甲状腺的解剖

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

2、desanexcellentplaneofdissectionexposingthedeepfasciaoftheneck.BecauseoftheinvertedV-shapedgapinthislayeranteriorly,dissectionofflapsinacollarincisionshouldbeginlaterally.ThyroidAnatomy11/13Thesternocleidomastoidmusclesflankthestrapsandcovertheinternaljugu

3、larsandcarotidsheaths.Theyareenclosedinanencirclinggirdleofdeepcervicalfasciacalledtheinvestinglayer.Thislayercontinuesposteriorlytoenclosethetrapeziusmuscles(seeneckclinicalfolio).Theexternaljugularveinsdescendacrosstheposteriorportionsofthesternocleidom

4、astoidsandanteriorjugularveinsdescendalongthestrapsanteriorly.ThyroidAnatomy10/13Thethyroidiscoveredbythesternohyoidandsternothyroid(strap)muscles.Theseareenclosedinanintermediatelayerofdeepcervicalfascia(seeThryoidAnatomy:1)withthesternohyoidsbeingappose

5、dinthemidlineandtheunderlyingsternothyroidsbeingslightlymorelateral.Whenmobilizingthestrapsitisimportanttostayintheplanedeeptobothmuscles.Theomohyoidmusclesascenddiagonallyacrosstheupperpartofthestrapsandareautomaticallymobilizedwiththosemuscles.ThyroidAn

6、atomy9/13Venousdrainageofthethyroidrunswiththesuperiorlaryngealarteriesabove,passeslaterally(middlethyroidveins)directlyintotheinternaljugularveins,anddrainsinferiorlyintothebrachiocephalicveins.Thedominantlymphaticdrainageaccompaniesthevesselswithinthelo

7、oseareolarcarotidsheaths.Theveinsformaplexusonthesurfaceoftheglandwithintheareolarthyroid(visceral)fascia.Remainingexternaltothiscapsuleprovidesarelativelybloodlessdissection.Entryintothecapsuleisabloodymess.ThyroidAnatomy4/13Twocommonvariantsarethepresen

8、ceofapyramidallobeextendingupwardfromtheisthmusandathyroidimaarteryascendingfrombelow.Thepyramidallobeisaremnantofthetrackthethyroidfollowedinembryologiclifefromtheforamencecumatthebaseofthetongue,throughthesiteofth