly,the disc articulates with the condyle of the mandible. Basic components includes, - mandibular condyle - articular surfaces of temporal bone - joint capsule - synovial membrane - ligaments - intra-articular disc - masticatory muscles 5. ANATOMY 6. JOINT CAPSULE Envelops the articular disc Attached- superiorly to rim of glenoid fossa - inferiorly to neck of condyle anteriorly continous with muscle attachment of lateral pterygoid. - posteriorly,attached to bilaminar zone- 7. SYNOVIAL MEMBRANE Inner surface of the capsule comprises the synovialmembrane. Functions: regulatory secretory phagocytic 8. LIGAMENTS Temporomandibular ligament Stylomandibular ligament Sphenomandibular ligament 9. INTRA-ARTICULAR DISC Disc acts as the shock absorber 4 ZONES: Anterior band Intermediate band Posterior band Bilaminar zone 10. At rest mandibular positon .the condyle is separatedfrom the temporal bone by posterior band As the head of the condyle moves forwards the artiucular eminence.it is seperated from the temporal bone by intermediate zone As anterior movement progresses ,the head of the condyle moves forwards until it is resting on the anterior band The forward movement of the disc is permitted by the loose fibroelastic tissue of bilaminar zone; 11. MASTICATORY MUSCLESMASSTERTEMPORALISMEDIAL PTERYGOIDLATERAL PTERYGOID 12. MASSETER Origin:-Superficial portion-anterior 2/3rd of lower border of zygomatic arch. -Deep portion-medial surface of zygomatic arch Insertion: -Lateral surface of the angle of mandible. Function: - Elevates mandible 13. TEMPORALIS Fan shaped muscle Origin:-Temporal fossa Insertion: -Coronoid process and anterior border of ramus Function: -Elevates and retracts mandible 14. LATERAL PTERYGOID Origin:-Superior head-infratemporal surface of greater wing of sphenoid. -Inferior head- lateral surface of lateral pterygoid plate. Insertion: -superior head-anterior part of capsule and intra-articular disc. -Inferior head-anterior portion of head of the condyle. Function: -depression of the mandible. -protrusion of the mandible. -lateral movements of mandible. 15. MEDIAL PTERYGOID Origin:-Medial surface of lateral pterygoid plate Insertion: -medial surface of the angle of the mandible. Function: -elevation of the mandible. -protrusion and lateral movements. 16. BIOMECHANICS OF TMJ Complex combination activity. Both left and right joints must function together in thecoordination of jaw movements. 3 motions occurs at the mandibleDepression/elevationProtrusion/retrusionLateral excursion 17. ACCESSORY MOTIONS Rotation is the only physiologic movement that can occur between the surfaces. Rotation in the TMJ usually occurs in lower joint space between the head of condyle and the undersurface of intra articular disc Occurs only during the opening of mouth upto 20 to 25 mm Translation or sliding movement occurs in the upper joint space between the upper surface of the disc and inferior surface of glenoid fossa. Occurs when the mouth opens more than 25 mm 18. ROTATION AND TRANSLATION 19. ASSESSMENT AND EVALUATION OF TMJ MEDICAL HISTORYCASE HISTORY MEDICATIONS AND SOCIAL HISTORYHISTORY OF PRESENTING ILLNESS 20. CLINICAL EXAMINATION OBSERVATION:- Opening and closing of the mouth - alignment of the teeth - symmetry of facial structures 21. RANGE OF MOVEMENT Involves examining the interincisal opening andlateral excursions. Normal opening: female-35mm male -42mm Protrusion of mandible: 5mm 22. Lateral movement should be measured from midlineto midline,the patient moving the mandible to their maximum extent,from one side to other. Range of lateral excursion of mandible: 8 to 10mm 23. PATHWAY OF JAW OPENING Mandibular pathway is observed by standing in frontof the patient and asking the patient to repeatedly open and close the mouth. DEVIATION Pain in the mandibular muscles or tmj or Physical obstruction to movement 24. If the pathway is straight joints are acting synchronously. If there is deviation to one side ,then back to midline or alternating first to one side and then across another andagain back to midline temporary obstruction to the movementDisc displacement with reduction 25. If the mandible moves vertically during the first phaseof movement followed by an abrupt deviation Disc displacement without reduction In this case,mouth opens normally until the head ofthe condyle on the affected side encounters the disc in a displaced position Further translation is prevention resulting in marked lateral deviation. 26. MAXILLARY AND MANDIBULAR MIDLINES Patient with straight pathway or transient deviation at maximum opening upper and lower midlines coincide 27. Disc displacement without reduction the midlines would coincide until a point at which the head of the condyle encounters the displaced disc Lateral shift occurs discrepancy in the midlines are noted 28. TMJ PALPATION TMJ PALPATIONLATERAL PALPATIONINTRAAURICULAR PALPATION 29. LATERAL PALPATIONIMMEDIATE PREAURICULAR AREA IS PALPATED BY PRESSING GENTLY OVER IT BOTH AT REST AND DURING MOTION 30. INTRA AURICULAR PALPATION PLACE YOUR LITTLE FINGER IN THE EXTERNAL AUDITOR MEATUS ON ONE SIDE AT A TIME AND APPLYING FORWARD PRESSURE,WHILE ASKING THE PATIENT TO OPEN AND CLOSE MOUTH 31. MASTICATORY MUSCLES PALPATIONMASSETER IT CAN BE PALPATED BIMANUALLY BY PLACING ONE FINGER INTRAORALLY AND ANOTHER EXTERNALLY ON THE CHEEK 32. TEMPORALIS IT CAN BE EXAMINED BY PALPATING ITS ORIGIN EXTRAORALLY.ASK THE PATIENT TO CLENCH THE TEETH AND THE OUTLINE OF THE MUSCLE ORIGIN CAN BE IDENTIFIED.ESPECIALLY THE ANTERIOR FIBRES DIGITAL PALPATION CAN BE PERFORMED BETWEEN THE SUPERIOR AND INFERIOR TEMPORAL LINES. 33. LATERAL PTERYGOID EXTRAORAL: THE PATIENT IS ASKED TO OPEN THE MOUTH.THE EXAMINERS HAND IS PLACED UNDER THE PATIENTS CHIN AND PRESSURE IS APPLIED TO TRY TO CLOSE THE MOUTH WHILE THE PATIENT TRIES TO RESIST 34. INTRA-ORAL: PLACING THE FOREFINGER OR THE LITTLE FINGER,OVER THE BUCCAL AREA OF THE MAXCILLARY THIRD MOLAR REGION AND EXERTING PRESSURE IN A POSTERIOR ,SUPERIOR AND MEDIAL DIRECTION BEHIND MAXILLARY TUBEROSITY. 35. MEDIAL PTERYGOID GENTLY PALPATE THEM ON THE MEDIAL ASPECT OF THE JAW,SIMULTANEOUSLY FROM BOTH INSIDE AND OUTSIDE THE MOUTH 36. CLINCICAL CONSIDERATIONS OF MASTICATORY MUSCLES MASSETER: There is a palpable difference between the affected side and the unaffected side Unaffected side:muscle has a soft rubbery consistency and the margin is less easy to define. Affected side:muscle tends to be bunched up,quite easy to palpate and tenderness may be noted Masseter is found to be tender in patients who clench their teeth. 37. TEMPORALIS: The anterior,more vertical fibres are the main elevator muscles of the jaw and commomly tender on palpation. Posterior fibres,horizontal fibres are less frequently tender because their main function is to retrude the mandible. Temporalis is tender in patients who grind their teeth. 38. LATERAL PTERYGOID: Most commonly involved muscle in MPDS. Unilateral failure of lateral pterygoid to contract results in deviation of mandible towards the affected side on opening. Bilateral failure results in limited opening.loss of protrusion and loss if full lateral deviation. 39. MEDIAL PTERYGOID: It can be palpated only intra-orally Trismus following IANB is due to medial pterygoid muscles Also involved in MPDS. 40. JOINT SOUNDS JOINT SOUNDSCREPITUS CLICKING 41. CLICKS Single explosive noise Felt by the patient but inaudible to examiner Can be felt by palpating the TMJ in the preauricularregion or by intra- auricular palpation Auscultation can be done using stereo-stethoscope. Reciprocal click is seen in disc displacement with reduction. No click is seen in disc displacement without reduction. 42. WHY DO TMJS CLICK? Joint is damaged or overloadedincreased tonicity in the pterygoid muscleDisc is pulled forwardRotational phase of mouth opening occurs normal 43. As the translation phase starts,the head of condyleslides forwards and encounters disc in displacement position. Friction is then built up until the head of thecondylejump past this portion of the disc. Audible release of energy is produced which is theclick. 44. CREPITUS CONTINUOUS GRATING SOUND Indicates degenerative joint disease. It can be auscultated using stereo-stethoscope 45. FUNCTIONAL ACTIVITIES Assess the chewing,swallowing,talking Ask the patient to demonstrate the task or ask forsubjective report. 46. DIAGNOSTIC AIDS MRICT 47. ELECTROMYOGRAPHY Usede to explore the electrical activity of the muscle by recording a electromyogram from a volunteer. The skeletal muscle fibre is innervated by branch of motor axon. Under normal circumstances,a neuronal action potential activates all of the muscle fibres Contraction of muscle takes place. The electrical signal recorded from a contracting muscle is called electromyogram. 48. ELECTROMYOGRAPHY 49. MANDIBULAR TRACKING DEVICES If a jaw tracking devices are used the exact movementof the mandible can be recorded. Drawback: many disorders create deviation in pathways. Because a particular deviation may not be specific for a particular disease. so it has to be used in conjunction with history and examination 50. VIBRATION ANALYSIS Used for diagnosing internal derangement inparticular This technique measures minute vibrations made by the condyle and it translates It is reliable. 51. SONOGRAPHY Used to record and graphically demonstrate jointsounds. Audio amplifying devices or ultrasound echo recordings[doppler ultrasonography] are used. Drawback: cannot distinguish from the normal sound. 52. THERMOGRAPHY Records and graphically illustrates surface skintemperature. Various temperatures are denoted by different colours which produces a map that represent the surface being studied. Normal subjects are said to have bilateral symmetric thermogram. If they are not symmetric suggests a problem. 53. CONCLUSION Nature has blessed us with a marvelously dynamicmasticatory system , allowing us to function and therefore exist. Articulatory system is an important part of the masticatory system of our body. So as a dental care provider to treat the patients of TMDs before knowing the pathology, this is essential to know the normal anatomy and evaluation and assessment of tmj. 54. REFERENCES TEMPOROMANDIBULAR DISORDERS: A PROBLEMBASED APPROACH- ROBIN GRAY. MANAGEMENT OF TEMPOROMANDIBULARDISORDERS OKESON.