甲状腺解剖.ppt

1、ThyroidAnatomy,13#,ThyroidAnatomy13/13,ThyroidAnatomy12/13,Mostoftheanterolateralsurfaceoftheneckiscoveredbythethinplatysmamuscles,remnantsofthepanniculuscarnosusofmammals(watchadogshakeitscoat).Thismuscleisatthelevelofthesuperficialfasciaanditsundersideprovidesanexcellentplaneofdissectionexposingth

2、edeepfasciaoftheneck.BecauseoftheinvertedV-shapedgapinthislayeranteriorly,dissectionofflapsinacollarincisionshouldbeginlaterally.,ThyroidAnatomy11/13,Thesternocleidomastoidmusclesflankthestrapsandcovertheinternaljugularsandcarotidsheaths.Theyareenclosedinanencirclinggirdleofdeepcervicalfasciacalledt

3、heinvestinglayer.Thislayercontinuesposteriorlytoenclosethetrapeziusmuscles(seeneckclinicalfolio).Theexternaljugularveinsdescendacrosstheposteriorportionsofthesternocleidomastoidsandanteriorjugularveinsdescendalongthestrapsanteriorly.,ThyroidAnatomy10/13,Thethyroidiscoveredbythesternohyoidandsternoth

4、yroid(strap)muscles.Theseareenclosedinanintermediatelayerofdeepcervicalfascia(seeThryoidAnatomy:1)withthesternohyoidsbeingapposedinthemidlineandtheunderlyingsternothyroidsbeingslightlymorelateral.Whenmobilizingthestrapsitisimportanttostayintheplanedeeptobothmuscles.Theomohyoidmusclesascenddiagonally

5、acrosstheupperpartofthestrapsandareautomaticallymobilizedwiththosemuscles.,ThyroidAnatomy9/13,Venousdrainageofthethyroidrunswiththesuperiorlaryngealarteriesabove,passeslaterally(middlethyroidveins)directlyintotheinternaljugularveins,anddrainsinferiorlyintothebrachiocephalicveins.Thedominantlymphatic

6、drainageaccompaniesthevesselswithinthelooseareolarcarotidsheaths.Theveinsformaplexusonthesurfaceoftheglandwithintheareolarthyroid(visceral)fascia.Remainingexternaltothiscapsuleprovidesarelativelybloodlessdissection.Entryintothecapsuleisabloodymess.,ThyroidAnatomy4/13,Twocommonvariantsarethepresenceo

7、fapyramidallobeextendingupwardfromtheisthmusandathyroidimaarteryascendingfrombelow.Thepyramidallobeisaremnantofthetrackthethyroidfollowedinembryologiclifefromtheforamencecumatthebaseofthetongue,throughthesiteofthefuturehyoidbonetoitsfinallocation.Incompletedescentofthethyroidcanbemistakenforatumor.I

8、nthefaceofahighmidlineneckmass,itisimperativetodocumentthyroidtissueinthenormallocationbyscanbeforeexcision.Thethyroidimaarteryarisesfromanyofthegreatvesselsofthechestandneck.,ThyroidAnatomy2/13,Thearterialsupplytothethyroidcomesprincipallyfromthesuperiorandinferiorthyroidarteries.Theformerarisefrom

9、theexternalcarotidandthelatterareusuallyabranchofthethyrocervicaltrunkoffthesubclavianarteries.Theinferiorthyroidarteriespassbehindthecommoncarotidstoreachthelowerthirdofthethyroidglandoneachside.Notethepositionsofthevagusandrecurrentlaryngealnerves(detailsinsubsequentimages,ThyroidAnatomy3/13,Theth

10、yroidglandisthmussaddlesoneortwooftheuppermosttrachealringsandusuallyblocksthesiteofanoptimaltracheostomy.Itisroutinelydividedinsuchcases.Thelobesoftheglandwrapposteriorlytoembracetheuppertracheaandlowerlarynx.Theposteriorfaceofeachlobeliesonthecarotidsheath(seealsoneckanatomy).,ThyroidAnatomy1/13,T

11、hethyroidglandisenclosedinathinlayerofpretrachealorvisceralfasciawhichalsoincludesthetracheaandesophagus.Thevisceralcompartmentoftheneckisdeeptotheintermediatefasciasurroundingthestrapmusclesandtheinvestingfasciaenclosingthesternocleidomastoidandtrapeziusmuscles(seeneckanatomyimages).Behindtheviscer

12、alcompartmentistheprevertebralfasciaoverlyingthecervicalvertebrae(seebrachialplexusanatomy).Thespacebetweentheesophagusandprevertebralfasciaextendsdownintothemediastinum.Therecurrentlaryngealnerveisinthetracheoesophagealgrooveoranteriortoitinthemajorityofindividuals(detailsinsubsequentimages).,Thyro

13、idAnatomy5/13,Thelarynxisinnervatedbybranchesofthevagusnerve(cranialnerveX).Allthemusclesofthelarynxexceptthecricothyroid(seelarynx)aresuppliedbytherecurrentlaryngealnerves.Theterminalportionofthisnervepassesbeneaththeinferiorpharyngealconstrictortoenterthelarynxbehindthearticulationoftheinferiorcor

14、nuofthethyroidcartilagewiththecricoidcartilage.Recurrentlaryngealnerveinjuryresultsinparalysisofthevocalcordinarelativelyadductedposition.Bilateralrecurrentnerveinjuryduringtotalthyroidectomymayresultinacutepostoperativeairwayobstruction.Itisimportanttodopre-andpostoperativelaryngoscopytodocumentvoc

15、alcordfunction.Thesuperiorlaryngealnervearisesfromthenodoseganglionofthevagusjustoutsidethejugularforamenatthebaseoftheskullandpassesdiagonallydownwardclosetothesidesofthelarynx.Itsendsasensorybranchthroughthethyrohyoidmembraneandcontinuesasamotorbranchtothecricothyroidmuscleandinferiorconstrictor.T

16、hecricothyroidmusclemaintainstensiononthevocalcords.Injurytothesuperiorlaryngealnerveresultsinlossoftimbre,enduranceandhighrangesingingcapability.,ThyroidAnatomy6/13,Therecurrentlaryngealnerveontherightarisesfromthevagusatthelevelofthesubclavianartery,passesbeneaththearteryandascendsnearthetrachea-e

17、sophagealgroove(seebelow).TheleftrecurrentlaryngealarisesattheleveloftheaorticarchandpassesbeneaththeaortajustdistaltotheligamentumarteriosumandalsoascendsneartheleftT-Egroove,ThyroidAnatomy7/13,Rarely,oneofthelaryngealnervesisnotrecurrentbuttakesastraightcoursetothelarynxfromabove.Thishappenswhenan

18、aorticarchdevelopmentalanomalyresultsinaberranttakeoffofasubclavianarteryfromthedistalarch.Theconditionisrareandusuallyinvolvesanaberrantrightsubclavianartery(lessthan1%ofthepopulation)passingposteriortotheesophagus.Inthatcasetherightnerveisnon-recurrent.Compressionoftheesophagusiscalleddysphagialusoria.Veryrarely(1in2000),thereisarightsidedaorticarchwithamirrorimageanomalyresultinginanon-re