The courses and distributions of the lingual nerve in the ventral tongue region; Anatomical consideration for frenectomy Yong-Je Woo, D.D.S. Department of Dentistry The Graduate School, Yonsei University The courses and distributions of the lingual nerve in the ventral tongue region; Anatomical consideration for frenectomy Directed by Professor Hee-Jin Kim, D.D.S., Ph.D. The Master's Thesis submitted to the Department of Dentistry, the Graduate School of Yonsei University in partial fulfillment of the requirements for the degree of Master of Dentistry Yong-Je Woo, D.D.S. December 2008 This certifies that the Master's Thesis of Yong-Je Woo is approved. ---------------------------------------------------------------- Thesis Supervisor : Prof. Hee-Jin Kim ---------------------------------------------------------------- Thesis Committee Member : Prof. Kyung-Seok Hu ---------------------------------------------------------------- Thesis Committee Member : Prof. Ki-Seok Koh The Graduate School Yonsei University December 2008 ACKNOWLEDGEMENTS 본 논문이 완성되기 까지 부족한 저를 항상 격려해주시고 사랑과 관심으 로 이끌어주신 김희진 교수님께 깊은 감사를 드립니다. 또한 많은 격려와 지도 편달을 해주신 고기석 교수님께도 감사를 드립니다. 또한 본 연구내내 많은 도움을 아끼지 않으신 허경석 교수님과 치과대학 구강생물학교실 해부학교실원들께도 감사의 인사를 드립니다. 주위에서 저를 항상 응원해 주시고 보살펴주신 부모님과 장인, 장모님께 감사드리며 마지막으로 사랑하는 나의 아내 윤정, 예쁜딸 예원, 그리고 어 제 극적으로 태어난 둘째 아들에게 진정으로 사랑과 고마움의 마음을 전합 니다. 모든 분들께 진심으로 감사드립니다. 2008 년 12 월 저자 씀 TABLE OF CONTENTS LIST OF FIGURES ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ⅱ LIST OF TABLES ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ ⅲ ABSTRACT ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ iv Ⅰ. INTRODUCTION ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 1 Ⅱ. MATERIALS AND METHODS ‥‥‥‥‥‥‥‥‥‥‥‥ 4 1. Materials ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4 2. Methods ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 4 Ⅲ. RESULTS ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 7 Ⅳ. DISCUSSION ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 15 Ⅴ. CONCLUSION ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 18 REFERENCES ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 19 ABSTRACT (In KOREAN) ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 24 - i - LIST OF FIGURES Figure 1. Classification of the course of the lingual nerve (LN) into five patterns. ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 5 Figure 2. Five patterns of the proceeding course of the lingual nerve (LN). ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 8 Figure 3. The twigs (TM) directly innervating to the vental of the the tongue. ‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥‥ 12 Figure 4. The innervation of the LN to the tongue which was visualized by modified Sihler's nerve staining. ‥‥‥‥‥‥ 14 - ii - LIST OF TABLES Table 1. The innervation of the LN to the tongue which was visualized by modified Sihler's nerve staining ‥‥‥‥‥‥ 11 Table 2. Asymmetry of the anatomical patterns of the lingual nerve between right and left side ‥‥‥‥‥‥‥‥‥‥‥ 13 - iii - Abstract Thecoursesanddistributionsofthelingual nerveintheventraltongueregion;Anatomical considerationforfrenectomy YYYooonnnggg---JJJeeeWWWooooooDDD...DDD...SSS... DepartmentofDentistry TheGraduateSchool,YonseiUniversity (DirectedbyProfessorHee-JinKimD.D.S.,Ph.D.) Theaimofthisstudywastoelucidatetheintra-andsub-lingualcourseof thelingualnerve(LN)attheventraltongueregionandtoserveastheclinical guidanceforsafesurgicalproceduressuchasfrenectomy.We evaluated sixteenspecimensbymeansofgrossobservationafterdetaileddissections,and sixspecimensvisualizedbySihler'sstaining.Allspecimenswereharvested fromtheembalmedKoreancadavers.Weclassifiedtheproceedingpatternsof theLN into5 typesandconfirmedthedistributionoftheLN onthetongue tip.TheclassificationoftheLNwasmadewithreferencetothelineinwhich thestyloglossus(SG)andgenioglossusmuscle(GG)interlaced.Basedonthe courseofLN andtheexistenceofthetinytwigdirectlyinnervatingtothe sublingualmucosa(TM),theLN wasclassifiedintostraight,curvedand verticalpatternwithorwithouttheTM.WithouttheTM,Shown werethe straightpatternin9.4%,curvedpatternin46.9%andverticalpatternin18.8%. NothavingtheTM,thestraightpatternandcurvedpatternwas presentin 6.3%andin18.8%,repectively.TheresultsfromtheSihler'sstaininganalysis demonstratedthattheregionofthetonguetipwasinnervatedbytheLN.The - iv - presentstudyproposedthatsurgicalmanipulationsattheventraltongueregion maydamagetheLN andresultinnumbnessthetonguetipandprovided usefulanatomicalreferenceforthevarioussurgicalproceduresattheventral tongueregion. ∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲∲ Key words : lingualnerve,tongue tip,lingualfrenulum, frenectomy, frenuloplasty,Sihler'sstaining - v - Thecoursesanddistributionsofthelingual nerveintheventraltongueregion;Anatomical considerationforfrenectomy YYYooonnnggg---JJJeeeWWWooooooDDD...DDD...SSS... DepartmentofDentistry,TheGraduateSchool, YonseiUniversity (DirectedbyProfessorHee-JinKimD.D.S.,Ph.D.) ⅠⅠⅠ ...IIINNNTTTRRROOODDDUUUCCCTTTIIIOOONNN Thelingualnerve(LN) isoriginatedfrom theposteriortrunk ofthe mandibularenerveandcarriesgeneralsensationfrom theanteriortwo-thirds ofthetongue,thelingualmucosaontheflooroftheoralcavity andlingual gingivaassociatedwiththelowerteeth(HeasmanandBeynon,1986).After passing through the infratemporalfossa and proceeding between the mandibularramusandthemedialpterygoid,theLNentersintothetongueon thelateralsurfaceofthehyoglossusmuscle(HG)(Kimetal.,2004).Nerve twigsoftheLNreachthetipofthetonguesupplyingafferentnervefibersto theventralregionofthetongue(Standring,2005;Saigusaetal.,2006). Injurytothelingualnerveoftenoccursduringextractionofthethird - 1 - molar,localanesthesia,orthognathicsurgery,preprostheticsurgery,tumor excision,orfacemaskventilation(McGeachie,2002;Graff-RadfordandEvans, 2003;Kimetal.,2004;Brimacombeetal.,2005;SmithandLung,2006; Tolstunov,2007).Hence,theanatomicalstudiesoftheLN mainlyhavebeen focusedoncoursesattheregionsofthemouthfloorandtheretromolar trigonewhicharesusceptibletoinjuryduringthesemanipulations(Lauretano etal.,1997;McGeachie,2002;Graff-RadfordandEvans,2003;Kimetal., 2004).However,itisnecessaryforperformingsafetysurgicalproceduressuch asfrenectomy and partialglossectomy fortheankyloglossia (tongue-tie), macroglossiaortongue cancertorecognizeanatomy ofthe sub- and intra-lingualcourseandpositionoftheLNattheventralregionofthetongue comprisingthelingualfrenulum.(Tantawi,1969;Allisonetal.,1971;Winstock andWarnakulasuriya,1986;Herrenetal.,1989;Wright,1995;Garciaetal. 2002;LalakeaandMessner,2003;Fiorottietal.,2004;Gallegos-Hernandezet al.,2004;Queiroz,2004;HallandRenfrew,2005;Hellerand Gabbay,2005; Ostapiuk,2006;WallaceandClarke,2006;Segaletal.,2007;Wangetal., 2008).Therearesome descriptionsofthelingualinnervationsusing by classicalmethodssuchasgrossanatomicaldissectionincadavericstudies, neuraltracingtechniquesandelectrophysiology(El-Malek,1938;Lawn,1966; Yamamoto,1975;Loew,1980).However,fewdetailedneuroanatomicaldepiction hasnotbeendemonstratedfortheLNattheventraltongueregion,regarding thesesurgicalinterventions.Furthermore,itisdifficulttodissecttheLN in theirintra-lingualdistributionswithoutmarkedmodificationofthecourseof thenervebranches(Zuretal.,2004;Toureetal.,2005).WhereasSihler’s nerve staining makeswholespecimens translucentwhilecounterstaining nerves,andhenceadetailedviewofthenervebranchesandtheirendscanbe examinedwithoutthemodificationsofthecoursesofthenervebranches (Sandersetal.,1993;Mu andSanders,1996;Mu andSanders,1998;Mu and - 2 - Sanders,1999). In thisstudy,investigations were performed elucidating sub- and intra-lingualtopographyoftheLNattheventraltongueregiontoserveasa referenceofvarioussurgicalinterventionsbymeansofthe grossanatomical observationandSihler'snervestaining. - 3 - ⅡⅡⅡ ...MMMAAATTTEEERRRIIIAAALLLSSS &&& MMMEEETTTHHHOOODDDSSS 1.Materials Twenty-twospecimensoftonguewereusedinpresentstudy(12males,10 females;average69.0ageyears)andtheywereharvestedfrom theembalmed Koreancadavers.GrossanatomicaldissectionsweremadeontheLN in16 specimens.Nervestainingwasperformedonsixspecimensinaccordancewith modifiedSihler'sstainingmethod. 2.Methods A.Proceedingpatternsofthelingualnerve Thesublingualmucosawasdelicatelystrippedoffintheventraltongue regionand connectivetissuewasremovedbya detaileddissectionfor identifyingthetopographyoftheLN,HG,SG andSS.Thereferenceline (S-G line)wasestablishedwheretheSG andtheSS interlaced andthe referencepoint(Tpoint)wassetonthepointwheretheS-Glineoftheeach sidemet.Theclassificationwasmadeaccordingtothecourse ofthemost medialbranchoftheLN(mLN)attheventraltongueregionandthepresence ofthenervetwigsoftheLNdirectlyinnervatingtothelingualmucosa(TM). Therightandleftsidesofthespecimenwereseparatelyregardedasan independentobservationobject.Oncompletionofthedissection,thetopography ofthemLNwasclassifiedintofivetypesasfollows(Fig.1). TypeⅠa:mLNproceedingstraightalongtheS-Lline,nothavingtheTM. TypeⅠb:mLNproceedingstraightalongtheS-Lline,baringtheTM. TypeⅡa:mLNproceedingcurvedlywithadistancefromtheS-L line,not havingtheTM. TypeⅡb:mLNproceedingwithacurvedkeepingadistancefrom theS-L - 4 - line,baringtheTM. TypeⅢ:mLN proceedinganteriorlyontheSG,andascendingvertically nearthemidline,nothavingtheTM. Fig.1.Classificationofthecourseofthelingualnerve(LN) intofive patterns.A,TypeⅠa;B,TypeⅠb;C,TypeⅡa;D,TypeⅡb;E,TypeⅢ. B.PreparationofSihler'sstainingforelucidatingtheinnervationsatthe tonguetip Modified Sihler’snerve staining technique was performed for the - 5 - observationofthenervedistributionattheventraltongueregion(Fig.4).10% unneutralizedformalinwasinjectedthroughbloodvessels forfixationofthe muscles(fixation).Fixedmuscleswerewashedusingirrigationwater,and depositedin3%aqueouspotassiumhydroxidesolutionwithadditionof0.2ml of 3% hydrogen peroxide solution for 4 weeks (maceration and depigmentation).Onepartglacialaceticacid,onepartglycerin,andsixparts of1% aqueous chloralhydrateconstituted the Sihlersolution I.After maceration,musclesweretransferredintoSihlersolution I (decalcification). Sihler’ssolutionIIwascomposedofonepartEhrlichhematoxylin,onepart