sbard notes - 6

8/6/2019 Sbard Notes - 6

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The TemporomandibularThe TemporomandibularThe TemporomandibularThe TemporomandibularThe TemporomandibularThe TemporomandibularThe TemporomandibularThe TemporomandibularJointJointJointJointJointJointJointJoint

Prof . Rita KhounganianProf . Rita KhounganianProf . Rita KhounganianProf . Rita KhounganianProf . Rita KhounganianProf . Rita KhounganianProf . Rita KhounganianProf . Rita Khounganian

CLASSIFICATION OF JOINTSCLASSIFICATION OF JOINTSCLASSIFICATION OF JOINTSCLASSIFICATION OF JOINTSCLASSIFICATION OF JOINTSCLASSIFICATION OF JOINTSCLASSIFICATION OF JOINTSCLASSIFICATION OF JOINTS

1.1. Fibrous jointsFibrous joints::-- cranial suturescranial sutures-- tooth sockettooth socket

22.. CartilaginousCartilaginous jointsjoints::PermitPermit littlelittle ifif anyanymovementmovement betweenbetween thethebonesbones involvedinvolved

PrimaryPrimary cartilaginouscartilaginous::costochondralcostochondral jointjoint

SecondarySecondary cartilaginouscartilaginous::pubicpubic symphisissymphisis

33.. SynovialSynovial jointjoint::TMJTMJ


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Anatomy ofAnatomy ofAnatomy ofAnatomy ofAnatomy ofAnatomy ofAnatomy ofAnatomy ofthe TMJthe TMJthe TMJthe TMJthe TMJthe TMJthe TMJthe TMJ

BASIC COMPONENTS OF TMJBASIC COMPONENTS OF TMJ

The right and leftThe right and leftcondylar heads of thecondylar heads of themandiblemandible

The articulating surfacesThe articulating surfacesof the temporal boneof the temporal bone(glenoid fossa and(glenoid fossa andarticular eminence )articular eminence )

The articulating discThe articulating disc(meniscus)(meniscus)

The articulating capsule,The articulating capsule,synovial membranesynovial membrane andandsupportive ligamentssupportive ligaments

ANTERIOR


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The Articular Space isThe Articular Space is

divided into 2 Compartmentsdivided into 2 Compartments

The 2 compartmentsThe 2 compartmentsdiffer in Actiondiffer in Action

UPPER COMPARTMENT :UPPER COMPARTMENT : (TEMPORODISCAL)(TEMPORODISCAL)

TranslatoryTranslatory Gliding actionGliding action being the largerbeing the largerbetween disc and temporal bonebetween disc and temporal bone

LOWER COMPARTMENT :LOWER COMPARTMENT : (CONDYLODISCAL(CONDYLODISCAL))

RotationalRotational Hinge actionHinge action between under surfacebetween under surfaceof the disc and the rotating surface of the headof the disc and the rotating surface of the headof the condyleof the condyle


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Young CondyleYoung Condyle

Glenoid FossaGlenoid Fossaand Articular Tubercleand Articular Tubercle

CondylarCondylarHeadHead

DiscDisc


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AnteriorAnterior

CondyleCondyle

Very thinVery thincortexcortex

MedullaryMedullary trabeculaetrabeculae

Marrow tissueMarrow tissue

[hematopoietic even in adults][hematopoietic even in adults]

HISTOLOGY OFHISTOLOGY OFHISTOLOGY OFHISTOLOGY OFHISTOLOGY OFHISTOLOGY OFHISTOLOGY OFHISTOLOGY OF ADULTADULT CONDYLECONDYLECONDYLECONDYLECONDYLECONDYLECONDYLECONDYLE

Large marrow spaces areLarge marrow spaces arefound in the cancellousfound in the cancellousbone but decrease by agebone but decrease by agedue to marked thickening ofdue to marked thickening ofthe trabeculaethe trabeculae

The red marrow is cellularThe red marrow is cellularthen later replaced by fattythen later replaced by fattymarrow in old individualsmarrow in old individuals


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Covering of the Bones of the JointCovering of the Bones of the JointCovering of the Bones of the JointCovering of the Bones of the JointCovering of the Bones of the JointCovering of the Bones of the JointCovering of the Bones of the JointCovering of the Bones of the Joint

DenseDense avascularavascular fibrous CTfibrous CT

Consisting largely of bundlesConsisting largely of bundlesof collagen fibersof collagen fibers

Very occasionalVery occasional elastic fibreselastic fibresinterspersed through theinterspersed through thecollagencollagen

Fibroblasts are situatedFibroblasts are situated

between the fiber bundlesbetween the fiber bundles

Histology of the Articular DiscHistology of the Articular DiscHistology of the Articular DiscHistology of the Articular DiscHistology of the Articular DiscHistology of the Articular DiscHistology of the Articular DiscHistology of the Articular Disc

ItItItItItItItIt isisisisisisisis composedcomposedcomposedcomposedcomposedcomposedcomposedcomposed ofofofofofofofof:::::::: FibrousFibrous tissuetissue arrangedarranged inin 33 layerslayers

-- UpperUpper layerlayer

-- LowerLower layerlayer

-- MiddleMiddle layerlayer :: TheThe fibersfibers areare interlacinginterlacing

FewFew elasticelastic fibersfibers FibroblastsFibroblasts

ChondroidChondroid cellscells

the fibers run parallelthe fibers run parallelto the surfaceto the surface


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ARTICULAR DISCARTICULAR DISCCentral thin portion of the disc is avascularCentral thin portion of the disc is avascular

whereas the peripheral disc is highly vascularwhereas the peripheral disc is highly vascular

CentralCentralPortionPortion

PosteriorPosteriorBoundariesBoundaries

TMJ CapsuleTMJ Capsule


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11. LAYERS. LAYERS

a) Cellular intimaa) Cellular intima

b) Vascular subintimab) Vascular subintima

22. INTIMA. INTIMA -- CELL TYPESCELL TYPES

a) type Aa) type A -- macrophage like light cellsmacrophage like light cells

b) Type Bb) Type B -- fibroblast like dark cellsfibroblast like dark cells

Function of Synovial FluidFunction of Synovial Fluid

ProvidesProvides liquid environmentliquid environmentfor the joint surfacesfor the joint surfaces

ProvidesProvides lubricationlubrication toto

increase efficiency and reduceincrease efficiency and reduceerosionerosion

ProvidesProvides nutritionnutrition forfor TMJTMJ debatabledebatable


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Movement at the JointMovement at the Joint

Translatory Movement (Gliding )Translatory Movement (Gliding )

In the superior portion of the jointIn the superior portion of the joint

The disk and the condyle traverseThe disk and the condyle traverse anteriolyanteriolyalong the inclines of the articular tubercle toalong the inclines of the articular tubercle toprovide an anterior and inferior movement ofprovide an anterior and inferior movement ofthe mandibular headthe mandibular head

Hinge Movement (rotational movement)Hinge Movement (rotational movement)

In the inferior portion of the jointIn the inferior portion of the joint

Permits opening of the jawsPermits opening of the jaws

During Rest and Slight Jaw OpeningDuring Rest and Slight Jaw Opening(Hinge action)(Hinge action)


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Closed Jaw and Wide Jaw openingClosed Jaw and Wide Jaw opening

(Hinge and Glide action)(Hinge and Glide action)

TMJ ANATOMYTMJ ANATOMYduring Opening and Closureduring Opening and Closure


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Muscles of MasticationMuscles of Mastication

Muscles Moving The JointMuscles Moving The Joint

DepressionDepression-- lateral pterygoidlateral pterygoid

ElevationElevation-- temporalistemporalis,, massetermasseter,,

and medial pterygoidand medial pterygoid

ProtrusionProtrusion-- lateral and medial pterygoidlateral and medial pterygoid

Lateral motionLateral motion-- medial and lateralmedial and lateral

pterygoid, acting alternativelypterygoid, acting alternatively


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Ligaments Associated with Joint SupportLigaments Associated with Joint Support

LigamentsLigaments alongalong withwith thethe musclesmusclesprovideprovide stabilitystability forfor synovialsynovial jointjoint

33 ligamentsligaments areare associatedassociated withwith TMJTMJ::

TemporomandibularTemporomandibular ligamentligament:: laterallylaterally

SphenomandibularSphenomandibular ligamentligament:: mediallymedially

StylomandibularStylomandibular ligamentligament:: posteriorlyposteriorly

OnlyOnly TemporomandibularTemporomandibular ligamentligament hashas onlyonly

functionalfunctional significancesignificance,, thethe otherother twotwo havehave

onlyonly aa causalcausal relationshiprelationship toto thethe jointjoint

LateralLateral pterygoidpterygoid musclemuscle:: anteriorlyanteriorly

SPHENOMANDIBULARSPHENOMANDIBULAR

STYLOMANDIBULARSTYLOMANDIBULAR

TEMPOROMANDIBULARTEMPOROMANDIBULAR


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TheThe sensationssensations ofof painpain andand pressurepressure areare foundfound totobebe importantimportant symptomssymptoms inin TMJTMJ disordersdisorders::

ChangesChanges inin occlusionocclusion displacementdisplacement ofofcondylecondyle -- discdisc toto discdisc--fossafossa relationshiprelationshipirritateirritate nervenerve receptorsreceptors

InflammationInflammation inin synovialsynovial fluidfluid

producesproduces pressurepressure irritateirritate nervenerveendingending inin thethe synovialsynovial foldsfolds

MuscleMuscle tensiontension

Dislocation (Dislocation (luxationluxation & subluxation)& subluxation)

It occurs when the head of the condyle is displaced anteriorlyIt occurs when the head of the condyle is displaced anteriorly

over the articular eminence and cannot be returned voluntarily toover the articular eminence and cannot be returned voluntarily toits normal positionits normal position

ItIt isis characterizedcharacterized byby suddensudden lockinglocking andand immobilizationimmobilization ofofthethe jawsjaws whenwhen thethe mouthmouth isis open,open, accompaniedaccompanied byby prolongedprolonged

spasmodicspasmodic contractioncontraction ofof thethe temporalistemporalis,, medialmedial pterygoidpterygoid andandmassetermasseter musclesmuscles withwith protrusionprotrusion ofof thethe jawjaw

ItIt maymay occuroccur followingfollowing condylarcondylar fracture,fracture, oror inin

overstretching,overstretching, usuallyusually atat thethe attachmentattachment pointpoint ofof thethe laterallateralpterygoidpterygoid intointo thethe capsulecapsule


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TRAUMA AND DISLOCATIONTRAUMA AND DISLOCATION

OF THE TMJOF THE TMJ

May take place without the impact of an external forceMay take place without the impact of an external force

The dislocation is usually bilateral with an anteriorThe dislocation is usually bilateral with an anteriordisplacementdisplacement

E.gE.g.:.:Mouth opened unusually wide during yawning and theMouth opened unusually wide during yawning and thehead of the mandible may slip forward into thehead of the mandible may slip forward into theinfratemporal fossa causing articular dislocation of theinfratemporal fossa causing articular dislocation of the

jointjoint

Ankylosis of TMJAnkylosis of TMJ Debilitating condition involvingDebilitating condition involving immobility of jawimmobility of jaw

TraumaTrauma andand infectioninfection areare thethe mostmost commoncommon causescauses MayMay bebe ofof 22 typestypes::

11.. InIn intraintra--articulararticular ankylosisankylosis progressiveprogressive

destructiondestruction ofof meniscus,meniscus, flatteningflattening ofof

fossa,fossa, thickeningthickening ofof condyle,condyle, andand shrinkageshrinkage ofof

capsulecapsule partialpartial oror completecomplete abolitionabolition ofof thethe

jointjoint

22.. AfterAfter infection,infection, extraextra--articulararticular AnkylosisAnkylosis leadsleads totosplintingsplinting ofof thethe jointjoint byby aa fibrousfibrous oror aa bonybony

massmass externalexternal toto thethe jointjoint properproper


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Trauma to the TMJTrauma to the TMJ

Injury to the Articular DiscInjury to the Articular Disc

MayMay resultresult fromfrom inflammationinflammation andand moremore

commonly,commonly, malocclusionmalocclusion

MalocclusionMalocclusion usuallyusually resultsresults fromfrom abnormalabnormal

patternspatterns ofof mandibularmandibular excursionexcursion duringduring masticationmastication excessiveexcessive movementsmovements capsulecapsule isis overstretchedoverstretched preventsprevents tootoo greatgreat anan anterioranterior condylecondyle movementmovement

lossloss ofof adaptationadaptation ofof thethe discdisc toto thethe condylecondyle degenerationdegeneration ofof thethe discdisc


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CondyleCondyle appearsappears flattenedflattened inin outlineoutline RemnantRemnant ofof condylarcondylar cartilagecartilage sometimessometimes isispresentpresent inin agedaged jointsjoints

FibrousFibrous coveringcovering ofof thethe condylecondyle isis thickerthicker andandmaymay showshow chondroidchondroid changeschanges

OsteoporosisOsteoporosis ofof underlyingunderlying bonebone ofof thethe condylecondyle ArticularArticular discdisc becomesbecomes thinnerthinner andand exhibitsexhibits

hyalinizationhyalinization andand chondroidchondroid changeschanges andand teartearappearsappears inin smallsmall areasareas.. SimilarSimilar changeschanges arearefoundfound inin CTCT capsulecapsule

SynovialSynovial foldsfolds appearappear fibroticfibrotic wallwall ofof bloodbloodvesselsvessels areare thickenedthickened

NervesNerves appearappear decreaseddecreased inin numbernumber inin thethecapsulecapsule andand peripheralperipheral portionportion ofof thethe discdisc

Aging of the TMJAging of the TMJAging of the TMJAging of the TMJAging of the TMJAging of the TMJAging of the TMJAging of the TMJ

TMJTMJ -- INNERVATIONINNERVATION

Four types of nerve endings:Four types of nerve endings:

Have a variety of functionsHave a variety of functions

ProprioceptionProprioception

nociceptionnociception (pain)(pain)

mechanoreception.mechanoreception.

TYPESTYPES::

11.. FreeFree nervenerve endingsendings -- PainPain (peripheral(peripheral regionregion ofof disc)disc)..22.. RuffiniRuffini corpusclescorpuscles -- PosturePosture (dynamic/static)(dynamic/static) (Capsule)(Capsule)..

33.. MeissnersMeissners corpusclescorpuscles -- StaticStatic mechanoreceptionmechanoreception (Ligaments)(Ligaments)

44.. PacinianPacinian corpusclescorpuscles -- DynamicDynamic mechanoreceptionmechanoreception (Capsule)(Capsule)

sbard notes - 6

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