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

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