The Larynx · • The central cavity of the larynx is tubular in shape and is lined by mucosa • Support is provided by the fibro-elastic membrane of larynx and by the cartilages
Post on 28-Jul-2020
2 Views
Preview:
Transcript
TheLarynxProf. Dr.Mohammed Hisham Al-Muhtaseb
TheLarynx
• ExtendsfromthemiddleofC3vertebratillthelevelofthelowerborderofC6
• ContinueasTrachea
• Aboveitopensintothelaryngo-pharynx
• Suspendedfromthehyoidboneaboveandattachedtothetracheabelowbymembranesandligaments
Functions
• 1.actsasanopenvalveinrespiration
• 2.Actsasaclosedvalveindeglutition
• 3.Actsasapartiallyclosedvalveintheproductionofvoice
• 4.Duringcoughitisfirstclosedandthenopensuddenlytoreleasecompressedair
Parts
• 1.Cartilage
• 2.Mucosa
• 3.Ligaments
• 4.Muscles
Cartilage
• A.Single:EpiglottisCricoidThyroid
B.Pairs:ArytenoidCuneiformCorniculate
Cricoidcartilage
• Themostinferiorofthelaryngealcartilages
• Completelyencirclestheairway
• Shapedlikea'signetring'
• Broadlaminaofcricoidcartilageposterior
• Muchnarrowerarchofcricoidcartilage circlinganteriorly.
Cricoidcartilage• Posteriorsurfaceofthelaminahastwooval
depressionsseparatedbyaridge
• The esophagus isattachedtotheridge
• Depressionsareforattachmentoftheposteriorcrico-arytenoidmuscles.
• Hastwoarticularfacets oneachside
• Onefacetisontheslopingsuperolateralsurfaceandarticulateswiththebaseofanarytenoidcartilage;
• Theotherfacetisonthelateralsurfacenearitsbaseandisforarticulationwiththeinferiorhornofthethyroidcartilage
Thyroidcartilage• Thelargestofthelaryngealcartilages
• Itisformedbyarightandaleftlamina
• Widelyseparatedposteriorly,butconvergeandjoinanteriorly
• Posteriormarginofeachlaminaiselongatedtoformasuperiorhorn andaninferiorhorn
Thyroidcartilage• Mostsuperiorpointofthesiteoffusionbetweenthetwolaminaeisthelaryngealprominence ('Adam'sapple')
• Anglebetweenthetwolaminaeismoreacuteinmen(90°)thaninwomen(120°)
• Superiortothelaryngealprominence,thesuperiorthyroidnotch separatesthetwolaminae
• Superiorthyroidnotchandthelaryngealprominencearepalpable landmarksintheneck
• Lessdistinctinferiorthyroidnotch inthemidlinealongthebaseofthethyroidcartilage.
Thyroidcartilage
• Themedialsurfaceoftheinferiorhornhasafacetforarticulationwiththecricoidcartilage;
• Thesuperiorhornisconnectedbya ligamenttotheposteriorendofthegreaterhornofthehyoidbone.
• Lateralsurfaceoflaminaismarkedbyaridge(theobliqueline),whichcurvesanteriorlyfromthebaseofthesuperiorhorntotheinferiormarginofthelamina.
• Endsoftheobliquelineareexpandedtoformsuperior andinferiorthyroidtubercles
• Theobliquelineisasiteofattachmentfortheextrinsicmuscles ofthelarynx(sternothyroid,thyrohyoid,andinferiorconstrictor).
Epiglottis• Isa'leaf-shaped'cartilageattachedbyitsstemtotheangleofthethyroidcartilage
• Projectsposterosuperiorlyfromitsattachmenttothethyroidcartilage.
• Theattachmentisviathethyro-epiglotticligament inthemidlinebetweenthelaryngealprominenceandtheinferiorthyroidnotch
• Theuppermarginoftheepiglottisisbehindthepharyngealpartofthetongue.
• Theinferiorhalfoftheposteriorsurfaceoftheepiglottisisraisedslightlytoformanepiglottictubercle.
Arytenoidcartilages
• Twoarytenoidcartilagesarepyramid-shapedcartilageswiththreesurfaces
• Baseofarytenoidcartilage andanApexofarytenoidcartilage
• The base ofarytenoidcartilageisconcaveandarticulateswiththefacetonthesuperolateralsurfaceofthecricoidcartilage;
• Theapexofarytenoidcartilagearticulateswithacorniculatecartilage;
• Themedialsurface ofeachcartilagefacestheother;
Arytenoidcartilages
• Theanterolateralsurface hastwodepressions,separatedbyaridge,formuscle(vocalis) andligament(vestibularligament) attachment.
• Theanteriorangleofthebaseofarytenoidcartilageiselongatedintoavocalprocess towhichthevocalligament isattached
• Thelateralangleissimilarlyelongatedintoamuscularprocess forattachmentoftheposteriorandlateralcrico-arytenoidmuscles.
CorniculateandCuneiform• Thecorniculatecartilagesaretwosmallconicalcartilages
• Basesarticulatewiththeapicesofthearytenoidcartilages
• Theirapicesprojectposteromediallytowardseachother.
• TheCuneiform aretwosmallclub-shapedcartilages
• Lieanteriortothecorniculatecartilages
• Suspendedinthepartofthefibroelasticmembranethatattachesthearytenoidtheepiglottis.
Ligaments
Extrinsicligaments
• Thyrohyoidmembrane
• Hyo-epiglotticligament
• Cricotrachealligament
Thyrohyoidmembrane
• Toughfibroelasticligamentthatspansbetweenthesuperiormarginofthethyroidcartilagebelowandthehyoidbone
• Attachedtothethyroidlaminaeandadjacentanteriormarginsofthesuperiorhorns
• Ascendsmedialtothegreaterhornsandposteriortothebodyofthehyoidbonetoattachtothesuperiormarginsofthesestructures.
• Anaperture inthelateralpartofthethyrohyoidmembraneoneachsideisforthesuperiorlaryngealarteries,nerves,andlymphatics
Thyrohyoidmembrane
• Theposteriorbordersofthethyrohyoidmembranearethickenedtoformthelateralthyrohyoidligaments.
• Alsothickenedanteriorlyinthemidlinetoformthemedianthyrohyoidligament.
• Occasionally,thereisasmallcartilage(triticealcartilage)ineachlateralthyrohyoidligament.
Extrinsicligaments
• Cricotrachealligament runsfromthelowerborderofthecricoidcartilagetotheadjacentupperborderofthefirsttrachealcartilage.
• Thehyo-epiglotticligamentextendsfromthemidlineoftheepiglottis,anterosuperiorlytothebodyofthehyoidbone.
Intrinsicligaments
• Thefibro-elasticmembraneoflarynxlinkstogetherthecartilagesandcompletesthearchitecturalframeworkofthelaryngealcavity
• Itiscomposedoftwoparts-alowercricothyroidligament andanupperquadrangularmembrane.
Cricothyroidligament• Cricovocalmembraneorcricothyroidmembrane
• Attachedtothearchofcricoidcartilageandextendssuperiorly
• Endinafreeuppermargin withinthespaceenclosedbythethyroidcartilage
• Upperfreemarginattaches:
• Anteriorly tothethyroidcartilage;• Posteriorly tothevocalprocesses ofthearytenoid
cartilages.
• Thefreemarginisthickenedtoformthevocalligament,whichisunderthevocalfold (true 'vocalcord')ofthelarynx.
• Thecricothyroidligamentisalsothickenedanteriorlytoformamediancricothyroidligament
• Inemergencysituations,themediancricothyroidligamentcanbeperforatedtoestablishanairway
Quadrangularmembrane
• Runsbetweenthelateralmarginoftheepiglottisandtheanterolateralsurfaceofthearytenoidcartilage
• Attachedtothecorniculatecartilage
• Freeuppermarginandafreelowermargin
• Freelowermargin isthickenedtoformthevestibularligament underthevestibularfold (false 'vocalcord')
Quadrangularmembrane
• Vestibularligamentisseparatedfromthevocalligamentbelowbyagap
• Whenviewedfromabovethevestibularligamentislateraltothevocalligament
CartilageandLigaments
Laryngealjoints
Cricothyroidjoints• Betweentheinferiorhornsofthethyroidcartilageandthecricoidcartilage,aresynovial
• Surroundedbyacapsuleandisreinforcedbyassociatedligaments
• Enablethethyroidcartilagetomoveforwardandtiltdownwards onthecricoidcartilage
• Forwardmovementanddownwardrotationofthethyroidcartilageeffectivelylengthensandputstensiononthevocalligaments
Crico-arytenoidjoints• Betweenarticularfacetsonthesuperolateralsurfacesofthecricoidcartilageandthebasesofthearytenoidcartilages
• Enablethearytenoidcartilagestoslideawayortowardseachotherandtorotate
• Thevocalprocessespivoteithertowardsorawayfromthemidline.
• Thesemovementsabductandadductthevocalligaments
Cavityofthelarynx
Laryngealcavity• Thecentralcavityofthelarynxistubularinshapeandislinedbymucosa
• Supportisprovidedbythefibro-elasticmembraneoflarynxandbythecartilagestowhichitisattached.
• Thesuperiorapertureofthecavity(laryngealinlet) opensintotheanterioraspectofthepharynxjustbelowandposteriortothetongue
• laryngealinletisoblique andpointsposterosuperiorly
laryngealinlet
• Anteriorborderisformedbymucosacoveringthesuperiormarginoftheepiglottis
• Lateralbordersareformedbymucosalfolds(aryepiglotticfolds),
• Posteriorborderinthemidlineisformedbyamucosalfoldthatformsadepression(interarytenoidnotch)betweenthetwocorniculatetubercles
• Aryepiglotticfolds
• Enclosethesuperiormarginsofthequadrangularmembranesandadjacentsofttissues
• Twotuberclesonthemoreposterolateralmarginsidemarkthepositionsoftheunderlyingcuneiformandcorniculate cartilages;
Inferioropening• Inferioropeningofthelaryngealcavityiscontinuouswiththelumenofthetrachea
• Completelyencircledbythecricoidcartilage
• Horizontalinpositionunlikethelaryngealinlet
• Theinferioropeningiscontinuouslyopenwhereasthelaryngealinletcanbeclosedbydownwardmovementoftheepiglottis
Divisionintothreemajorregions
• Thevestibularandvocalfolds,divideitintothreemajorregions-thevestibule,amiddlechamber,andthe infraglotticcavity
• Thevestibule istheupperchamberofthelaryngealcavitybetweenthelaryngealinletandthevestibularfolds
• Vestibularfoldsenclosethevestibularligamentsandassociatedsofttissues;
Divisionintothreemajorregions
• Themiddlepart ofthelaryngealcavityisverythinandisbetweenthevestibularfoldsaboveandthevocalfoldsbelow
• Vocalfoldsenclosethevocalligamentsandrelatedsofttissuesbelow.
• Theinfraglotticspace isthemostinferiorchamberandisbetweenthevocalfoldsandtheinferioropeningofthelarynx;
VocalFolds• Consistof:• Vocalligament
• Mucousmembrane(stratifiedsquamous)
• Vocalismuscle
• Nosubmucosa
• Nobloodvessels(whiteincolor)
• Oneachsideextendbetweenthevocalprocessofthearytenoidandthebackoftheanteriorlaminaofthyroid.
• Longerinmalewhichcausethedifferenceofthepitchofthevoicebetweengenders
Vestibularfolds• Falsevocalcords
• Vestibularfoldsenclosethevestibularligamentsandassociatedsofttissues
• Vascularised(redincolor)
• Fixedandnotmovableunlikethevocalcord
• Superiortothevocalcord
Laryngealventriclesandsaccules• Oneachside,themucosaofthemiddlecavitybulgeslaterallythroughthegapbetweenthevestibularandvocalligamentstoproducealaryngealventricle
• Tubularextensionofeachventricle(laryngealsaccule)projectsanterosuperiorlybetweenthevestibularfoldandthyroidcartilage
• Withinthewallsoftheselaryngealsacculesarenumerousmucousglands.
• Mucus secretedintothesacculeslubricatesthevocalfolds.
Rimavestibuliandrimaglottidis
• Rimavestibuli isatriangular-shapedopeningbetweenthetwoadjacentvestibularfolds attheentrancetothemiddlechamber
• Apexoftheopeningisanterioranditsbaseisposterior
• TheRimaglottidisisformedbythevocalfolds(truevocalcords) andadjacentmucosa-coveredpartsofthearytenoidcartilages
Rimavestibuliandrimaglottidis• Rimaglottidisopeningseparatesthemiddlechamberabovefromtheinfraglotticcavity
• Thebaseofitisformedbythefoldofmucosa(interarytenoidfold)atthebottomoftheinterarytenoidnotch
• Rimaglottisisthenarrowestpartofthelaryngealcavity
• Boththerimaglottidisandtherimavestibulicanbeopenedandclosedbymovementofthearytenoidcartilagesandassociatedmembranes.
Muscles
Intrinsicmuscles
• Adjusttensioninthevocalligaments,
• Openandclosetherimaglottidis,
• Controltheinnerdimensionsofthevestibule,
• Closetherimavestibuli
Cricothyroidmuscles• Fan-shapedmuscles
• Attachedtotheanterolateralsurfacesofthecricoidcartilageandexpandsuperiorlyandposteriorlytoattachtothethyroidcartilage
• Eachmusclehasanobliquepartandastraightpart:
• Theobliquepart runsinaposteriordirectionfromthearchofthecricoidtotheinferiorhornofthethyroidcartilage
• Thestraightpart runsmoreverticallyfromthearchofthecricoidtotheposteroinferiormarginofthethyroidlamina
Cricothyroidmuscles• Pullthethyroidcartilageforwardandrotate itdownrelativetothecricoidcartilage
• TheseactionsTensesvocalcords
• Aretheonlyintrinsicmusclesinnervatedbythesuperiorlaryngealbranches ofthevagusnerves
• Allotherintrinsicmusclesareinnervatedbytherecurrentlaryngealbranches ofthevagusnerves
Posteriorcrico-arytenoidmuscles• Thereisarightandaleftposteriorcrico-arytenoid
• ThefibersofeachmuscleoriginatefromtheBackofcricoidcartilage,andrunsuperiorlyandlaterallytothemuscularprocessesofthearytenoidcartilage
• Abductsthevocalcords byrotatingarytenoidcartilage
• Innervatedbytherecurrentlaryngealbranchesofthevagusnerves
Lateralcrico-arytenoidmuscles
• MuscleoneachsideoriginatesfromtheUpperborderofcricoidcartilage,andrunsposteriorlyandsuperiorlytoinsertonthemuscularprocessofthearytenoid
• Adductsthevocalcords byinternallyrotatingarytenoidcartilage
• Innervatedbytherecurrentlaryngeal
Transversearytenoid
• OriginatesfromBackandmedialsurfaceofarytenoidcartilageandinsertintheBackandmedialsurfaceofoppositearytenoidcartilage
• Closesposteriorpartofrimaglottidis byapproximatingarytenoidcartilages
• Recurrentlaryngealnerve
Thyroarytenoid(vocalis)
• FromtheInnersurfaceofthyroidcartilagetotheArytenoidcartilage
• Relaxesvocalcords
• Recurrentlaryngealnerve
Obliquearytenoid
• FromtheMuscularprocessofarytenoidcartilagetotheApexofoppositearytenoidcartilage
• Narrowstheinlet bybringingthearyepiglotticfoldstogether
• Recurrentlaryngealnerve
Thyroepiglottic(aryepiglotticmuscles)
• FromtheMedialsurfaceofthyroidcartilagetotheLateralmarginofepiglottisandaryepiglotticfold
• Widenstheinlet bypullingthearyepiglotticfoldsapart
• Recurrentlaryngealnerve
Extrinsicmuscles• Elevatorsofthelarynx:• 1.Digastricmuscle• 2.Stylohyoid• 3.Myelohyoid• 4.Geniohyoid
• Thelarynxmovesupinswallowingbythesemusclesassistedby:• Stylopharngeus,Salpingo-pharngeus,AndPalatopharngeus.
• Depressorsofthelarynx:• 1.Sternothyroid• 2.Sternohyoid• 3.Omohyoid
MusclesandCavity
Functionofthelarynx
Respiration• Duringquietrespiration,thelaryngealinlet,vestibule,rimavestibuli,andrimaglottidisareopen
• Duringforcedinspirationthearytenoidcartilagesarerotatedlaterally,mainlybytheactionoftheposteriorcrico-arytenoidmuscles.
• Asaresult,thevocalfoldsareabducted,andtherimaglottidiswidens intoarhomboidshape,effectivelyincreasesthediameterofthelaryngealairway.
Phonation
• Whenphonating,thearytenoidcartilagesandvocalfoldsareadducted andairisforcedthroughtheclosedrimaglottidis
• Thisactioncausesthevocalfoldstovibrate againsteachotherandproducesounds
• Canthenbemodifiedbytheupperpartsoftheairwayandoralcavity
• Tension inthevocalfoldscanbeadjustedbythevocalisandcricothyroidmuscles.
Effortclosure
• Effortclosureofthelarynxoccurswhenairisretainedinthethoraciccavitytostabilizethetrunk
• Forexampleduringheavylifting,oraspartofthemechanismforincreasingintra-abdominalpressure
• Therimaglottidisiscompletelyclosed,asistherimavestibuliandlowerpartsofthevestibule
• Theresultistocompletelyandforcefullyshuttheairway.
Swallowing• Duringswallowing,therimaglottidis,therimavestibuli,andvestibuleareclosed andthelaryngealinletisnarrowed
• Thelarynxmovesupandforward
• Thisactioncausestheepiglottis toswingdownward toeffectivelynarroworclosethelaryngealinlet
• Theupandforwardmovementofthelarynxalsoopenstheesophagus
• Alltheseactionstogetherpreventsolidsandliquidsfromentryintotheairway
BloodSupply
Arteries
• Themajorbloodsupplytothelarynxisbythesuperiorandinferiorlaryngealarteries
• Thesuperiorlaryngealarteryoriginatesfromthesuperiorthyroidbranchoftheexternalcarotidartery,
• Accompaniestheinternalbranchofthesuperiorlaryngealnervethroughthethyrohyoidmembranetoreachthelarynx.
Arteries
• Theinferiorlaryngealarteryoriginatesfromtheinferiorthyroidbranchofthethyrocervicaltrunkofthesubclavianartery
• Togetherwiththerecurrentlaryngealnerve,ascendsinthegroovebetweentheesophagusandtrachea
• Itentersthelarynxbypassingdeeptothemarginoftheinferiorconstrictormuscleofthepharynx;
Veins
• Veinsdrainingthelarynxaccompanythearteries:
• Superiorlaryngealveinsdrainintosuperiorthyroidveins,whichinturndrainintotheinternaljugularveins
• Inferiorlaryngealveins drainintoinferiorthyroidveins,whichdrainintotheleftbrachiocephalicveins.
Lymphatics
• Lymphaticsdrainregionsaboveandbelowthevocalfolds:
• Thoseabovethevocalfoldsfollowthesuperiorlaryngealarteryandterminateindeepcervicalnodes
• Thosebelowthevocalfoldsdrainintodeepnodesassociatedwiththeinferiorthyroidartery
• Orwithnodesassociatedwiththefrontofthecricothyroidligamentoruppertrachea.
Innervations
Superiorlaryngealnerves
• Thesuperiorlaryngealnervesoriginatefromtheinferiorvagalgangliahighintheneck
• Theydescendmedialtotheinternalcarotidarteryanddivideintointernalandexternalbranches abovethehyoidbone
• Theexternalbranch(externallaryngealnerve)descendsalongthelateralwallofthepharynxtosupplytheinferiorconstrictorofthepharynxandendsbysupplyingthecricothyroidmuscle;
Superiorlaryngealnerves
• Theinternallaryngealnervepassesanteroinferiorlytopenetratethethyrohyoidmembrane
• Internalnerveismainlysensory andsuppliesthelaryngealcavitydowntothelevelofthevocalfolds.
Recurrentlaryngealnerves
• Therecurrentlaryngealnervesare:
• Sensorytothelaryngealcavitybelowthelevelofthevocalfolds;
• Motortoallintrinsicmusclesofthelarynxexceptforthecricothyroid.
Recurrentlaryngealnerves
• Theleft recurrentlaryngealnerveoriginatesinthe thoraxwhereastheright recurrentlaryngealnerveoriginatesintherootoftheneck
• Bothnervesgenerallyascendintheneckinthegroovebetweentheesophagusandtrachea
• Enterthelarynxdeeptothemarginoftheinferiorconstrictor
Relationsofthelarynx
• Oneachside:
• Carotidsheath(contents),andlaterallobeofthethyroidgland
• Posterior:• Pharynxandtherightrecurrentlaryngealnerve
• Anterior:
• Skin,fasciaanditscontents,4infra-hyoidmuscles
Clinicalnotes
Thyroidoctomy
• Sectioningoftheexternallaryngeal nervemighthappeninthyroidoctomy
• Duetothecloserelationshipbetweentheexternallaryngealnerveandthesuperiorthyroidartery.
• Producesweaknessinvoice sincethevocalcordscannotbetensed(criciothyroidM.).
SectionoftheRecurrentlaryngealnerve
• 1.Unilateralcompletesection:
• Onevocalfold(ontheaffectedside)inthepositionmidwaybetweenabductedandadducted
• Speechnotgreatlyaffectedastheothervocalcordcompensatefortheaction.
SectionoftheRecurrentlaryngealnerve
• 2.Bilateralcompletesection:
• Bothvocalfoldsinpositionmidwaybetweenabductedandadducted
• Breathingisimpairedsincetherimaglottisispartiallycloseandspeechislost
SectionoftheRecurrentlaryngealnerve
• 3.Unilateralpartialsection:
• Thisresultsinagreaterdegreeofparalysisoftheabductormusclesthanoftheadductor.
• Thereforetheaffectedcordisintheadductedmidlineposition
• Hoarsenessofthevoice(theothervocalfoldcompensatestheaction)
SectionoftheRecurrentlaryngealnerve
• 4.Bilateralpartialsection:
• Thisresultsinbilateralparalysisoftheabductormuscles
• Thereforethevocalfoldsareadductedtogetherinthemidline
• Acutebreathlessness(Dyspnea)andstridorfollow
• Leadtosuffocationsotracheostmyisnecessary
Thankyou
top related