PAGE1PAGE6UnitFifteenNORMALANATOMYANDHISTOLOGYOFTHEORALMUCOSAANATOMYTheoralmucosamaybedividedintoareascorrespondingtotheanatomicconfigurationofthejawsandassociatedmusculature.Theseareasarethegingiva,buccalmucosa,labialmucosa,tongue,hardpalate,andsoftpalate.GingivaThegingivaor"gums"referstothetissuesurroundingtheteethandcoveringthealveolarbone.Thegingivaltissueistightlymattedtotheperiosteumofthealveolarbone,anditcoversthatportionoftherootsoftheteeththatextendsbeyondthecrestofalveolartoothsocket.Thegingivaltissuefillstheinterproximalspacesbetweentheteethsothatusuallyspacesarenotseenbetweenteeththatarenormallyalignedinthedentalarch.Theportionofthegingivathatextendsbeyondthealveolarboneandattachestotheteethisreferredtoasthemarginalgingivaorfreegingivalmargin,becauseitisrelativelyunsupportedbyhardtissueandformsacontinuousbandalongtheroot-crownjunctionoftheteeth.Thegingivaltissueattachestothetoothsurfacejustbelowthegingivalmargin,sothatasulcusorgingivalcreviceaboutlto2mmindepthisnormallyfoundbeneaththegingivalmargin.Theexactnatureofthegingivalattachmenttotoothhasnotbeenestablished,buttheattachmentisfirm,sothatgingivacannotbedetachedfromatoothunlessconsiderableforceisusedtotearthetissueorasurgicalknifeisusedtoseverthetissue.Thesurfaceofthemarginalgingivaissmooth;thatoftheattachedgingivaisstippled.Thegingivaltissueappearsalightpinkcolornormally.Beyondthegingivaandseparatedfromitbyacleardemarcationisthealveolarmucosa.Thelineofdemarcationofreferredtoasthemucogingivaljunction,andthealveolarmucosabeyondthisjunctionisloose,delicatetissuenotmatteddowntounderlyingbone.Numeroussmallbloodvesselscanbeseenthroughthisdelicatemucosa.Thealveolarmucosaontheouterorbuccalaspectiscontinuouswiththemucousmembraneofthelipandcheek,andavestibuleortroughisformedwheretheyblendintooneanother.Thistroughisreferredtoasthemucobuccalfoldorvestibuleofthemouth.BuccalandLabialMucosaThebuccalmucosaistheoralmucosaofthecheek;itcoversthebuccinatormuscle.Thebuccalmucousmembraneisfreelymovableandoverlieslooseconnectivetissueandadiposetissueasthemusculature.Thebuccalmucosaislightpinkincolorandsmoothintexture.Usually,aridgeorfoldoftissueappearsalongtheocclusallineoftheteeth;thisrepresentsatissueresponsetoconstantstimulationbytheteethduringmastication.Thisfoldmaybewhite-grayincolorandoccasionallymaybeconfusedwithwhitelesionsofthebuccalmucousmembrane.Abovetheocclusallineandintheposteriorpartofthebuccalmucosaoppositethemaxillarymolarteethisthepapillaoftheparotid(Stensen's)duct.Thisbilateralstructuremaynormallyappearquitelarge,andifinflameditmaysimulateatumor.Anteriorly,thebuccalmucosablendsintothelabialmucosa,whichcoversthemasculatureofthelip.Thelipisamucocutaneousjunction,andthemucosalandskinsurfacesareseparatedatthevermilionborderofthelip.Withthelipsclosed,thevisibleareaisskin.Posteriorly,thebuccalmucosablendsintothetonsillararea.TongueThetongueisahighlyspecializedorganwithnumerousfunctions:taste,speech,mastication,andsensation,tolistthemoreimportantones.Thelingualmucousmembranecoversahighlycomplexmuscularsystemandmustbeadaptedtocontinuousirritationalstimuliofvaryingnature.Themucosacoveringthedorsalsurfaceofthetongueisroughintextureandiscomposedoflargenumbersofminutepapillae.Themajorgroupoflingualpapillaeisthefiliformpapillae,whicharesmallandpunctateinappearance,givingthetongueafileliketexture.Scatteredamongthesearethelargefungiform,whichappearsomewhatredderincolor.AttheposteriorborderthelingualdorsumisthelargecircumvallatepapillaearrangedinaV-shapedconfiguration,withthepointfacingtheorophargnx.Thereareapproximately8to10circumvallatepapillaearrangedintwodiagonalrows.Intheposteriorportionofthelateralborderofthetonguearethefoliatepapillaered,irregularlyshapedsoftmassesoflymphoidtissue.Themucosaoftheventralsurfaceofthetongueissmoothanddelicate,withnopapillarystructures.Themucosaoftheventralsurfaceofthetongueblendsintothemucosaofthefloorofthemouth;alingualfrenumrunsfromtheventralsurfaceofthetonguetothefloorofthemouth.FloorofMouthThemucosaherecoversthesublingualglandsandthemylohyoidandgeniohyoidmuscles.Thefloorofthemouthistherelativelysmallareaanteriortothelingualattachment.Itextendsposteriorlyoneithersideofthetonguetoformanarrowvestibulebetweenthetongueandmandibularteeth.Anteriorly,themucosaofthefloorofthemouthblendsintothelingualportionofthemandibulargingiva.AnteriortotheattachmentofthelingualfrenumaretwodiagonalridgesmeetinginthemidlinetoformaVconfigurationpointinganteriorly.Alongtheseridegesorsublingualcarunculaopenthenumerousductsofthesublingualglands.HardPalateThemucosaofthehardpalatecoversthepalatalosseousstructureandisfirmlyattachedtotheunderlyingconnectivetissue,althoughsomedisplacement,ofthismucosaltissueispossible.Numerousmucousglandsliebeneaththepalatalmucosa,andtheirductsappearonthepalatalsurfaceaslargenumbersofsmallpores.Anteriorly,thehardpalatepresentsnumerousfoldsoffirmtissue.SoftPalateThesoftpalateisthatpalatalmucosaposteriortotheosseousstructureofthepalate.Thesoftpalateismorefreelymovablethanthehardpa1ate,andthedemarcationbetweenhardandhavingapersonopen.hismouthwideandexposehisthroateasilyseessoftpalate.Inthisactionthesoftpalatefoldsupward.Thesoftpalateblendsintotheuvulaposteriorlyinthemidline.TonsillarArea(Fauces)Thebilateralpalatinetonsilslieinspacesinferiortoandcontinueouswiththesoftpalate.Thepharyngopalatinearchboundthesespacesanteriorlybytheglossopalatinearchandposteriorly.Thetonsillarspacesandtheareabetweenthemarealsoreferredtoasthefauces.Theglossopalatineandpharyngopalatinearchesareusuallyreferredtoastheanteriorandposteriorpillarsofthefauces.Thefloorofthefaucesisrepresentedbythedorsumoftheposteriorportionofthetongue.Thetonsilsarecomposedoflymphoidtissue;theyaresoftandhavearedordeeppinkpapillarysurface.OropharynxBeyondtheposteriorpillarsofthefaucesistheoropharynx,thatpartofthepharynxlyingbetweenthenasopharynxandlaryngealpharynx.Itextendsfromthesoftpalatetothelevelofthehyoidbone.Theoropharyngealmucosacoversthemusclesofthepharynxandoftencontainsaccumulationsoflymphoidtissuesothatthecolorofthepharyngealmucosaispink.withoccasionalraisedreddishareas.HISTOLOGYOFOBALMUCOSAOralmucousmembraneisessentiallysimilartoskinbutlacksthesecondarystructuresorskinappendages.Theoralmucosaiscomposedofasurfacestratifiedsquamousepitheliumandanunderlyingconnectivetissuecoriumorlaminapropria.Thereissomevariationinthestructureoforalmucosaindifferentareasofthemouth,dependinguponenvironmentandphysiologicprocesses,butabasicstructureofmucosacanbeoutlinedandthevariationmentioned.Theepitheliumoforalmucosaisusuallythickerthanthatofskinandhasdeeperextensionsofretepegsintotheunderlyingconnectivetissue.Thestratifiedsquamousepitheliumhasthreelayers.Thestratumgerminativumorbasallayerisimmediatelyadjacenttotheconnectivetissueandrepresentsthegerminallayeroftheepithelium.Thebasalcellsarecuboidalorcolumnarwithlargedeeplystainingnuclei;theyarearrangedinauniformrow,oneortwocellsthick.Theyareseparatedfromunderlyingconnectivetissuebyaso-calledbasementmembrane.Abovethebasallayeristhestratumspinosumorprickle-celllayer.Thisisarelativelywidezoneofpolyhedralcellswithlargenuclei.Thenucleistainlessintenselythanthoseofthebasallayer,andforthisreasonthebasallayerisusuallywelldemarcatedfromtheoverlyingprickle-celllayer.Theindividualcellsofthestratumspinosumareclearlyoutlinedbycellwalls,andthecellsareslightlyseparatedandappeartobejoinedbyfineprotoplasmicprocesses,referredtoasintercellularbridges.Theseprocessesorintercellularfibrilsareresponsiblefortheprickle-cellconnotation.Thecellsofthestratumspinosumtendtoflattenastheyapproachthesurfacelayers.Thestratumgranulosumorgranularlayerliesabovethestratumspinosumandiscomposedofseverallayersofflattenedcellsthatcontainlargenumbersofdeeplystaininggranulesinthecytoplasm.Thesehavebeenreferredtoaskeratohyalingranules.Inskin,astratumlucidumorthinclearzoneoftenoccursabovethestratumgranulosum.Howevethiszoneisnormallyabsentinoralmucosa.Thesurfacezoneisthekeratinizedorcornifiedlayerreferredtoasthestratumcorneum.Thestratumcorneumiscomposedofvaryingamountsofkeratin,usuallystructurelessfinelayersofeosinophilicmaterialwithoccasionalcellnucleipresentorclearspacesrepresentingdegeneratednuclei.Thedepthofthestratumcorneumvariesconsiderablyinoralmucosa,dependinguponthenatureofthetissue.Areasofthemouth.thatreceivelittlestimulationortraumaticinfluenceseitherarenonkeratinizedorhaveaverythinstratumcorneum.Thefloorofthemouth,ventralsurfaceofthetongue,andsoftpalatefallintothiscategory.Generally,however,theoralmucosahasadefinitestratumcorneum,althoughthedepthisconsiderablylessthanthatofskin.Ithasbeenshownthatstimulationoforalmucosaresultsinincreasedkeratinization.Wherethestratumcorneumisthin,thestratumgranulosumisindistinctandmayappeartobeabsent.Asthedepthofstratumcorneumincreases,thestratumgranulosumbecomeslargerandmoreobvious.Theretepegsoffingerlikeprocessesthatextendintoconnectivetissuearemoreobviousanddeeperthaninskin.Betweentheepithelialretepegsareconnectivetissueextensionsordermalpapillae.Theepitheliumandconnectivetissueareseparatedbyaso-calledbasementmembrane,whichisreallypartoftheconnectivetissuegroundsubstanceandstainsdeeplyforacidmucopolysaccharides.Thismaymerelyrepresentazoneofcondensedgroundsubstancebeneaththeepithelium.Atruebasementmembrane-likestructurehasbeendescribedinelectronmicroscopestudiesoforalmucosa,butitswidthis600Angstromunitsandwouldbeinvisiblewithlightmicroscopy.Theconnectivetissueiscomposedofdensebundlesofcollagenfibersandnumeroussmallbloodvesselsandnerves.Thecharacteristiccellofconnectivetissueisthefibroblast,alargespindleshapedcell.Normally,thesecellsarescatteredsparselythroughouttheconnectivetissue.Thedeeperlayersoftheconnectivetissueareoftenreferredtoassubmucosa,andtheirfunctionistobindmucosatounderlyingmuscleorbone.Largerbloodvesselsandnumerousmucousglandsappearinthedeeperlayersoftheconnectivetissue.Mucousglandsareanintegralpartofthenormalmucousmembranestructure;theysecretemucus,whichiscarriedtothesurfacebyfineducts.Themucousglandsarenormallyfewinnumber,butlargenumbersmayoccurincertainareasoftheoralmucosa,suchasthehardpalateandoccasionallythelowerlip.Sebaceousglandsnormallyarenotpresentintheconnectivetissueoforalmucosa,buttheymayappearasadevelopmentalanomaly.Ingeneralterms,theoralmucosaiscomposedofthreemaintypes.Afunctioningmucosasuchasthatofthegingivaandhardpalateiswellkeratinizedandhasadenseconnectivetissue.Thistypeofmucosaisfirmlyattachedtounderlyingbone,andthemarginalgingivaisattachedtothetoothsurfacebyaspecializedformofadaptationororganicunionwithenamelorcementumclosetotheenamel-cementalborder.Iftheteetharelost,thegingivabecomesedentulousalveolarmucosa,andthisagainisafirm,functioningmucosa.Anonfunctioningormereliningmucosaisthetypethatoccursonthelip,floorofthemouth,ventralsurfaceofthetongue,andbuccalregion.Themucousmembraneofthisareaisfreelymovableandnotattachedtoafirmosseousstructure.Theattachmentinvolvesmusculature,andthemucosaisnotgreatlyaffectedbymasticatorystimulationortraumaticinfluencesbecauseitiseasilypushedasidebypressure.Themucosaintheseareasisrelativelyslightlykeratinized,andtheconnectivetissueissomewhatlooserintexture.Thethirdtypeoforalmucosa,thedorsumofthetongue,ishighlyspecificandhasaspecializedfunction.Thesurfaceiscomposedofpapillarystructuresofthreemaintypes:filiformpapillaearesmall,cone-shaped,highlykerratinizedepithelialstructures.Fungiformpapillaearewide,mushroom-shapedpapillaryprojectionscomposedofconnectivetissuecoveredwithathinstratifiedsquamousepithelium.Circumvallatepapillaearelargerpapillarymassesseparatedfromadjoiningtissuebydeepgrooves.Thesearecomposedofconnectivetissuecoveredwithepithelium.Tastebudsarefoundonthelateralsurfacesofthecircumvallatepapillae.ThegroovesorfurrowsoverlieEbnet'sglands,whichsecreteanalbuminoussubstanceintothefurrows.Foliatepapillaearecomposedofmassesoflymphoidtissuewithacharacteristicfollicularstructure.VOCABULARYl.configuration輪廓，外貌2.jaw頜，顱骨3.musculature肌肉系統4.gingiva牙齦5.buccalmucosa頰粘膜6.labialmucosa唇粘膜7.tongue舌8.hardpalate硬腭9.softpalate軟腭10.gum齦，牙床11.alveolar牙槽的12.mat墊13.periosteum骨膜14.crest嵴頂15.socket槽16.interproximal鄰間的17.aligne聯合18.marginalgingiva邊緣齦19.sulcus槽，溝20.stipple點彩21.demarcation分界22.alveolarmucosa牙槽粘膜23.mucogingivaljunction膜齦聯合24.lip唇25.cheek頰26.mucobuccalfold頰粘膜皺襞27.vestibule前庭28.buccinatormuscle頰肌29.labialfrenum唇系帶30.parotidduct(stensen)腮腺導管31.palatinetonsil腭扁桃腺32.foliatepapillae葉狀乳頭33.lingualtonsil舌扁桃腺34.submaxillaryduct(warton)頜下腺導管35.uvula懸雍垂36.oropharynx口咽部37.circumvallatepapillae輪廓乳頭38.dorsumoftongue舌背39.ventrumoftongue舌腹40.lingualfrenum舌系帶41.sublingualridgeandduct舌下肉阜和導管42.gingivalpapillae齦乳頭43.attachedgingiva附著齦44.adipose脂肪；脂肪的45.texture