ANATOMYOFTHEVOICE

ANATOMYOFTHEVOICEAnIllustratedGuideforSingers,VocalCoaches,andSpeech

Therapists

THEODOREDIMON

Illustratedby

G.DAVIDBROWN

NorthAtlanticBooksBerkeley,California

Copyright©2018byTheodoreDimon.Allrightsreserved.Noportionofthisbook,exceptforbriefreview,maybereproduced,storedinaretrievalsystem,ortransmittedinanyformorbyanymeans—electronic,mechanical,photocopying,recording,orotherwise—withoutthewrittenpermissionofthepublisher.ForinformationcontactNorthAtlanticBooks.

PublishedbyNorthAtlanticBooksBerkeley,California

CoverartandallillustrationsbyG.DavidBrownCoverdesignbyHowieSeverson

AnatomyoftheVoice:AnIllustratedGuideforSingers,VocalCoaches,andSpeechTherapistsissponsoredandpublishedbytheSocietyfortheStudyofNativeArtsandSciences(dbaNorthAtlanticBooks),aneducationalnonprofitbasedinBerkeley,California,thatcollaborateswithpartnerstodevelopcross-culturalperspectives,nurtureholisticviewsofart,science,thehumanities,andhealing,andseedpersonalandglobaltransformationbypublishingworkontherelationshipofbody,spirit,andnature.

MEDICALDISCLAIMER:Thefollowinginformationisintendedforgeneralinformationpurposesonly.Individualsshouldalwaysseetheirhealthcareproviderbeforeadministeringanysuggestionsmadeinthisbook.Anyapplicationofthematerialsetforthinthefollowingpagesisatthereader’sdiscretionandishisorhersoleresponsibility.

NorthAtlanticBooks’publicationsareavailablethroughmostbookstores.Forfurtherinformation,call800-733-3000orvisitourwebsiteatwww.northatlanticbooks.com.

e-ISBN978-1-62317-198-8

LibraryofCongressCataloging-in-PublicationData

Names:Dimon,Theodore,Jr.,author.|Brown,G.David,illustrator.Title:Anatomyofthevoice:anillustratedguideforsingers,vocalcoaches,andspeechtherapists/TheodoreDimon;illustratedbyG.DavidBrown.

Description:Berkeley,California:NorthAtlanticBooks,[2018]|Includesindex.Identifiers:LCCN2017046674|ISBN9781623171971(tradepaper)Subjects:|MESH:Larynx—anatomy&histology|Larynx—physiology|WorkofBreathing|VoiceClassification:LCCQP306|NLMWV501|DDC612.2/33—dc23LCrecordavailableathttps://lccn.loc.gov/2017046674

NorthAtlanticBooksiscommittedtotheprotectionofourenvironment.WepartnerwithFSC-certifiedprintersusingsoy-basedinksandprintonrecycledpaperwheneverpossible.

TABLEOFCONTENTS

LISTOFILLUSTRATIONS

INTRODUCTION

1.THEANATOMYOFBREATHINGTheSpineandRibCageJointsoftheRibsActionoftheRibsIntercostalMusclesTheDiaphragmActionoftheDiaphragmDiaphragmandAbdominalCavityTheAbdominalMusclesAuxiliaryMusclesofBreathingExtensorandFlexorSupportoftheTrunkTheLungsandTracheaLungCapacity

2.THELARYNXBasicStructureoftheLarynxTheFrameworkoftheLarynxTheEpiglottisCricoarytenoidJointCricothyroidJointConusElasticusTheInterioroftheLarynxMusclesoftheEpiglottisTheStructureoftheVocalFolds

IntrinsicMusclesoftheLarynxActionsoftheIntrinsicMusclesoftheLarynxCricothyroidandThyroarytenoidAntagonismActionoftheLarynxMusclesinChestRegisterActionoftheLarynxMusclesinFalsettoRegisterActionoftheLarynxMusclesinHeadRegister

3.THEEXTRINSICMUSCLESOFTHELARYNXTheSuspensoryMusclesoftheLarynxActionoftheSuspensoryMusclesduringSingingSupportedFalsettoHeadVoiceTheHyoidApparatusSidebar:TheHyoidBoneMusclesoftheHyoidBoneandJaw

4.THEMOUTHANDPHARYNXMusclesoftheMouthandThroatTheFunctionofthePalateTheMusclesofthePalateSidebar:TheActionofSwallowing(Deglutition)TheArchedPalateTheTongueandItsFunctionPositionoftheTongueinSingingTheLowLarynxandWidenedPharynx

5.THEFACEANDJAWTheMaskTheNostrilsandNasalCavityMusclesoftheNostrilsTheEyesandForeheadTheCheeks

TheJawandTemporomandibularJointPositionoftheJawinSingingMusclesoftheJaw

6.THEEVOLUTIONANDFUNCTIONOFTHELARYNXTheOriginoftheLarynxEvolutionoftheCartilagesandMusclesoftheLarynxExtrinsicMusclesoftheLarynxandDeglutitionThePalate,Epiglottis,andNasalPassagesDesignoftheVocalFoldsThePharynx,UprightPosture,andHumanSpeech

EPILOGUE

INDEX

ABOUTTHEAUTHOR

LISTOFILLUSTRATIONS

1.THEANATOMYOFBREATHING1-1.Movementoftheribcage1-2.Movementofthediaphragm1-3.Ribcageandspine1-4.Diaphragmaspartitionbetweenthoracicandabdominalcontents1-5.CostovertebralorribjointofT51-6.Typesofribs1-7.Ribsmovelikethehandlesofapail1-8.Actionofribatjoint:a.Sagittalsectionofribjoint;b.Rangeofmotion

ofrib1-9.Externalandinternalintercostalmuscles1-10.Levatorescostarum,levatorcostae,andquadratuslumborum1-11.Transversusthoracismuscle1-12.Thediaphragm1-13.Diaphragmshowingplacementofheartontop,aswellasviscera

below,whicharepusheddownininhalation1-14.Frontandsideviewsofdiaphragmanditsmovementsduringbreathing1-15.Diaphragmdescending1-16.Diaphragmdescendingandribsascending1-17.Actionofdiaphragminrelationtoribmovement(assistinginelevating

ribs)1-18.Intercostalsandobliquesoftrunk1-19.a.Externalabdominalobliquemuscle;b.Internalabdominaloblique

muscle;c.Transversalis1-20.Rectusabdominismuscle1-21.Sternocleidomastoidmuscle1-22.Scalenemuscles1-23.a.Deepposturalmuscles;b.Sacrospinalisgroup

1-24.Flexorsupportofsternocleidomastoidandrectusabdominismuscles1-25.Thirdlayer:serratusmuscles1-26.Fourthlayer:scapulamuscles1-27.Fifthlayer:trapeziusandlatissimusdorsi1-28.Thelungsandtrachea1-29.a.Totallungcapacity;b.Lungcapacityinrelaxedstate

2.THELARYNX2-1.a.Vocalfoldsopen;b.Vocalfoldsclosed;c.Vocalfoldsapproximated

forphonation2-2.Cartilagesandvocalfolds2-3.Theframeworkofthelarynx2-4.Thyroid,cricoid,andarytenoidcartilages2-5.Cricoarytenoidjoint:a.Articularfacetsoncricoid;b.Movementof

arytenoidcartilagesonthecricoidcartilage2-6.Cricothyroidjoint2-7.Conuselasticus2-8.Theinteriorofthelarynx2-9.Thearyepiglotticmuscleoftheepiglottis2-10.Thethyroepiglotticmuscleoftheepiglottis2-11.Cricothyroidmuscle2-12.Vocalisandthyroarytenoidmuscles2-13.Theglottis.2-14.Theposteriorcricoarytenoidmuscle2-15.Thelateralcricoarytenoidmuscle2-16.Thetransverseandobliquearytenoidmuscles2-17.Actionoftheposteriorcricoarytenoidmuscles,theopeners2-18.Actionofthelateralcricoarytenoidmuscles,whichclosetheglottis2-19.Actionoftransverseandobliquearytenoidmuscles,whichclosethe

glottis2-20.Thecricothyroid,astretchingmuscle2-21.Stretchingofthevocalfolds

2-22.Tensorsofthelarynx2-23.Waveactionofthevocalfolds2-24.Vocalfoldsinchestvoice2-25.Vocalfoldsinfalsetto

3.THEEXTRINSICMUSCLESOFTHELARYNX3-1.Suspensorymusclesofthelarynx3-2.Baseofskullwithstyloidandmastoidprocess3-3.Completesuspensorymusclesofthelarynx3-4.a.Elevationoflarynxinsinging;b.Strainedappearanceofsinger;c.

Linesofforceoftheelevators3-5.Actionofthesuspensorymusclesduringsinging3-6.Actionofsuspensorymusclesinsupportedfalsetto3-7.Actionofsuspensorymusclesinheadvoice3-8.Hyoidapparatus3-9.Styloidprocessandhyoidbone3-10.Completehyoidmuscles3-11.Falseelevatorsoftongue3-12.Thestrapmuscles

4.THEMOUTHANDPHARYNX4-1.Thevocaltract4-2.Thearticulators4-3.Musclesofthemouthandthroat4-4.Constrictorsofthethroat4-5.Valveactionofthepalate:a.Velopharyngealclosureofsoftpalate

againstbackofpharynx;b.Oralsealformedbybackoftonguecontactingsoftpalate;c.Bothactionscombiningtosealnasalandoralpassages

4-6.Elevatorsofthepalate4-7.Depressorsofpalate4-8.Thesoftpalate:a.Arched;b.Depressed4-9.Thetongueanditsmuscles

4-10.a.Positionofthetongueduringsinging:openthroat;b.Raisedpositionoftongue:closedthroat

4-11.Positionofthetongueinvowelformation4-12.a.Raisedlarynxandconstrictedthroat;b.Loweredlarynxandopen

throat

5.THEFACEANDJAW5-1.Musclesoftheface5-2.Themask5-3.Nasalcavity5-4.Musclesofthenose5-5.Musclesoftheeyesandforehead5-6.Musclesofthecheekandmouth5-7.Thejawandtemporomandibularjoint5-8.a.Partialopeningofthejawforspeaking:hingeaction;b.Wider

openingofthejawforsinging:hingeandglidingaction5-9.Musclesofthejaw5-10.Depressorsofthejaw5-11.Thediaphragmofthejaw

6.THEEVOLUTIONANDFUNCTIONOFTHELARYNX6-1.Thelarynxfunctionsasasphinctertocloseofftheairway6-2.Sphinctermusclesanddilator6-3.Themusclesthatdilateandclosetheairway6-4.Palateandseparationofnasalandoralpassageway:a.Reptile;b.

Mammal6-5.Epiglottisandpalateinherbivoreshowinghowtheepiglottislinkswith

thepalatetocloseoffmouthtobreathing6-6.a.&b.Coronalviewoflarynxshowinginletandoutletvalves

(ventricularbandsandvocalfolds);c.Thevocalfoldsdonotopposetheoutflowofairandvibratetoproducesound

6-7.Pharynxasresonatorin:a.Apes;b.Man

TINTRODUCTION

hisbookhasbeenwrittenasareferenceforsingers,vocalcoaches,speechtherapists, and students of voicewho require detailed information on the

anatomyof thevoiceandhow itworks.Althoughmanybooksonsingingandspeech are currently available, very few of them actually present the basicanatomyof thevoiceinclearandsimpleterms,whichis theaimofthiswork.Readers familiarwithmy first bookon thevoice,YourBody, YourVoice,willknow that I have already presented a new approach to the subject of voiceproduction.Thisnewbookcomplementsthefirstvolume,inwhichthebasicsofanatomyofthevoicewerenotincluded.

Incompilingbasicanatomicalinformationonthevoice,thefirstquestionthatarisesiswhattoinclude.InthisbookIhaveidentifiedfivebasicsystemsthatareresponsibleforvocalproduction:

Thefirst,andinmanywaysthemostbasicpartofthevoice,istherespiratorysystem.Although sound is produced in the larynx, thiswould not be possiblewithouttheflowofairfromthelungs.Thisairflowprovidesanecessarypowersourcetosetthevocalcordsintomotiontoproducesound.InChapterOnewe’lllookattheanatomyofbreathing.

Chapter Two examines the second system, the larynx, which is the mostimmediatephysicalstructurepertainingtothevoice.Itsroleinvocalproductionanditshighlyspecializedfunctionsaresoimportantthatitmeritsakeyplaceinabasicanatomicalreferenceonthevoice.Thelarynxformsthehousingforthevocalfoldsthatvibratetomakesound,bringingthemtogetherwhenwewanttospeak or sing, and pulling them apartwhenwe breathe normally. Though theintricatedesignof the larynxdoesnot lend itself toeasycomprehensionof itsfunction,whenwebreakdownitscomponentpartsandlookattheminturn,itbeginstomakesense.

Thelarynxitselfissuspendedwithinanetworkofmuscles—sometimescalledtheextrinsicmusclesof the larynx—thatmove thestructurewhenweswallowand help it to function. These constitute the third system we will examine.Althoughtheroleofthesemusclesinswallowingiswellunderstood,theirrole

invocalizationhasbeen largelymisunderstoodandunderestimated.We’ll lookatthefunctionofthesemusclesinChapterThree.

The fourth basic system is the vocal tract,which ismade upmainly of thepharynxbutalsoincludestheoralcavityandthepositionofthelarynx.Itisherethatwebreakupthesoundscomingfromthelarynxintospeech.Itisalsoherethat the sound from thevibratingvocal folds is augmented.Because thevocaltract is not fixed in shape but can be altered by how we use the differentstructuressuchasthemouth,tongue,andpalate,itformsacrucialpartofvocaltraining.We’lllookattheseelementsindetailinChapterFour.

Because the face also occupies a practical role in vocal training, I haveincludedafifthchapterdescribingthemusclesofthefaceastheyrelatetovocalplacement.HereIhavealso included the jaw,since itnaturallybelongs in thissection.

Inthefinalchapterwewilllookatthefunctionandevolutionofthelarynxinparticular,andthevoiceingeneral.Becausethelarynxissocomplex,itisnearlyimpossible to appreciatewhy it is theway it iswithout having some sense ofhow it evolved, which in turn helps to make some of its features moreunderstandable.

B

CHAPTER1

THEANATOMYOFBREATHING

reathing is one of the most vital of our life processes. All day long,throughoutourlives,wetakeinairinordertoprovidecellsthroughoutthe

bodywithoxygenandthenexpelcarbondioxidefromthelungsinordertoridthe body ofwastes produced by cellular activity. Secondarily, breathing is thepowersourcethatsetsthevocalfoldsintomotiontoproducesound.Todothis,wedonotexhalenormallybutalterourbreathingso thatwecanproduce thesustainedsoundsofspeechandsong.

Although breathing refers to the flow of air into and out of our bodies, weactuallybreathebyalteringthesizeofourchestcavity,notbydoingsomethingtotheair.Bymakingthespacewithinthechestcavitygetlargerandsmaller,airflows into and out of the chest through either the nose ormouth. That simpleexchangeofairiswhatwecallbreathing.

Therearetwowaysthatweincreaseanddecreasethesizeofthechestcavity.First,theribs,whichformthechestcavity,arecapableofrisinglikepailhandlesbymovingatthejointswheretheyattachtothespine;thisactionincreasesthespace within the chest (Fig. 1-1). The uppermost ribs connect in front to thesternum;thosebelowformanarchbeneathit;thelasttwo,thefloatingribs,donotattachinfront.Becauseofthis,notalltheribsmoveinthesameway,ortothesamedegree.Butmostoftheribsriseandwidentosomeextent,makingthespaceinsidethechestlarger;whentheyreturntotheirlowerposition,thespacegetssmaller.

Figure1-1.Movementoftheribcage.

Second, the bottom of the thoracic cavity is separated from the abdominalcontents below by the dome-like muscle of the diaphragm, which, bycontracting, can flatten out and thus increase the size of the lower part of thechestcavity(Fig.1-2).Whentheribsriseandopen,thediaphragmcontractsanddescends;thechestcavityincreasesandairrushesintofillthelungs.Whentheribsreturntonormalposition, thediaphragmrelaxesandascends,air isforcedout,andweexhale.

Figure1-2.Movementofthediaphragm.

TheSpineandRibCage

Thebasic framework for the respiratory system is the spine and rib cage.Thespineismadeupoftwenty-fourvertebrae—fiveinthelumbarregion,twelveinthethoracic,andseveninthecervical.Thereisariboneachsideofthetwelvethoracicvertebrae,formingtheribcage(Fig.1-3).

Figure1-3.Ribcageandspine.

Therearetwelveribsoneachsideofthebodythatcorrespondtothetwelvethoracicvertebraeofthespine.Thefirstsevenattachinfronttothesternum,or

breastbone; these are called true ribs. The remaining five are called false ribsbecausetheydonotattachdirectlytothesternum,butjoineachothertoformanarchcalledthecostalarch,whichcanbeeasilyfeltbelowthesternum.Thefinaltworibsarecalledthefloatingribsbecausetheydonotattachinfront.Theribsattachingtothesternumandthecostalarcharenotbonyallthewayaround.Attheir extremity the bone becomes cartilage, so that the connection of the ribswith the sternum and the costal arch is cartilaginous and quite flexible. Thecostalarchisalsomadeupofcartilage.

Within the rib cage are the lungs and heart. The heart sits right behind thelowerpartofthesternumandalittletotheleft;thelungsareoneithersideoftheheart. The diaphragm forms the lower boundary of the thorax (Fig. 1-4); theheartandlungslieabovethediaphragm,andalltheothermajorinternalorganslie below the diaphragm, which forms a boundary between these upper andlower regionsof the trunk.“Diaphragm” isactuallyadescriptive term that theGreeksgavetothismuscle:itmeans“apartitionwall.”

Figure1-4.Diaphragmaspartitionbetweenthoracicandabdominalcontents.

JointsoftheRibs

Each of the twelve ribs moves in relation to the spine, where they form thecostovertebral joints (Fig. 1-5). Each rib articulates with the spine in severalplaces.First,theheadoftheribarticulateswiththelowerpartofthebodyofonevertebra and the upper part of the one below it, as well as with the disc inbetween the two vertebrae. Second, the neck of the rib articulates with thetransverseprocessofthelowerofthesetwovertebrae.

Figure1-5.CostovertebralorribjointofT5.

The rib is firmly bound at each of these articulations by several ligaments,permittingalimitedrotationatthejointthatneverthelesstranslatesintoquitealotofmovementovertheentirelengthoftherib.Someoftheribshavesimplerarticulations, but the main thing to keep in mind is that the ribs actuallyarticulateatthespinetopermitthemovementsessentialtobreathing.

Atthefrontpartoftheribcagetheribsterminateandbecomecartilaginous.Thisallowsameasureofflexibilityinthefrontoftheribs.Thesectionswherebonebecomescartilageformglidingjointsthatpermittheribssomemovement

inrelationtothesternumsothatboththesternumandribshaveacertaindegreeofmovementinfrontastheribsriseandfall.

Theribsarenotallidenticalincharacter(Fig.1-6).Thetopmostribisshort,flat,andround.Weoftenthinkoftheupperribsasbeingalmostaslargeasthemiddleones.However,thetopmostrib,whichformstheopeningintothethorax,orthoracicinlet,isquitesmall—onlyathirdthewidthoftheshouldergirdle.Itis throughthisopeningthat thewindpipe,esophagus,andotherstructurespassfromtheneckdownintothechest.Thenextribislargerbutshapedratherlikethefirst.Goingdownward,theribsincreaseinlengthuntiltheseventhrib,afterwhich they begin to get smaller again. They also slant down obliquely,correspondingtothemusclesofthetrunk,whichalsoslantandspiralaroundthetrunk.Thefinaltwofloatingribs,whicharemuchshorterthantheonesabove,arevery flexible in theirmovementsbecause theydonotattach toanything infront;theirfunctionismainlytoprovideattachmentsforthediaphragm.

Figure1-6.Typesofribs.

Inback,theribsdonotextenddirectlytothesidestoformtheribcage;theyactually angle backward almost to the level of the spinous processes of thevertebrae.Thismeansthatthereisagapbetweenthespinousprocessesandtheposteriorpartoftheriboneitherside.Thisgapisfilledupwiththelongitudinalextensormuscles,whichgivethebackaflatappearance.

ActionoftheRibs

Themovementoftheribsiscrucialtobreathing.Becausetheribsslantdownatanobliqueangle,theyhangbelowthepointwheretheyarticulatewiththespine.Whenweinhale,theribs,byrotatingwheretheyarticulatewiththespine,movelikepailhandlesbeingraisedslightly(Fig.1-7).Thisrotationraisesthesidesofthe ribs,which increases the lateraldimensionof the thorax. It alsobrings thefrontoftheribforwardasitmovesupward,whichincreasestheanteroposteriordimensionsofthethoraxaswell(Fig.1-8).Thesemovementsincreasethespacewithinthethorax,causingair toflowintothelungs.Ofcourse,notall theribsmove in the sameway: the first ribsmove very little, and there is in generalmoremovementasyougo lowerdown.The final two floating ribs,whicharenot attached either directly or indirectly to the sternum, have even greatermobility.

Figure1-7.Ribsmovelikethehandlesofapail.

Figure1-8.Actionofribatjoint:a.Sagittalsectionofribjoint;b.Rangeofmotionofrib.

IntercostalMuscles

Thereare two layersof rib,or intercostalmuscles thataredirectly responsiblefor respiratorymovementsof the ribs inbreathing (Fig.1-9).Thereare elevenexternalintercostalmuscles,onebetweeneachofthetwelveribs.Theyoriginateatthelowerborderofeachribandattachtotheupperborderoftheribbelow,running obliquely down and forward. Underneath this layer are the eleveninternal intercostalmuscles that originate at the inner surface of each rib andslant down and back, in the opposite direction to the external intercostals, toattachtotheribbelow.

Figure1-9.Externalandinternalintercostalmuscles.

The external intercostals functionmainly to elevate the ribs, increasing thewidthofthethoraciccavityandcausinginspiration.Youcanseefromtheangleofthemusclewhattheeffectofcontractionwillbe.Whentheupperribsareheldor fixed inplaceby thescalenemusclesabove (seeFig.1-22), thecontractingfiberspullfromabovetoraisetheribsbelow,increasingtheoverallcapacityofthechest.

Conversely, the internal intercostals act in theoppositedirection,depressingtheribswhentheycontract,activelyfacilitatingbreathingout.

Thelevatorescostarumandlevatorcostaemusclesoriginateatthetransverseprocessesof thevertebraeand, runningobliquelydownward,attach to theribs below (Fig. 1-10). These muscles, as their name suggests, assist the

external intercostals in raising the ribs.When thequadratus lumborummuscleandlevatorescostarumarefunctioningproperly,thelowerbackbecomeselasticand filled out, and the floating ribsmove freely.This coordinated lengtheningandwidening in theback tends to lendgreatermobility to the ribs,whichcanthenexpandandmovemorefreely.

Figure1-10.Levatorescostarum,levatorcostae,andquadratuslumborum.

Thetransversusthoracismuscleliesontheinnersurfaceofthelowerpartofthesternum(Fig.1-11).Itsfibersextendupandout,likethesplayedfingersofahand,andinsertintothecostalcartilagesofthesecond,third,fourth,fifth,andsixthribs.Thismuscle,whichwhencontractedaidsinforcefulexpiration,isthemusclethatyoucansometimesfeelgrippingintheinnerchest;itcontributestothe rigidity of the chest in many people who raise and fix the chest whenspeakingandbreathing.

Figure1-11.Transversusthoracismuscle.

TheDiaphragm

Thediaphragmisthemainmuscleofbreathing(Fig.1-12).Itisalarge,dome-shaped muscle that divides the thoracic and abdominal cavities (as we sawearlier,theword“diaphragm”means“partitionwall”).Itsmuscularfibersarisefrom the anterior spine and the entire circumference of the lower thorax andconvergeupwardintoacentral tendinouspeakthatformstwodomesoneitherside of this central tendon. Its largest and lowest origin is a tendon called thecrus,whichoriginates fromboth sidesof the lumbar spine, so that themuscleappearstofanupwardfromthelowerspine.

Figure1-12.Thediaphragm.

Theotherportionsofthediaphragmarisefromatendonatthelowerpartofthe sternum, from the costal arch formed by the lowest six or seven ribs, andfrom a ligament that spans the lower back from the first or second lumbarvertebratothelowestfloatingrib.Fromthesepointsthemuscularfibersofthediaphragmascendinanarchtoformacentraltendinousaponeurosisatitstop.

The heart sits directly on top of the diaphragm, nestled between the lungs oneitherside.Thefibersofthepericardium,themembranethatenclosestheheart,intermingle with those of this central tendon so that the two are actuallyattached.Thecentral tendonalsoextends to thesides, forming the topofeachdome,sothatthecentraltendinoussheetonthetopofthediaphragmhasthreesections,orleaflets.

Becausethediaphragmformstheupperboundaryoftheabdominalregion,itquiteliterallysitsabovetheviscera—theliverontherightsideandthestomachand spleen on the left (Fig. 1-13). The shape of the diaphragm is actually adoubledome,therightdomebeinghigherthanthelefttoaccommodatetheliver,so that it appears as a somewhat lopsided mushroom. It is penetrated by theaorta,theesophagus,andthevenacava(thelargebloodvesselthatreturnsbloodtotheheart),whichpassfromthechestintotheabdominalregion.Thenormalrestingheightofthedomesofthediaphragmattheirhighestpointisroughlyonalevelwiththefifthrib.Duringdeepinhalation,thedomesdescendonetotwoinches,roughlytothelevelofthebottomofthesternum(seeFig.1-2).

Figure1-13.Diaphragmshowingplacementofheartontop,aswellasviscerabelow,whicharepusheddownininhalation.

ActionoftheDiaphragm

The diaphragm is an extremely active and hardworkingmuscle that contractsrhythmically every few seconds during normal breathing to ensure a constantsupply of air to the lungs. As we have seen, the entire top section of thediaphragm is composed of tendinous tissue and is therefore passive. Thecontractileportionof thediaphragmisformedbythemuscularfibers thatpassdownward from this central tendinous sheet around its entire circumference to

their origins around the circumference of the thorax. When the diaphragmcontracts,thesemuscularfiberstendtoflattenoutthecentraltendonanddrawitdownward; this increases the space in the lower thorax and causes air to flowinto the lungs(Figs.1-14and1-15).At the same time, the ribs ascend,whichalso contributes to the expansion of the spacewithin the chest cavity and theflow of air into the lungs (Fig. 1-16). Note that the active movement of thediaphragmisdownward,notupwardasmanypeoplemistakenlythink(perhapsbecausetheribsgoupininhalation).Thediaphragmdoesnotcontributetotheexhalationofairordirectly“support”thebreath;itreturnstoitshigherpositionasaresultoftheelasticrecoilofitsmuscularfibers.

Figure1-14.Frontandsideviewsofdiaphragmanditsmovementsduringbreathing.

LATERALVIEWS

Figure1-15.Diaphragmdescending.

Figure1-16.Diaphragmdescendingandribsascending.

During quiet or shallow breathing, the diaphragm descends about 1.5centimeters, or half an inch, and up to 6 or 7 centimeters, or two and a halfinches, during heavy breathing or forced inspiration. Because most of itsmovement takes place at the domes to either side of the central tendon, thecentraltendonitselfmoveslittleduringnormalbreathing.

DiaphragmandAbdominalCavity

Becausethediaphragmsitsontopoftheabdominalcavity,itsactionisaffectedbythecontentsof theabdomenandtheabdominalmuscles.Theabdomenactssomewhat likea flexible, fluid-filledcontainer.When thediaphragmcontracts,

its descent forces the contents of the abdomen outward, particularly if theabdomen is relaxed. If the abdominal muscles contract, however, the visceracannot move outward and the diaphragm is restricted in its downwardmovement.Thecentral tendonthenactsasafixedpointfromwhichthe lowerribs are pulled on by the contracting muscular fibers of the diaphragm, thuselevating them and expanding the lower thoracic cavity (Fig. 1-17). Theabdominalmusclescanthusassisttheactionofthediaphragm;however,singerswhoareoverlypreoccupiedwithgettingbreathorwhouseexcessiveefforttotryto support the breath can end up overworking the diaphragm,which becomeschronicallycontracted.Thishas theeffectover timeofdistending the ribsanddistortingthelowerribcage.

Figure1-17.Actionofdiaphragminrelationtoribmovement(assistinginelevatingribs).

Innormalbreathing,inhalationisactiveandexhalationispassive.Whenwebreathe in, the ribs are raised and the diaphragm actively lowers as musclecontractionoccurs.Whenwebreatheout, thethoracicwallsanddiaphragm,aswellastheexpandedlungtissue,elasticallyrecoilandpassivelyforceairoutofthelungs.Incontrast,whenweforcefullyexpelairfromthelungs,contractionoftheinternalintercostalsandtheabdominalmusclesactivelycompresstheribs,forcingtheairout.

During vocalization, muscles of both inhalation and exhalation are active.Whenwetakeairintothelungsandareabouttobreatheout,thetendencyforairtorushoutofthelungsissogreatthat,inordertocounterbalancethisforceandtoproduceacontrolledflowofairsuitableforphonation,inspiratoryforcesmustactively counterbalance passive recoil forces. To accomplish this, the internalintercostal muscles and diaphragm maintain tone and recoil slowly to theirrestingstateinordertocontroltheoutflowofair.Theactionofthediaphragmalso opposes the descent of the ribs, particularly if the exhalationmuscles areactively working to press air out. The diaphragm thus counteracts the out-breathing tendencybymaintaining the expansionof the ribs tohelp “support”thebreath.

The muscles of expiration also come into play in singing if the lungs andthorax have recoiled to their resting size and the singer still needs to producesound; in this case, abdominal and thoracic expiratory muscles are activelyemployedinhelpingtocontracttheribsandtopressthevisceraupagainstthediaphragm,thusexpellingmoreair.

TheAbdominalMuscles

The muscles in the abdominal region are continuous with those of the ribs,runningincorrespondingobliquedirections(Fig.1-18).Therearethreelayersofabdominal muscles, corresponding to the external and internal intercostalmuscles and the transversus thoracis, themuscle underlying the sternum. Theexternalabdominalobliquemuscleoriginatesat theeightlowestribs; itsfibersrun downward to attach to the rim of the pelvis, or iliac crest, and obliquelydownwardandforwardtoendinaponeurotic tissuethat terminatesat thelineaalba(Fig.1-19a).Thismuscleiscontinuouswiththeexternalintercostalmuscleofthethorax.

Figure1-18.Intercostalsandobliquesoftrunk.

Figure1-19.a.Externalabdominalobliquemuscle;b.Internalabdominalobliquemuscle;c.Transversalismuscle.

Theinternalabdominalobliquemuscleoriginatesattheinguinalligament,theiliaccrest,andthelumbarfascia(Fig.1-19b).Itsfibersfanouttoattachtothepubic bone, the linea alba, and the lower three ribs. It is continuouswith theinternalintercostalmuscleofthethorax.

The third and deepest muscle, corresponding to the transversus thoracismuscleofthechest,isthetransversusabdominis,ortransversalis(Fig.1-19c).Itoriginatesatthecrestoftheilium,thelumbarfascia,andtheribsandruns,asitsname suggests, horizontally around the midriff. It terminates in aponeurotictissue,joiningthelineaalbaandthepubicsymphysis.

Rectusabdominis is the longitudinalmusclevertically spanning the frontoftheabdomen(Fig.1-20).Itoriginatesatthepubicsymphysisandrunsverticallyupeachsideofthelineaalbaataslightlyoutwardangletoinsertintothefifth,sixth, and seventh ribs; it is enclosedwithina sheathof tendon formedby theoblique and transversalis muscles. By acting on the rib cage, this musclepowerfullycontractsorflexesthefrontofthebody(asinperformingasit-up);italsopowerfullycontractsthelowerpartoftheribcage.

Figure1-20.Rectusabdominismuscle.

Alltheabdominalmusclesareactivelyengagedduringforcefulexpirationofair.Duringvocalization,thediaphragmdoesnotrelaxallatoncebutmaintainstension so that air is released slowly; as we just saw, the abdominal musclesmaintain tensionof theabdominal cavity in conjunctionwith theactionof thediaphragm.

AuxiliaryMusclesofBreathing

There are several auxiliary muscles of breathing. The first is thesternocleidomastoidmuscle (Fig. 1-21), which originates by two heads at thesternum and clavicle and attaches to the mastoid process of the skull. Thismuscleisaflexoroftheheadandneck,andassistsinrotationofthehead.Likethe scalene muscles, it is considered an accessory muscle in breathing andnoticeablycontractsduringforcedinspiration.

Figure1-21.Sternocleidomastoidmuscle.

The scalene muscles, which originate from the transverse processes of the

cervical vertebrae and insert into the first two ribs, are also sometimesconsideredmusclesofrespiration.Theysupport theribsandcomeintoplay inforceful inhalation (Fig. 1-22). The upper ribs, however, do not actuallycontributemuchtobreathing,beingquitesquatandimmobile;thesemusclesactas tensile members or guy wires for supporting the rib cage from the upperspine, and in this sense they functionmore to provide tensile support for thebreathingapparatusthantoassistinbreathingitself.

Figure1-22.Scalenemuscles.

ExtensorandFlexorSupportoftheTrunk

Although the intercostal muscles are the prime movers of the ribs duringbreathing, the correct working of our overall upright support system is theessential foundationof coordinatedbreathing.This systemcanbedivided intothree functional groups of which the most important is composed of the two

deepest layers of posturalmuscles that support the trunk as awhole.The firstanddeepest layer is composedof the smallposturalmuscles that actupon thevertebrae along the entire lengthof the spine; their function is tomaintain theelongation and support of the spine. The second layer comprises thesacrospinalis or erector spinae muscles, which form large meaty bundlesattaching to the ribs and running vertically up the length of the spine. Theirfunctionistomaintaintheerectpostureofthetrunkbykeepingitfrombucklingforward.Theproperworkingof thesemusclesensures that the ribsareable tomove freely; if they are overly tense, their constriction will fix the ribs andinterferewithbreathing(Fig.1-23).

Figure1-23.a.Deepposturalmuscles;b.Sacrospinalisgroup.

Thesecondkeygroupofmusclesinouruprightsupportsystemiscomposedof the sternocleidomastoid muscle and other key anterior flexors such as therectus abdominis muscle, which provide tensile support for the thorax as awhole.Thesternocleidomastoidmuscleisacrucialsuspensorymusclefortheribcageandthefrontofthebody(Fig.1-24).Intheframeworkofthissupport,theintercostalsmaybeconsideredtheintrinsicmusclesofbreathing:theymaketheimmediateactionhappen,butfunctionproperlyonlyinthecontextofthelargersupport network of extensors and flexors that ensure the proper support andmobilityofthetrunkandribcage.

Figure1-24.Flexorsupportofsternocleidomastoidmuscleandrectusabdominismuscles.

The third group comprises the oblique muscles of the back and shouldergirdle, which enable the ribs to move because of their widening action. Thisgroup is composed of the third layer of back muscles (Fig. 1-25). Serratusposteriorsuperiororiginatesatthespinousprocessesofthelastcervicalandfirsttwo thoracic vertebrae and, inclining downward and outward, inserts like fourfingers into the second, third, fourth, and fifth ribs. Serratus posterior inferiororiginates at the spinous processes of the upper lumbar and lower thoracicvertebrae,passesobliquelyupandoutward,and,breakinglikeserratussuperior

intofourbranches, inserts intothefourlowerribs.Thesemusclesactupontheribs, serratus superior raising the ribs, and serratus inferior drawing the lowerribs down and widening the back. Along with quadratus lumborum (whichattachesfromthepelvistothelowestribandwhichwe’lldiscusswhenwegettothe thorax) and levatores costarum (which we’ve seen is one of the deepermusclesattachingtothetransverseprocessesofthevertebrae),serratusposteriorinferiorandsuperiorplayanimportantroleinfreeingtheribsandwideningtheback. When they are releasing, these muscles contribute to the freedom andfullness of the lower back, as well as the proper working of the diaphragm,whichisdirectlyrelatedtothelowerribs.

Figure1-25.Thirdlayer:serratusmuscles.

Levatorscapulae,rhomboidminor,andrhomboidmajoractuponthescapulae(Fig. 1-26). Originating at the transverse processes of the atlas and uppercervical vertebrae, levator scapulae attaches to the side of the scapula. Thismuscle,asitsnamesuggests,elevatesthescapula.Rhomboidminororiginatesatthe seventh cervical and first thoracic vertebrae and passes downward andoutwardtoinsertintothespineofthescapula.Rhomboidmajororiginatesatthespinousprocessesofthefourorfiveupperthoracicvertebraeandattachestothelowerspineofthescapula.Bothofthesemuscles,whicharesonamedbecauseoftheirrhomboidalshape,helptostabilizethescapulawhenthearmsarebeingmoved.Theselayersofbackmusclesarealsocrucialforbreathing;becausetheyrun obliquely and horizontally, their free action ensures the mobility andwideningoftheribs.

Figure1-26.Fourthlayer:scapulamuscles.

Themostsuperficialmusclelayerofthebackconsistsoftwopowerfulsheetsofmuscle coveringmost of the back: these are trapezius and latissimus dorsi(Fig.1-27).Trapeziusisadiamond-shapedmusclecoveringtheneckanduppershoulders. Itoriginatesbroadlyat theocciputand thespinousprocessesof thecervical and thoracic vertebrae and inserts into the upper scapula and theclavicle. Trapezius acts upon the shoulder blades, retracting them or pullingthemtogether,bracingtheshoulderinstrongskeletalmovements,andelevatingthe shoulder as in lifting weights. Latissimus dorsi is a broad, flat sheet ofmusclecovering the lowerhalfof thebackandinserting into thehumerus, the

upperarmbone.Itoriginatesatthespinousprocessesofthesacral,lumbar,andlower thoracic vertebrae, and from this very broad origin converges into theupperarmbone.Latissimusdepressestheupperarm,butbecauseitcontributestothewideningsupportoftheback,itprovidescrucialsupportandelasticitytotheactionoftheribsandunimpededbreathing.

Figure1-27.Fifthlayer:trapeziusandlatissimusdorsi.

TheLungsandTrachea

The trachea, orwindpipe, extends from the throat downward, anddivides intothetwobronchialtubesthatenterthelungs(Fig.1-28).Itisfourorfiveincheslong, and sits in front of the esophagus. It is composed of an elastic fibrousmembrane that is reinforced around two-thirds of its circumference bycartilaginous rings (the first of these is sometimes continuouswith the cricoidcartilageof the larynx).The trachea is linedwithmuscular fibers,aswellasamucous membrane that is continuous with the membrane lining the larynxabove.Atthelowerendofthetrachea,thetwobronchidivideintoprogressivelysmaller airways that subdivide to formbronchioles that lead into tinyballoon-like air sacs called alveoli, which is where the oxygen exchange takes placebetweenthelungsandtheblood.

Figure1-28.Thelungsandtrachea.

Thelungsthemselvesareconicalinshapewithconcavebasesthatconformtothedomesofthediaphragm.Therightlunghasthreelobesandtheleft,whichissmaller to accommodate the heart, only two. Each lung is of a lightweight,spongy texture andweighs a little over apound, and each is encasedwithin athinpleura,ormembrane,whichinturnisattachedtoapleurallayerliningtheinnerwallsof the thorax,pericardium,anddiaphragm.Theareabetweentheselayers,calledthepleuralcavity,containsathinfilmoffluidthatallowsthelungtoslideeasilyduringbreathing.

Theupperportionofthelungtapersupwardtoconformtothenarrowshapeof theribcage,andextends into theneckaboutan inchabove the levelof thefirstrib.Thebaseofthelungrestsuponthesurfaceofthediaphragm(seeFig.1-13).Thelungsoccupymostofthespacewithinthethoraciccavityexceptforthelarge area occupied by the pericardium. The lungs occupy not only the areabetweentheribsinfrontbutalsothedeepconcavityoneithersideofthespine.This space is formedby the rounded shape of the ribs,which extend outwardfrom the sidesof the spine andwhichalso curvebackward to the levelof thespinousprocessesofthevertebraebeforeroundingforwardtoformtheribcage.The area from the top of the lungs down to the level of the heart constitutesroughlyathirdofthetotalareaofthelung;at thelevelof theupperlung, thisareaisnearlyone-half.

LungCapacity

Themaximumamountofbreaththatcanbetakenintothelungsisaboutsixorsevenquartsorliters(thisisthe“totallungcapacity”);afteraforcedexhalation,abouttwoquartsremain(thisisthe“residualvolume”).Thedifferencebetweenthesetwoisthe“vitalcapacity”—aboutfourorfivequartsorliters(Fig.1-29a).

Figure1-29.a.Totallungcapacity.

Lungvolumewhentheribsanddiaphragmareinarelaxedstate(thatis,whenweareneitherinhalingnorforcingairoutofthelungs)isaboutthreequarts;thisis called the “functional residual capacity.” During normal resting breathing,onlyaboutapint,orhalfaliter,ofairisinhaledaboveandbeyondthefunctionalresidual capacity, and during shallow breathing even less; this is the “restingtidalvolume”(Fig.1-29b).During strenuous or forced exertion, the airflow isclosertotwoquarts—aboutthreepintsmorethanduringquietbreathing.Theairflowingintoandoutofthelungs—thatis,theairthatisactuallybeingbreathed—isthe“tidalflow,”asdistinctfromthethreequartsorsoofresidualairalwaysremaininginthelungs.

Figure1-29.b.Lungcapacityinrelaxedstate.

T

CHAPTER2

THELARYNX

helarynx,ororganofvoice,ishighlyspecializedandcomplex,butbeforeexaminingitsintricateanatomy,let’slookatitsbasicdesignandfunction.

Insimpleterms,thelarynxisavalvelocatedatthetopofthetrachea.Thisvalveis composed of two muscles, or folds of muscle, that can be pulled apart orbrought together.Whenwe breathe normally, the twomuscle folds are drawnapart, opening the valve so that air can pass through (Fig. 2-1a); when weswallow food or hold our breath, the muscle folds are tightened and drawntogether,closingthevalvesothatfoodandwatercannotentertheairway(Fig.2-1b).

Figure2-1.a.Vocalfoldsopen.b.Vocalfoldsclosed.c.Vocalfoldsapproximatedforphonation.

The valve also has a third function. When we want to produce sound, themusclefoldsaredrawntogether—notastightlyaswhenweswallow,butlooselyenoughthattheyarefreetovibrateasexhaledairpassesbetweenthem.Whenthis happens, they are set into motion by the airflow and begin to oscillate,generatingsoundwavesthatresonateinthespaceabovethelarynx,creatingthefullyformedsoundofthehumanvoice(Fig.2-1c).

The larynx, then, is basically a vibration mechanism. It contains theoscillatorsthatproducesound(thevocalfolds),anditcanbringthemtogetherso that theywill vibratewhenair (which is thepower source)passesbetweenthem, and draw them apart during normal breathing. It can also tense andstretch thevocal folds invariousways inorder toalter thevolume,pitch,andtypesofvibrationthatoccur.

BasicStructureoftheLarynx

Thelarynxismainlycomposedoffourcartilagesthatformthehousingforthevocalfolds.Atthetopofthetracheaisaring-likecartilagesimilartotheringsofthetrachea,calledthecricoidcartilage.Abovethatisthethyroidcartilage,whichismadeupoftwoplatesorwingsthatjoininthefront.Sittingonthebackpartofthecricoidcartilagewithinthewingsorwallsofthethyroidcartilagearetwopyramid-shapedcartilagescalledthearytenoidcartilages(Fig.2-2).

Figure2-2.Cartilagesandvocalcords.

Thevocalfolds—thevalvemuscles thatcometogetherandvibratewhenairhits themtocreatesound—aresuspendedbetweenthe twoarytenoidcartilagesandtheinnerfrontwallsofthethyroidcartilage.Whenthearytenoidcartilagesrotateinward,thisbringsthevocalfoldstogethersothattheyvibrateastheairpassingoutofthelungsforcesthemopen;whenthearytenoidcartilagesrotateback,thevocalfoldsareseparatedtoallowairtopassthroughfreelyagain(Fig.2-2).

TheFrameworkoftheLarynx

Thehyoidbone,thethyroid,cricoid,andarytenoidcartilages,theepiglottis,andthe tiny corniculate and cuneiform cartilages form the complete framework ofthe larynx (Fig. 2-3). The thyroid cartilage is the most prominent part of thelarynx(Fig.2-4).Where the twoplatesof the thyroid join in front, theyanglesharplyforwardinmen,formingtheprominentbumpcalledtheAdam’sapple.The sides of the plates, or lamina, are rather smooth except toward the back,wherearidge,beginningata tubercleorprotrusion,runsdownandforwardtothelowerborderofthelamina,formingtheobliqueline.Atthebackpartofeachlaminathereisalongupwardprojectioncalledthesuperiorcornu.JustabovethethyroidcartilageistheU-shapedhyoidbone.Thisbone,whichformstherootofthe tongue, is an important part of the framework of the larynx because thelarynxissuspendedfromthehyoidbonebyaligamentattachingtothesuperiorcomu,aswellasbythethyrohyoidmembrane.Adownwardprojectionfromthebackpartofthelamina,calledtheinferiorcornu,formsapivotwiththesidesofthecricoidcartilage(Fig.2-4).

Figure2-3.Theframeworkofthelarynx.

Figure2-4.Thyroid,cricoid,andarytenoidcartilages.

Thecricoid,orring,cartilagewasgiventhisnamebecauseofitsresemblancetoasignet ring—aringwitha large flat surface for imprintingone’sseal.Thefront of the cricoid is narrow, not much thicker than the rings of the tracheabelowit;thebackisthickerbecauseitservesasattachmentforthemusclesthatabduct,oropen,thevocalfolds,andasasurfaceareaforthearytenoidcartilages(Fig.2-4).

Thearytenoidcartilages,whenplacedtogether,resembleapitcher;hencetheirname(fromtheGreekwordforpitcher).Becauseoftheirshape,thearytenoidsare also sometimes called the “pyramid cartilages.” At its base, the arytenoidformsajointwhereitsitsonthecricoidcartilage;therearealsotwoprotrusions

or angles, the muscular process and the vocal process. The muscular processprojects outward andbackward and serves as attachment for the posterior andlateralcricoarytenoidmuscles;thevocalprocessprojectsanteriorlyandservesasattachmentforthevocalfolds(Fig.2-4).

TheEpiglottis

The epiglottis is a broad, leaf-shaped cartilage situated at the front part of thelarynx(Figs.2-3and2-9).Itstandsuprightandflapsdownduringswallowingtohelptodirectfoodtowardtheesophagus.Itisattachedatitsbasetothethyroidcartilage.Itssidesanglebackwardanddowntothearytenoidcartilagestoformakindofcollararoundtheopeningofthelarynxcalledthearyepiglotticfolds.Thetopofthearytenoidcartilageisnotpointedbutflat;thecorniculatecartilages(orcartilagesofSantorini)aresmallconicalstructuresthatextendthesummitofthearytenoidsandserveasattachmentforthearyepiglotticfolds(seeFigs.2-4and2-9). (The aryepiglottic folds themselves are stiffened by the cuneiformcartilages, also called the cartilages of Wrisberg, which are small, elongatedcartilages embedded in the aryepiglottic folds.) This collar helps to keep foodout of the larynx; with the wing of the thyroid cartilage on the other side, itformsachannel,calledthepiriformsinus,whichallowsliquidstopassaroundthelarynxandintotheesophagus(seeFig.6-5).

This completes the basic framework of the larynx. The thyroid and cricoidcartilages and the base of the arytenoids are composed of a tough hyalinecartilagethat tendstoossifywithage; incontrast, theapicesof thearytenoids,theepiglottis,thecorniculate,andthecuneiformcartilagesremainelastic.

CricoarytenoidJoint

The cricoarytenoid joint, which is formed by the articulation of the arytenoidcartilages with the cricoid cartilage, is the key joint that makes it possible toopenandclose thevocal folds.On thebackof thecricoidcartilage is a smallnotch;toeithersideofthisnotch,slopingdownsharplyandanglingapartat90degreestooneanother,aretwoelliptical,convexfacetsforarticulationwiththearytenoidcartilages (Fig.2-5a).Thebaseof the arytenoid cartilage is concaveand sits nicely on these convex facets, forming a synovial joint that issurrounded by a joint capsule and reinforced by the posterior cricoarytenoid

ligament(Fig.2-5b).

Figure2-5.Cricoarytenoidjoint:a.Articularfacetsoncricoid;b.Movementofarytenoidcartilagesonthecricoidcartilage.

The posterior cricoarytenoid ligament arises from the cricoid cartilage and,fanning upward and obliquely forward, attaches to the medial surface of thearytenoidcartilagemidwaybetweenthevocalprocessandthemuscularprocess(notpictured).

Thearytenoidcartilagesmoveon thecricoidcartilages in twoways: inwardandoutwardrocking,andmedialandlateralsliding.Thevocalprocessescometogether when the arytenoid cartilages rock downward and inward, and apartwhentheyrockupwardandoutward.Whenthecartilagesslidetowardtheback,thisbringstheapicestogetherbutnotthevocalprocesses(Fig.2-5b).

CricothyroidJoint

Theothermainjointofthelarynxisthecricothyroid,whichmakesitpossibletomovethethyroidcartilageinrelationtothecricoidcartilage.Wesawamoment

ago that the inferior cornua pivot on the cricoid cartilage.On the sides of thecricoidcartilage toward theback is a small raised facet; this articulateswithasmall facet on the inner surfaceof the inferior cornu (Fig.2-6). This synovialjoint is bounded by three ligaments. The posterior ceratocricoid ligamentattaches toward the upper sides of the cricoid plate and runs downward andoutward toattach to the inferiorcornuof the thyroid.The lateralceratocricoidligament connects the inferior cornu with the side of the cricoid cartilage.Finally,theentirearticulationisenclosedwithinacapsularligamentlinedwithasynovialmembranethatlubricatesthejoint(seeinset,Fig.2-3).

Figure2-6.Cricothyroidjoint.

Twomovements takeplaceat this joint:arockingorpivotingof the thyroidcartilage in relation to thecricoid;and the thyroidcanglide forwardoutof itsarticulationtomoveforwardinrelationtothecricoidcartilage.Theseactions,aswe’ll see later, stretch the vocal folds during vocalization and raise the pitch(Fig.2-6;seealsoFig.2-18).

ConusElasticus

Sometimes called the cricothyroidmembrane, the conus elasticus is an elasticmembrane connecting the upper border of the cricoid cartilagewith the vocal

foldsandthefrontofthethyroid(Fig.2-7).Itiscone-shaped(henceitsname),andattachesfromtheentirecircumferenceofthecricoidcartilageandconvergesupwardtojointhefrontandbackpartsofthethyroidandtheinnermarginsofthevocalfolds—akindoftent-likestructurewhosebaseisthecricoidcartilageandwhoseapexis thefrontof the thyroid.Thepartof theconuselasticus thatconnectstheupperborderofthefrontofthecricoidwiththelowerborderofthefront of the thyroid is sometimes called the cricothyroid ligament, or middleportionofthecricothyroidmembrane.Thiscentralportionoftheconuselasticusisthickerthanthelateralportions.Thelateralportionsextendfromthesuperiorborder of the cricoid cartilage to the margin of the vocal folds, forming amembrane from the top of the trachea to the vocal folds. This membraneprovides a kind of lining for the vocal folds and so is continuous with theligamentousbandsorvocalligaments.

Figure2-7.Conuselasticus.

TheInterioroftheLarynx

Thecavityofthelarynxextendsfromthesuperiorapertureofthelarynxtothecricoidcartilage(Fig.2-8).Viewedincoronalsection,theepiglottisisthelargeflapoftissuegivingaccesstothelarynx.Thepartofthecavitylyingabovethevocal folds is called the vestibule. The superior aperture of the larynx, oropening to the larynx from above, is bounded by the epiglottis in front, thearytenoidsinback,andthearyepiglotticfoldsalongthesides.

Figure2-8.Theinteriorofthelarynx.

Thevocalfolds—sometimesreferredtoasthevocalcords—areactuallypartofalargercomplexofmuscleswithtwobelliesorfolds,anupperandalowerpair,sometimescalled thesuperiorandinferior thyroarytenoids(Fig.2-8).Thesuperiorthyroarytenoidsattachtothefrontofthethyroidcartilagejustbelowthebase of the epiglottis, and behind to the anterior surface of the arytenoidcartilages.Theydonotextendinwardasfarasthelowerfolds,arenotactuallyinvolvedinphonation,andarethereforesometimescalledthefalsecords; theyaremorecommonlyknownas theventricularbands.Theirmain function is toassistthetruecordsinclosingthevalvetightly.Becausetheyangledownward,theyaredesignedtoresiststrongairpressurefrombelowandarethereforewellsuitedtoclosinguptheairway(seeFig.6-6).

The lowerpair,or inferior thyroarytenoids, are the truevocalcordsor foldsand have come to be known as the vocalismuscle. The innermargin of eachfold, aswewill see in amoment, forms thevocal ligament. In contrast to thepinkmembraneofthevocalfoldsthemselves,theligamentsarewhiteincolor.Theseligamentsaresometimesreferredtoasthevocalbands,incontrasttothevocal lipsof the folds themselves.Thevocalismusclesareverywell suited toreceivetheflowofairfromthelungsandtovibrateefficiently.

Because the vocalis muscle, when viewed from above, lies closer to themidlinethanthesuperiorthyroarytenoid,itissometimescalled“thyroarytenoidinternus” and the superior thyroarytenoid (which lies to the outside)“thyroarytenoid externus.” The generally accepted terminology now is simplyvocalisfortheinferior,truevocalfoldsandthyroarytenoidfortheupperfolds.

Betweenthethyroarytenoidandvocalismusclesistheventricleofthelarynx,which isanoblongcavity (Fig.2-8).This sinus alsohas small air sacs that insomespeciesfillwithair.Theventricleofthelarynxextendsupwardtoformasmall pouch or cavity between the superior or false vocal cord and the innersurfaceofthethyroidcartilage,calledthesacculuslaryngis,orlaryngealpouch.Thissaccontainsmucus-producingglandsandissurroundedbythearyepiglotticmuscles

MusclesoftheEpiglottis

The aryepiglottic muscle arises from the apex and anterior surface of thearytenoid cartilage and passes obliquely upward to join the aryepiglottic foldsalongthesidesoftheepiglottis(Fig.2-9).Thismuscleissometimesdescribedintwo parts, a superior arytenoepiglottideus muscle arising from the apex andanterior surface of the arytenoid cartilage and blending into the aryepiglotticfolds, and an inferior arytenoepiglottideus muscle arising from the anteriorsurface of the arytenoid cartilage and blending into the anterior surface of theepiglottis.Thesuperiorportionofthismuscleconstrictsthesuperiorapertureofthe larynx to prevent food from entering the airway during swallowing. Theinferiorportionofthismuscle,sometimescalledthecompressorsacculilaryngis,compressesthesacculus;bysqueezingthemucousglands,thesemuscleshelptolubricatethevocalfolds.

Figure2-9.Thearyepiglotticmuscleoftheepiglottis.

The thyroepiglottic (or thyroepiglottideus) muscle arises from the innersurfaceofthethyroidcartilagejustoutsidethethyroarytenoidmuscle.Itsfibersformtheouterwallof thesacculus laryngisandalsojoin into thearyepiglotticfolds(Fig.2-10).Thismuscleisadepressoroftheepiglottisbutalsoassiststhearyepiglotticmusclesincompressingthesacculuslaryngis.

Figure2-10.Thethyroepliglotticmuscleoftheepiglottis.

TheStructureoftheVocalFolds

Thevocal foldsareanexceedinglycomplexmusclewhosestructure isnotyetfullyunderstood.Itisgenerallyagreedthatitsmainfibersarelongitudinal,andrunthelengthofthevisiblemuscle.Inthe1950s,someresearchersclaimedthatnoneof its fibers ran the lengthof themuscle and that someoriginated at thearytenoidsandattachedintothevocalligament(aryvocalismuscle)whileothersoriginated at the thyroid and attached into the vocal ligament (thyrovocalismuscle),creatingakindofdiagonalpattern.Whenthemusclescontracted,they

wouldactuallypluckthevocalligament,sothatthevibratoryactionofthevocalfolds was not aerodynamic andmyoelastic but actuated by nervous impulses.This view (called the “neurotaxic” or “neurochronaxic” theory) has beenrejected, but the terminology corresponding to the two muscles sometimespersists (aryvocalis and thyrovocalis).Also, it is known that the folds containsomemusclefibersthatrunacrossthemaindirectionofthelongitudinalfibers;thesemayplayaroleinsqueezingorthinningthevocalfolds.Inanycase,thevocalfoldshaveverydelicatefibersandareabletocontractinsubtleways,sothatthesefibersplayaroleinfinelytuningthethicknessofthevocalfoldsandcontrollingtheirvibrations.

Viewed under a microscope, the vocal folds consist of five layers: theepithelium;thesuperficial,intermediate,anddeeplayersoflaminapropria;andthebodyof thevocalismuscle itself.The epithelium forms theoutermucosallayerandhelps tokeep thevocal folds lubricated; thenextfour layersbecomeprogressivelyfirmerandprovidebothstiffnessandelasticitytothevocalfolds.

These five layers can be divided functionally into three groups. Theepitheliumandfirstlayeroflaminapropriaformaloosemucosalstructurethatiswell suited to vibratingwhen air flows through the glottis. The two deeperlayers of lamina propria are composed ofmore tightlywoven collagen fibers,whichformthevocalligament.Themucosallayervibratesfreelyoverthevocalligament in singing. Underneath the mucosal layer and vocal ligament is themuscleitself,whichisquitefirmandcanbecomeevenfirmerwhenitcontracts.

IntrinsicMusclesoftheLarynx

Therearefiveintrinsicmusclesofthelarynx.Thefirstofthese,thecricothyroid,moves the thyroid cartilage in relation to the cricoid. Because it lies on theoutside of the thyroid and is supplied by the same nerves that supply theextrinsic muscles of the larynx, it is arguably an extrinsic, not an intrinsic,muscleofthelarynx.Thecricothyroidisatwo-partmuscle.Thefirstpart,calledthe oblique part or pars obliqua, arises from the side of the cricoid toward itsfront and, passing upward and backward, inserts into the inferior cornu andlowerborderof the laminaof the thyroidcartilage.Thesecondpart,calledthevertical part or pars recta, inserts in the cricoid cartilage just in front of theobliquepartand,passingmoreverticallyupward,insertsintothelowerborderofthelaminaofthethyroid(Fig.2-11).

Figure2-11.Cricothyroidmuscle.

TheIntrinsicMusclesoftheLarynxFivesetsofmusclescontrolthemovementandactionofthevocalfolds,depictedinthisdrawingascoloredbungeecords:a.theposteriorcricoarytenoidmusclesopenorabducttheglottis(redbungeecords);b.thetransversearytenoidmusclesclosetoadducttheglottis(bluebungeecord);c.thelateralcricoarytenoidmusclescloseandpartiallyadducttheglottis(purplebungeecords);d.thecricothyroidmuscleslengthenthevocalfolds(yellowandorangebungeecords);e.thethyroarytenoidmusclesshortenortensethevocalfold(greenbungeecords)

Posteriorcricoarytenoidmuscle

Thyroarytenoidmuscles

Cricothyroidmuscles

Transversearytenoidmuscles

Lateralcricoarytenoidmuscle

Thevocalismuscleoriginatesattheinnerfrontsurfaceofthethyroidcartilageto either side of the thyroid angle, and inserts into the vocal process of thearytenoidcartilage(Fig.2-12).The innermostmarginof thevocalismuscle,aswe have seen, is made up of a ligament that is continuous with the conuselasticus. The ligament attaches to the tip of the vocal process; the vocalismuscleitselfattachestothetipjustbesidethevocalligamentandlaterallytotheanteriorsurfaceofthevocalprocess(seeFigs.2-7and2-8).

Figure2-12.Vocalisandthyroarytenoidmuscles,asviewedfromabove.

Thethyroarytenoidmuscleoriginatesat theangleof the thyroidcartilageonitsupperborderand,pointingslightlyoutward,insertsbroadlyintothearytenoidcartilagefromthevocalprocesstothemuscularprocess.Itisplacedlaterallytothefibersofthevocalismuscle(Fig.2-12).

Theglottisisthechinkoraperturebetweenthevocalfolds.Inmenitaverages23mminlength,orjustunderaninch;inwomen,itaverages19mminlength,oraboutthree-quartersofaninch.Aboutthree-fifthsofthislength,calledthevocalportion, is the muscular part of the vocal fold; two-fifths is made up of thearytenoid cartilages and is called the respiratory portion. The glottis ischangeable in shape, depending on whether the vocal folds are abducted or

adducted;evenwhenthefoldsthemselvesarecloselyapproximated,astheyareduringphonation, there can still be a chinkbetween the arytenoids.The acuteangleoftheglottiswherethevocalfoldsattachtothethyroidcartilageiscalledtheanteriorcommissure(Fig.2-13).

Figure2-13.Theglottis.

The posterior cricoarytenoid is the largest intrinsicmuscle of the larynx.Aprominent vertical ridge runs along the back plate of the cricoid; the musclearises from the depressions on either side of this central ridge. Its fibers pass

upward and outward to insert into the muscular process of the arytenoidcartilage, the upper fibers running nearly horizontally and the lower fiberspassingalmostverticallyupwardinordertoconvergeintothesamepointonthearytenoid(Fig.2-14).

Figure2-14.Theposteriorcricoarytenoidmuscle.

The lateral cricoarytenoid is situated at the sides of the cricoid cartilage. Itarisesfromtheexternalsurfaceofthesideofthecricoidcartilageanditsupperborder. Its fibers pass obliquely upward and backward and insert into the

muscularprocessofthearytenoidcartilage(Fig.2-15).

Figure2-15.Thelateralcricoarytenoidmuscle.

The transverseandobliquearytenoidmusclesaresituatedat thebackof thearytenoids and occupy the depressions at the back of each arytenoid. Thetransversearytenoidarisesfromtheouterborderoftheposteriorsurfaceofonearytenoidandattachestotheother.Theobliquefiberspassfromthebaseofonearytenoidtotheapexoftheother(Fig.2-16).

Figure2-16.Thetransverseandobliquearytenoidmuscles.

ActionsoftheIntrinsicMusclesoftheLarynx

The actions of the intrinsic muscles of the larynx can be divided into fourcategories:

•thosethatopentheglottisbyabductingthevocalfolds(Figs.2-17);

Figure2-17.Actionoftheposteriorcricoarytenoidmuscles,theopeners.

•thosethatclosetheglottisbyadductingthevocalfolds(Figs.2-18,and2-19);

Figure2-18.Actionofthelateralcricoarytenoidmuscles,whichclosetheglottis.

Figure2-19.Actionofthetransverseandobliquearytenoidmuscles,whichclosetheglottis.

•thosethatlengthenthevocalfolds(Fig.2-20);

Figure2-20.Thecricothyroid,astretchingmuscle.

•thosethatshortenandrelaxthevocalfolds—thetensors(Fig.2-21).

Figure2-21.Stretchingofthevocalfolds.

Thestretchingofthevocalfoldsisperformedbythecricothyroidmuscle(Fig.2-20),whichattachestothecricoidcartilageandthethyroidcartilageandpullsthe two cartilages together in such a way that the distance between the twoextremities of the vocal folds is increased, causing them to stretch. We sawabove that the cricothyroidmuscle has twoparts: the vertical part (pars recta)andtheobliquepart(parsobliqua).Theobliquepartofthecricothyroidpullsthethyroidcartilageforwardinrelationtothecricoid(thisiscalledtranslation);thevertical part pulls the thyroid cartilage down so that it pivots or rotates at thecricothyroidjoint(Fig.2-21).Actingtogether,thethyroidcartilageisrotatedandpulled forward, which stretches the vocal folds by increasing the distancebetween their attachments at each end. If the thyroid cartilage is fixed by theextrinsic muscles, the cricoid cartilage will move in relation to the thyroidcartilage, rather than the otherway around. In either case, however, the vocalfoldsarestretched.

Thetensorsarethethyroarytenoidandvocalismuscles(Fig.2-22),which,bycontracting,drawthearytenoidcartilages toward the thyroidcartilageandthusshorten(or relax) thevocal folds.Theactionof thevocalisand thyroarytenoidmuscles thus regulates theelasticityand tensionof thevocal folds,whichalsomaintainsclosureoftheglottis.

Figure2-22.Tensorsofthelarynx.

Acting together, the thyroarytenoid, the transverse arytenoid, and thearyepiglotticmusclestightlyclosetheglottis;thisoccursduringswallowingandwhenwecoughorholdourbreath.

CricothyroidandThyroarytenoidAntagonism

We saw earlier that the main stretcher of the vocal folds is the cricothyroid,which, by moving the thyroid and cricoid cartilage in relation to each other,draws the two opposite ends of the vocal folds apart, increasing their length.Opposed to this action are the vocalis and thyroarytenoidmuscles,which pullthe two poles together. In normal speaking or chest voice, the vocalismusclemustbeactiveandrequirestheopposingstretchingactionofthecricothyroidtoproperlybringitintoplay.

CricothyroidandPosteriorCricothyroidAntagonism

Inorderforthevocalismuscletobestretched,thearytenoidsmustbeanchoredin place; otherwise, the force exerted by the tensors (vocalis) and stretchers(cricothyroid)wouldsimplypullthearytenoidcartilagestowardthefrontofthethyroid.Thisanchoringisaccomplishedbytheposteriorcricoarytenoids,whichfixthearytenoidsfrombehind.

ClosureoftheGlottisandMedialCompression

When the two ends of the vocal folds are drawn apart by the cricothyroidmuscle, thevocal folds are stretched andbecome thinner.This causes them togap in themiddle so that they are imperfectly approximated even though thetransverse arytenoids have approximated the arytenoid cartilages. The lateralcricoarytenoidsarecrucialinbringingaboutfullclosureoftheglottis,exertingmedial compression and in this way bringing the vocal cords together. Thevocalismusclemustalsobeactive,sincenoactionofthearytenoidscantotallyensurefullapproximationifthevocalfoldsthemselvesareentirelylax.Tensioninthevocalismusclespullsthevocalfoldstogether,whichinturnrequirestheantagonisticactionoftheposteriorcricoarytenoidstoanchorthearytenoids.Sothetransversearytenoidsareactiveinapproximatingthevocalfolds;thelateralcricoarytenoids are active in increasing medial compression of the folds; thecricothyroidsareactiveinstretchingthevocalfoldsandopposingthepullofthevocalismuscle;thevocalismuscleisactiveintensingthefoldsthemselves;andthe posterior cricoarytenoids anchor the arytenoid cartilages in place—a veryactiveandsynergisticcoordinationofmuscles.

ActionoftheLarynxMusclesinChestRegister

In chest voice, the transverse arytenoids are active in approximating the vocalfolds,butonlyworkinglightly.Thecricothyroidsareactiveinregulatingpitch,with increasingactivitycorresponding tohigherpitch.Thevocalismuscleactsantagonistically to the cricothyroid; by resisting the stretching effect of thecricothyroid, thevocalis remains thick,vibratingata largeamplitudeandoverits full surface with a wave-likemotion that begins at the bottom andmovesupward,creatingtherichharmonicsofthechestvoice(Figs.2-23and2-24).Theactivityof thevocalisalsocontributes to raising thepitchand to increasing itsintensity. In order to anchor the arytenoids against these pulls, the posteriorcricoarytenoidisactive.Thelateralcricoarytenoidsarelightlyactiveinbringing

aboutmedialcompressionofthevocalfolds.Sincethefoldstendtogapundertension,andsincetheapproximationofthetransversearytenoidsdoesnotbringthe vocal processes together, the lateral cricoarytenoids are crucial in bringingaboutfullclosureoftheglottis.

Figure2-23.Waveactionofthevocalfolds.

Figure2-24.Vocalfoldsinchestvoice:thevocalfoldsarerelaxedandvibrateloosely,producingtherichchestvoice.Inset:theentirebodyofeachvocalfoldisincontactwiththeotheroneasitvibrates.

ActionoftheLarynxMusclesinFalsettoRegister

In falsetto register, the vocal folds are approximated by the transversearytenoids.Thecricothyroidisactiveonlyinthelowerpartofthefalsettorange;at a certain point thevocal folds aremaximally stretched and the cricothyroidactivitysimplyremainsatitsmaximum.Thevocalismusclesarequiterelaxed,allowing thecricothyroid,which isnotbeingopposedby the tensingactionofthevocalismuscle, to actively stretch thevocal folds (Fig.2-25).Because thefolds are stretched, they also become thinned and their amplitude increases;sincethevocalfoldsarenolongervibratingwithawave-likemotionandonlythe vocal bands are moving, this creates a thin falsetto sound. The vocalismuscledoescontractsomewhattoregulatethepitch,butmuchlessthaninchest

voice.Against thispull, theposteriorcricoarytenoidsmustbesomewhatactiveinordertoanchorthearytenoidcartilages.Becausethevocalfoldsarestretchedandthinned,theytendtogapagreatdealinfalsetto,preventingtheglottisfromclosing entirely. In order to resist this gapping tendency, the lateralcricoarytenoidsmustactivelyworktomaintainmedialcompressionofthevocalfolds. Also, because the vocal folds do not increase in length in the upperoctavesofthefalsetto,pitchisdeterminedbylongitudinaltensiononthevocalligaments,aidedbytheextrinsicmusculatureaswellasbreathpressure.

Figure2-25.Vocalfoldsinfalsetto:thevocalfoldsaretautandvibratemorequickly,producingthemoreflutelikefalsettosound.Inset:onlytheinnermarginofeachvocalfoldisincontactasitvibrates.

ActionoftheLarynxMusclesinHeadRegister

Several elements of chest voice combinewith falsetto register to produce thehead voice. In order to produce the higher pitches of the head voice, thecricothyroid muscle must work actively to maintain full stretch on the vocalfolds.Tomaintain thefull toneof theheadvoice,however, thevocalismusclecontractsandcontinuestoactivelyvibrate,asitdoesinchestvoice.Becausethevocalfoldsareactive,theygaplessthaninfalsettoandairisthereforeutilizedmore efficiently, requiring less breath to produce the tone. Also, when thevocalis muscles are active, there is more glottal resistance and moreaerodynamicefficiency.Thetransversearytenoidsmustalsobeactiveinordertomaintain approximation of the vocal folds and intensity of tone as well asefficiency of breath. Activity of the lateral cricothyroids is also high; thismaintainsmedialcompressionoftheglottiswhilethefoldsareundermaximumlengtheningandtension.Becausethearytenoidsmustbeanchoredagainstthesestrongpulls, theposterior cricoarytenoidsarealsohighlyactive inheadvoice.Aswithfalsetto,thevocalfoldsaremaximallystretched,sothatriseinpitchisassociatedwithanincreaseinlongitudinaltensionofthevocalbands.This,andthe need to maintain full stretch on vocal ligaments with an active vocalismuscle,requiresveryactiveworkingoftheextrinsicmusculature.

W

CHAPTER3

THEEXTRINSICMUSCLESOFTHELARYNX

e’ve seen that the larynx and its intrinsic muscles precisely adjust thevocal folds so that they vibrate efficiently, creating subtle nuances in

timbre, focus, and pitch. As a sound-producing mechanism, the larynx is theprincipalorganofvoice.But the larynx isalsosuspendedwithinanetworkofthroat muscles that act on it from without and therefore form its extrinsicmusculature.

The extrinsicmuscles of the larynx serve two functions.First, theyassist inswallowing.Wesawinthelastchapterthattheprimaryfunctionofthelarynxistocloseuptheairwayinordertopreventfoodfromentering.Tofurtherprotectthe airway, extrinsic muscles attaching to the hyoid bone and larynx pull thelarynxupandforward.Thistakesthelarynxoutofthepathofthefoodandhelpsto close up the collar of the larynx, ensuring that the food passes into theesophagusandnotthetrachea(seesidebar).

The extrinsic muscles also play a crucial role in vocalization. To functionefficiently as a sound-producing organ, the larynxmust not be hindered in itsactionbymusculartension,andthethroat,astheresonatingchamber,mustbeopen.Whenwesing,however,theswallowingmusclesthatelevateandconstrictthelarynxtendtocomeintoplay,particularlywhenwesinginfalsettoorheadregisters.Inordertomaintainalowpositionofthelarynxandanopenthroat,theactionof theswallowingmuscles thatelevate the larynxmustbecounteredbymusclespullingdownon the larynx,antagonistically supporting itwithinawebofmuscles.Thismakesitpossibletoraisethepitchwithoutinterferingwiththevibratoryactionofthelarynx,andtomaintainanopenthroat.Engagingthesuspensory muscles in this way is one of the most important skills a trainedsingermustlearn.

TheSuspensoryMusclesoftheLarynx

Four muscles directly form the suspension of the larynx during the act of

singing.Wesawearlierthatthehyoidboneislocateddirectlyabovethethyroidcartilage,whichissuspendedfromthehyoidbonebythethyrohyoidligament.Corresponding to the thyrohyoid ligament is the thyrohyoid muscle, whichconnects the thyroidcartilagedirectlyabove to thehyoidbone, supporting thelarynxfromabove.Thethyrohyoidmuscleisacontinuationofthesternothyroidmuscle,originatesattheobliquelineofthethyroidcartilagejustinfrontofthesternothyroid,andrunsverticallyupward to insert into thebodyandcornuaofthehyoidbone(Fig.3-1).

Figure3-1.Suspensorymusclesofthelarynx.

Anothercrucialelevatorofthelarynxisthestylopharyngeusmuscle.Onthetemporalboneson thebaseof theskullare twosmallspikescalled thestyloidprocesses (Fig. 3-2). Stylopharyngeus arises from the base of the styloidprocesses and, angling forward, attaches to the posterior border of the thyroidcartilageand toeither sideof thewallsof thepharynx,whichwe’ll lookat inChapterFour.Stylopharyngeusdirectlyconnectsthethyroidcartilageaswellasthesidesofthepharynxwiththestyloidprocess,pullingupwardonthelarynxandthroat(Fig.3-1).

Figure3-2.Baseofskullwithstyloidandmastoidprocesses.

T

Countering the upward force of these muscles is the sternothyroid, whichoriginatesattheinnerborderofthesternumandthefirstribandinsertsintotheobliqueridgeonthewingofthethyroidcartilage(Fig.3-1).

Cricopharyngeusisanothercrucialsuspensorymuscle,anchoringthethyroidcartilageofthelarynxdirectlybacktothepharynxandesophagus.Thismuscleoriginatesatthecricoidcartilageandiscontinuouswiththeinferiorconstrictorofthepharynx(Fig.3-1).

Basedonthedirectionsindicated,wecaninferwhatactionsareperformedbythesemuscles.Thethyrohyoidandstylopharyngeus,aswellaspalatopharyngeus(whichwe’lltalkaboutlaterwhenwelookatthepalate),pullthelarynxupandback;theyarethereforeelevatorsofthelarynx.Thesternothyroidmusclepullsthe larynxdownand is therefore adepressor; cricopharyngeusanchors it backanddownandisthereforeanotherdepressor.Sothelarynxissuspendedfromthehyoid bone and connected back and up to the skull via stylopharyngeus; it isconnectedbelowtothesternumviasternothyroid;anditisconnectedbehindtothe esophagus via cricopharyngeus—a complexweb ofmuscular support thatextendsup,back,andtothesternumbelowandtothethroatdirectlybehind,sothatitisliterallysupportedwithinamuscularscaffolding,sometimescalledthe“suspensory muscles” of the larynx, which antagonistically support it fromvariousdirections(Fig.3-1).

wo other muscles contribute indirectly to the suspensory support of thelarynx during vocalization. Sternohyoid directly connects the hyoid bone

with the sternum; it originates at the clavicle and sternumon its insideborderandpassesupwardtoinsertintothelowerborderofthebodyofthehyoidbone(Fig.3-3).Itassiststhesternothyroidinactivelypullingdownonthelarynxandcounteringtheupwardpulloftheelevators.

Figure3-3.Completesuspensorymusclesofthelarynx.

Omohyoidarises fromtheupperborderof thescapulaand,passingupward,changesangletopassalmostverticallyupwardtoinsertintothelowerborderofthebodyof thehyoidbone (Fig.3-3).Where themuscle formsanangle, it isactually tendinous; this section is held in place by a sheath formed by thecervical fascia. Like sternohyoid and sternothyroid, it depresses or lowers thelarynx.

ActionoftheSuspensoryMusclesduringSinging

Thestabilizingactionofthesuspensorymusclesaidsintheproductionofhightones in specificways.Aswe saw in the lastchapter, the cricothyroidmuscleraises the pitch by stretching the vocal folds. Activity of the cricothyroids,however,isassociatedwiththeconstrictingactionofthethroatmuscles,sothatuntrained singers tend to tighten the larynx as they ascend inpitch.They alsotend toraise the larynxbecause,as thepitch increases, thecricothyroidsareattheir maximal activity, and stretching of the vocal bands has to be aided byelevators of the larynx (such as thyrohyoid, stylohyoid, geniohyoid, and

hyoglossus),whichpullupwardonthethyroidandtipitforward,stretchingthecords(Fig.3-4a).Allofthisactivityisassociatedwithtighteningthethroat,ascanclearlybeseen inuntrainedsingerswho“reach” forhighnotesbyraisingthe larynx and tightening theentireneckand larynx in theprocess (Figs. 3-4bandc).

Figure3-4.a.Elevationofthelarynxinsinging;b.Strainedappearanceofsinger;c.Linesofforceoftheelevators.

rainedsingers,incontrast,areabletoraisethepitchwithoutelevatingthelarynx

Tor tightening the throat. This is partly because they are more familiar andcomfortablewith the falsetto register,and thereforedonot force thechestvoice activity into the falsetto range. They are also able to engage the

extrinsicmusclesthatdepressthelarynxinordertoactivelycountertheupwardpull of the extrinsic muscles that elevate the larynx—in particular, thesternothyroid and sternohyoidmuscles (Fig. 3-5). Pulling down on the larynxandmaintainingitinalowerpositionhastwobeneficialeffects.First,itpullsthethyroidcartilageforwardandinthiswayassiststhecricothyroidinlengtheningthe vocal folds. Second, lowering the larynx maintains a more open andelongatedthroat.

Figure3-5.Actionofthesuspensorymusclesduringsinging.Insetshowslinesofforceofthemuscles.

Thedownwardpullof the sternohyoidandsternothyroidmuscles isassistedby the trachea,which exerts a “tracheal pull” on the cricoid cartilage, and theesophagus,whichtendstopulldownwardonthearytenoidcartilages.Thispullsthe cricoid cartilage backward and anchors it, stretching the vocal folds toproduceahightonewhilemaintainingalowpositionofthelarynx.

Another elevator that actively participates in the antagonistic activity of theextrinsicmusclesisthestylopharyngeusmuscle.Bypullinguponthehornsofthe thyroid cartilage, this muscle tilts the thyroid forward, assisting in thestretchingactiononthevocalfolds(asinFig.3-5).Andsincetheoriginsofthemuscleatthestyloidprocessesarefartherapartthanitsinsertionsinthethroat,thestylopharyngeuspullsthepharynxupandoutward,helpingtodilateoropenthe throat.Because the sternothyroid is antagonisticallyopposing theactionofthe elevators, the stylopharyngeus muscle can produce these effects withoutactuallyraisingthelarynx.

Activating the suspensory muscles that support the larynx in a balanced,antagonisticactionhasamarkedeffecton timbre, resonance, andvocal range.Theabilityofthelarynxtofunctionoptimally,aswellastheabilitytosingwithan “open throat,” depend to a large extent upon the antagonistic action of thesuspensorymusclesofthelarynx.

SupportedFalsetto

The extrinsic muscles are particularly important in producing the supportedfalsetto (Fig.3-6).Duringnormal falsettovoice, thevocalismuscle is relaxed,whilethemusclesthatraisethepitch,thecricothyroidmuscles,activelythinthevocalcords,counteredbytheposteriorcricoarytenoidmuscle.Inthesupportedfalsetto,thesuspensorymusclesmoreactivelysupportthelarynx.Inparticular,thesternothyroidmuscleactivelycontributestothestretchingprocess,aswellasthe thyrohyoid, to help the closers oppose the action of the cricothyroid. Thishelps to reinforce the blend between registers because, instead of a breakbetween registers, theantagonism ismaintained throughout—a truly supportedvoice.Engagingthesuspensorymusclesinthiswaymakesitpossibletomanagetheregisterbreakskillfullyandisabasicpartofthesinger’straining.

Figure3-6.Actionofsuspensorymusclesinsupportedfalsetto.Insetshowslinesofforceofthemuscles.

HeadVoice

In“head”voice,thesuspensorymusclesofthelarynxareattheirhighestactivity(Fig.3-7). In head voice the vocalis remains active and therefore opposes thecricothyroid.Thecricothyroidisatitsmaximumactivityandcannotlengthenthevocalfoldsbeyondacertainpoint;itisactivelyassistedbythestylopharyngeusandpalatopharyngeus(seeFig.4-6)muscles,whichpulluponthethyroidand,in conjunction with the sternothyroid, tilt the thyroid cartilage forward anddown.Theseupwardpullsarecounteredbythesternothyroid,sternohyoid,andomohyoidmuscles,whichopposetheupwardpullof theelevators.Finally, thecricopharyngeusmuscleactivelyanchors thecricoidcartilagebehind, enablingthethyroidcartilagetomovefreelyonthecricoidcartilageandtoproducefullstretchingofthevocalfolds.Becausethelarynxhasnotbeenraisedortightened,itisfreetovibrate,andbecauseitislowandthepharynxisfullyopen,itisabletoproducethepowerfulresonancesoftheheadvoice.

Figure3-7.Actionofsuspensorymusclesinheadvoice.Insetshowslinesofforceofthemuscles.

TheHyoidApparatus

Astheonlyboneintheregionofthethroatandtheonlyfree-floatingboneinthebody,thehorseshoe-shapedhyoidisacentralpointofattachmentforthemusclesofthethroat(Figs.3-8and3-9).Becauseofthehyoidbone’sshape,theGreeksnamed it after the letterupsilon.Youcan identify thehyoidbone ifyoupinchyour throatwith thumb and forefinger just above your larynx and swallow orwagyourtongue;youwillfeelthehyoidboneandlarynxmove.

Figure3-8.Hyoidapparatus.

Figure3-9.Styloidprocessandhyoidbone.

The central portion or body of the hyoid bone is thick; two horns projectbackward from the body and two smaller horns project inward and serve asattachments for the stylohyoid ligament. It is suspended from the styloidprocesses by the stylohyoid ligament and the stylohyoidmuscle,which is theone remaining elevator of the hyoid we haven’t yet looked at (Fig. 3-9).Stylohyoidarisesfromthebaseofthestyloidprocessand,passingforwardanddownward,insertsintothebodyofthehyoidbone.

Thehyoidboneservesthreeessentialpurposes.First,aswe’vealreadyseen,it

servesasanattachmentforthelarynxandforthemusclesthatelevateandlowerthelarynxinswallowing.Second,itisakeyanchorpointforthemusclesonthefloorofthemouththatdepressoropenthejaw.Third,itformsananchorforthetongueandisforthisreasonsometimesreferredtoasthe“tonguebone”(Fig.3-8).

Because the hyoid bone is the central attachment of the network of throatmuscles, themusclesof thethroataresometimesdividedintothosesupportingand moving the larynx and hyoid bone from above, called the suprahyoidmuscles, and those acting on the larynx and hyoid from below, called theinfrahyoidmuscles.Thesuprahyoidmusclesaremainlyontheundersideofthejawandskull;theypullthehyoidboneandlarynxupandforwardandmovethejaw(inset,Fig.3-8).

THEHYOIDBONE

Thehyoidboneistheonlyboneinthethroatregionandservesthreeessentialpurposes.

•First,itservesasanattachmentforthelarynxandforthemusclesthatelevateandlowerthelarynxinswallowing.

•Second,itisakeyanchorpointforthemusclesonthefloorofthemouththatdepressoropenthejaw.

•Finally,itprovidesastablebaseforthetongue(forthisreasonitissometimesreferredtoasthe“tonguebone”).

MusclesoftheHyoidBoneandJaw

Wehavenowlookedatseveraloftheelevatorsanddepressorsofthehyoidboneandlarynx.Thereareseveralmoreextrinsicmusclesattachingtothehyoidboneon the underside of the jaw that form part of the extrinsicmusculature of thelarynx.

The digastric is a sling-likemuscle that extends from the inner side of the

lower jaw to themastoid process on the base of the skull. It has twomusclebellies joined by a tendon that passes through a fibrous loop attaching to thesidesofthehyoidbone(Fig.3-11).

Figure3-10.Completehyoidmuscles.

Figure3-11.Falseelevatorsoftongue.

Styloglossusarisesfromthestyloidprocessesandattachestothesidesofthetongue(Fig.3-11).

Mylohyoid, a pair of flat and fan-shaped muscles, forms the floor of themouth. Its fibers run at a downward angle from the inner surface of thesymphysis andbodyof the jaw, joiningalong themidline at a tendinousbandand,atitsposteriorend,tothehyoidbone(Fig.3-10).

Geniohyoidliesjustabovemylohyoidandrunsfromtheinnersurfaceofthe

symphysisofthejawtothehyoidbone(Fig.3-10).

Thesemusclesperformtwocriticalfunctions.First,theydepressoropenthelower jaw; second, they elevate the hyoid bone and draw the hyoid bone andtongue forward during swallowing. Geniohyoid and mylohyoid are falseelevators of the larynx; the tendency to overuse these muscles can often bedetected in popular singers who appear to have a kind of double chin fromoverworking these muscles (Fig. 3-4). However, it is possible that thegeniohyoid muscle, which pulls the hyoid bone forward in swallowing, mayhavearoleinsinginghighnotes.Becauseofthedirectionofitspull,itseffectistorotatethethyroidcartilageforward,whichhelpstostretchthevocalfoldsandthus assists the cricothyroid. The genioglossusmay also assist in rotating thethyroidcartilageforwardandwideningthepharynx.

Theinfrahyoidmusclesattachmainlytothesternumanddepressorlowerthehyoid bone and larynx. The thyrohyoid muscle is a continuation of thesternothyroidmuscle andoriginates at theoblique lineof the thyroid cartilagejust infrontofsternothyroidandrunsverticallyupwardto insert into thebodyand cornua of the hyoid bone. These muscles, including the thyrohyoid, arecollectivelyknownasthe“strap”muscles(Fig.3-12).

Figure3-12.Sternohyoid,sternothyroid,thyrohyoid,andomohyoidarealldepressorsofthehyoidandlarynxandareknowncollectivelyasthe“strap”muscles.

A

CHAPTER4

THEMOUTHANDPHARYNX

stheopeningtothedigestivetract,themouthandpharynx,orthroat,haveanobviousandessentialroleintheprocessingoffood.Foodtakenintothe

mouthischewedbythemovablejaw,positionedbythetongue,anddrawndownthethroatintotheesophagusandstomach.Themouthandpharynxalsodoubleas an air passageway, which, as we’ve seen, require complex actions of thetongue,palate,andlarynxtoensurethatfooddoesnotgodowntheairway.

Themouthandpharynxalsoserveacrucial role in theproductionof soundand speech. Sounds produced by the larynx are shaped by the pharynx andmouth,whichformthevocaltract,tocreatedifferentvowelsounds,andchoppedupbythelips, teeth, tongue,andpalatetoproduceconsonants,resultinginthedistinct,articulatedsoundsofhumanspeech(Fig.4-1).

Figure4-1.Thevocaltract.

The mouth, or oral cavity, is separated from the nasal cavity by the hardpalate,whichformstheroofofthemouth.Themouthopensintothethroat,orpharynx.Thepharynx is roughly four and a half inches in length and extendsfrom the base of the skull to the bottom of the larynx. The pharynx can bedivided into threesections—thenasopharynx,oropharynx,and laryngopharynx(also known as the hypopharynx). The nasal section lies behind the nose andextends to the soft palate; the oral part extends from the soft palate to theepiglottis; the laryngeal section extends from the epiglottis to the cricoidcartilage,thelowestpartofthelarynx.Atthispointthecommonpassagewayforfoodandairsplitsintothetracheainfrontandtheesophagusinback(Fig.4-2).

Figure4-2.Thearticulators.

Thenasopharynx,whichservesonlyforthepassageofair,isnotvariableinshape. In contrast, the lower two-thirds of the pharynx can be constricted,dilated, and lengthened. These movements evolved first for the purpose ofswallowingandbreathing,buttheyalsofunctionaspartofthevocalmechanismandplayacriticalroleinthemodulationofthevoice.

MusclesoftheMouthandThroat

Thepassagewayofthethroat isenteredbythemouth, theopeningofwhichisprotectedbyorbicularisoris,themuscleformingthelips.Buccinatorformsthe

muscularwallsofthecheek(Fig.4-3).Itarisesfromthemaxillajustabovethemolars and from the mandible just below the molars, and from thepterygomandibular raphe, a ligamentous band of tissue that also serves as theattachment for the superior constrictor. Its fibers run horizontally to blendcontinuously into the fibers of orbicularis oris. Its function is to compress thecheektopositionfoodforchewing.

Figure4-3.Musclesofthemouthandthroat.

he constrictor muscles form the walls of the pharynx (Figs. 4-3 and 4-4).

TOriginatingoneithersideofthethroat,thesemuscleswraparoundtothebacktoformaseamalongthemidlineofthebackofthethroatcalledthemedianpharyngeal raphe.This seamattaches above to the pharyngeal tubercle, a

smallbumpon thebaseof the skull just in frontof the foramenmagnum(seeFig.3-2);likethehyoidboneandlarynx,theconstrictorsaresuspendedfromthebaseoftheskull.

Figure4-4.Constrictorsofthethroat.

The superior pharyngeal constrictor is continuous with buccinator; it arisesfrom the pterygomandibular raphe and the upper and lower jaws and curvesupward and backward to insert into themedian pharyngeal raphe.Themiddlepharyngeal constrictor, the smallest constrictor muscle, arises from the hyoidbone and fans out to attach to themedian raphe, its upper fibers overlappingthoseofthesuperiorconstrictor.Theinferiorpharyngealconstrictorarisesfromthe oblique ridge of the thyroid cartilage and curves upward and backward to

insert into themedian raphe, its upper fibers overlapping those of themiddleconstrictor. The lowest part of the inferior constrictor is the cricopharyngeusmuscle (Fig.4-3),which arises from the cricoid cartilage and, aswe’ve seen,functionsasoneoftheextrinsicmusclesofthelarynx.Thismuscleanchorsthecricoidcartilagedirectlybackwardtotheesophagus,whichbeginsatthispointjustbehindthecricoid.

The constrictors are responsible for swallowing. Though technically notconsidered as sphincter muscles, they constrict in turn during swallowing todrawthebolusoffooddownwarduntilitreachestheesophagus,whichconveysthefoodinperistalticwavesintothestomach.

TheFunctionofthePalate

The palate has two sections: the hard palate in front and the soft palate, orvelum,inback(Fig.4-2).Themainfunctionofthehardpalateistoseparatethenasalpassagewayfromthemouth.Thismakesitpossibleforaninfanttobreathewhilesuckling,andforanadult tochewfoodwhilestillbreathing throughthenose.

Thesoftpalateisamovablefoldthatfunctionsasavalvethatcancloseofforopenthenasalport, theopeningbetweenthenasalpassageandthepharynx.Ithangs behind the hard palate and forms an incomplete septum, or divide,between the mouth and pharynx. It is made up of an underlying flap ofaponeurotic or fibrous tissue attaching to the back end of the hard palate,formingakindofveilat thebackof the throat (hence thenamevelum,whichmeans“veil”inLatin).Musclefibersjoinintoitfromaboveandbelow,anditiscoveredwithmucousmembrane.

Thesoftpalatecanbelikenedtoadiaphragmthatiscapableofbeingraisedordepressed,andservesanumberof functions.When the softpalate is raised, itpressesuponthebackofthesuperiorconstrictorofthethroatataregioncalled“Passavant’s cushion,” sealing off the nasopharynx, or nasal port (Fig. 4-5a).When thebodyof the tongue is raisedandpressesagainst the softpalate, thiscloses off the oral cavity from the pharynx, making it possible to breatheexclusively through the nostrils while chewing (Fig. 4-5b). Since we aredesignedtobreathethroughournostrils(whichfilter,moisten,andwarmtheair)and to feed throughourmouths, this isalso thebasic“restingposition”of the

tongue during normal breathing.When the nasal port is closed and the velumand tongue create an oral seal, both the nasal and oral cavities are sealed offfromthepharynx;thishappenswhenweholdourbreathandswimunderwater.Inthiscase,neitherwaternoraircanpassthroughthenasalandoralcavitiesintothepharynx(Fig.4-5c).Duringswallowing,thepalateisfirstraisedinordertoclose the nasal port and allow food to enter the pharynx. It is then depressedagainst the raised tongue to drive the food downward during the act ofswallowing.

Figure4-5.Valveactionofthepalate:a.Velopharyngealclosureofsoftpalateagainstbackofpharynx;b.Oralsealformedbybackoftonguecontactingsoftpalate;c.Bothactionscombiningtosealnasalandoralpassages.

TheMusclesofthePalate

There are fivemuscles of the palate.Acting on the palate from above are themuscles that tightenandelevate thepalate (Fig.4-6).Levatorvelipalatini isathickmusclethatarisesfromthetemporalbonesoneithersideoftheskulland,

passingobliquelydownwardandinward,joinsintothesoftpalateatitsmidline,whereitblendswiththefibersofthemuscleontheoppositesidetoformakindof sling that supports the soft palate. Its function is to move the soft palateupwardandbackward,closingthevelopharyngealvalveornasalport.Whenweyawnordeepen thevoice,whichraises thepalate, it is thismuscle thatcomesintoplay—acrucialoneforvoiceusers.

Figure4-6.Elevatorsofthepalate.

Tensorvelipalatinidescendsvertically from thesphenoidboneof the skull,runs round a bony protrusion called the hamular process, and inserts laterally

intotheaponeurosisofthepalate(Fig.4-6).Becauseitinsertshorizontallyintotheveilofthesoftpalate,itscontractiontensesorstiffenstheveilofthepalatewhenthetonguepressesupagainstitinswallowing.Italsoactsantagonisticallytotheelevatorofthepalatebystiffeninginoppositiontoit,helpingtocreatethearchesofthepalate.

The salpingopharyngeusmuscle is a diminutivemuscle that originates fromthe Eustachian tube near the inner ear and, passing downward, joinswith thefibersofthepalatopharyngeusmuscle.Thismuscleassistsinraisingthepharynx(Fig.4-6).

The uvula is the visible structure hanging down from the soft palate justbehind the hard palate. It is supported by muscle fibers but has little realfunction.

Therearetwodepressorsofthepalate(Figs.4-6and4-7).Justinfrontoftheuvulaare the twoarchesorpillarsof thesoftpalate,whichcanbeeasilyseentowardthebackoftheoralcavity.Palatoglossus,whichformstheanteriorpillar,arisesfromthesoftpalateoneithersideoftheuvulaand,slopingdownwardandoutward,insertsintothesidesofthetongue.

Figure4-7.Depressorsofthepalate.

Palatopharyngeus,whichformstheposteriorpillar,arisesfromthesoftpalatebehindthepalatoglossusmuscleand,passingoutwardanddownward,joinswiththefibersofthestylopharyngeusmuscletoinsertintotheposteriorborderofthethyroidcartilage.Palatopharyngeusandpalatoglossusdepress thepalateduringeatingandswallowing.Theyalsohelp toelevate the tongueand larynxduringswallowingandvocalization.

THEACTIONOFSWALLOWING(DEGLUTITION)

Swallowing is a complex activity involving muscles of the tongue,palate, and the elevators and depressors of the hyoid bone, larynx,andpharynx. It beginswith theoral preparatoryphase,duringwhichfood is chewed, then positioned by the tongue and the cheeks, andformed intoamass, calledabolus, that is small enough to swallow.Thethreephasesofdeglutitioncanbedescribedasfollows:

1.Inthepreparationphase,themusclesoflipsandcheekscontracttomove the food into position on the tongue. The tongue contractsagainst thehardpalate todrive thebolusof food through the fauces(archesofthesoftpalate).Thesoftpalateelevatesasthetensorvelipalatini, levator veli palatini, and palatopharyngeus contract, drawingthevelumupandbackagainstthepharyngealwall.

2. The swallowing phase begins reflexively when the bolus passesthroughthefaucialarches.First,velopharyngealclosuretakesplacetoprevent aspiration of food into the nasal cavity (levator veli palatini).Second, the larynx closes tightly. Third, the pharyngeal constrictorscontractinsequence.Fourth,thelarynxisdrawnforwardandupwardbythetonguemusclesandelevatorsofthehyoidbone.

3. In the thirdstage, thebolus is received into theupperesophagus,which conveys the food through peristaltic action in which theesophagus relaxes and contracts in a wave-like motion to draw thebolusintothestomach.

TheArchedPalate

The action of the palate during speaking and singing is variable but, on thewhole,singingrequiresthatthepalatebearchedorraised.

Aswehavejustseen,viewedfromtheoralcavity,thepalateformsarchesthatrundownintothetongueandpharynx;thesearchescaneasilybeseencurvingdown from the uvula,which is situated at the apex of these pillars.When thethroatistight, thetonguetendstoberaisedandthejawalsotendstobepartlyclosed (Fig. 4-8b). Conversely, when the arches of the palate are raised, thetonguedropsandthelarynxdescends,openingthethroat(Fig.4-8a).

Figure4-8.Thesoftpalate:a.Arched;b.Depressed.

The arching of the palate is due mainly to the action of the tensors andelevatorsof thepalate,whichraise thearches.Thepalateacts inopposition tothetongue,larynx,andhyoidbone.Whenthepalateisdepressed,thetongueandlarynxareelevated,constrictingthethroatasinswallowing.Whenthepalateisraised,thetongue,hyoidbone,andlarynxarelowered,openingthethroat.Thishappens during the beginning stages of swallowing, and when we inhale oryawn.Withaminimalamountofpractice,onecanlearntoraisethearchesofthepalateatwill,bringingthemunderconsciouscontrol.

Archingthepalatehasacrucialeffectontheshapeofthevocaltract.Becausethe palate forms a septum separating the oral cavity from the pharynx, adepressed or collapsed palate separates the oral and pharyngeal cavities. Incontrast,archingthepalateunifiestheoralcavityandpharynxbymakingthemintoacontinuousresonatorandisthusacrucialelementinskillfullyshapingthevocaltractinsinging(seeFigs.4-12aandb).

In singing, the nasal port is mainly kept open, particularly during vowelproductionandwhensingingintheupperregisters.Thismeansthatthepalateisactuallykeptfairlylow,nothigh,assingersoftenclaim.

TheTongueandItsFunction

Thetongue,or lingualregion, iscomposedof intrinsicmusclefibers that formthebodyordorsumofthetongueitself,aswellasfourextrinsicmuscleswhosefibers joinwith thedorsumof the tongueandmove it frompointsoutside thedorsumofthetongue(Fig.4-9).Thetongueliesat thefloorof themouth,andthehyoglossusandgenioglossusmusclesattachittothehyoidbone.Thetongueisdivideddownitsmidlinebyafibrousseptumandismadeupofseverallayersof muscle fibers running in various directions. The superficial layer is thesuperior longitudinal muscle. The middle layer is composed of vertical andtransversemuscles.Thedeepestlayeristheinferiorlongitudinalmuscle.Theseintrinsicmuscles interminglewith the fibers of the extrinsicmuscles that joininto the dorsum of the tongue—in particular, the styloglossus and hyoglossusmusclesonthesidesofthetongueandthegenioglossusmuscleonitsunderside.This complex arrangement of intrinsic fibersmakes it possible to shorten thetongue, to form it into a convex or concave shape (with the tip of the tongueturnedupward),tonarrowandelongatethetongue,ortoflattenandbroadenit.Inconjunctionwiththeextrinsicmusclesthatmoveandpositionthetongue,thiscomplex arrangement of fibers also makes it possible to form the sounds ofspeech.

Figure4-9.Thetongueanditsmuscles.

Aswehaveseen,theextrinsicmusclesofthetongueliebelowthedorsumandmove the tongue in various directions (Fig. 4-9). The first of these extrinsicmuscles is the hyoglossus, which originates from the hyoid bone and passesvertically upward and forward to insert into the sides of the tongue.Genioglossusrunsverticallyfromtheinnersideofthesymphysisofthejawandspreadsoutinafan-likeshapeoneithersideofthemidlineofthejawtoinsertinto theundersideof the tonguealong itswhole lengthand to thehyoidbone.The styloglossus muscle originates at the styloid process and joins into bothsidesofthebodyofthetongueandwiththefibersofthehyoglossusmuscle.Thestyloglossusmuscledrawsthetongueupwardandbackward.Thepalatoglossusmuscle arises from the softpalate and,passingdownand forward, inserts intothesidesofthetongue.Itsfunctionistodrawthebaseofthetongueupwardandto compress the palate during swallowing. The extrinsic muscles make itpossibletomovethetongueasawhole,asinsuckingorpositioningfoodinthemouth,andplayanimportantroleintheactionofswallowing.

PositionoftheTongueinSinging

Insinging, the throat functionsbestwhen it isopen.Thismeans,amongotherthings,thatthetonguemustremainfairlylowinthemouthwiththetiptouchingthelowerteeth,thetonguelowestinfront,andthejawopenandrelaxed.Thisiseasiest toexperiencewhenproducing the“ah”vowel,which involves the leastmanipulationofthetongueandisthereforethedefaultvowelinsinging.Inthisrelaxed position the tongue also tends naturally to form a groove down themidline(Fig.4-10).

Figure4-10.a.Positionofthetongueduringsinging:openthroat;b.Raised

positionoftongue:closedthroat.

Thetongueisalsothemostimportantfactorintheformationofvowels.Thedefaultvowelis“ah,”becauseintheabsenceoftryingtoformavowel,“ah”iswhat you’ll get.Theother vowels involve a changeof positionof the tongue.Singerstendtochangeonlythetonguepositionandnottoinvolvethelipsandmouthtoomuch,asthesecauseunnecessarytension(Fig.4-11).

Figure4-11.Thepositionofthetonguedeterminesthekindofvowelthatisproduced.Inthecolumnontheleft,thetongueispositionedforward,producing

theso-called“front”vowels(ee,aasin“hay,”ah);inthecolumnontheright,thetongueispositionedtowardthebackofthethroat,producingthe“back”vowels(oo,oh,ah).

Producingtheopenqualityrequiredinsingingisalsorelatedtovowelsounds.Tomaintainanopenthroat,singersoftenalterspokenvowelsounds,tendingtomakethemopenanddarker,aswhenweyawnandopenthethroatonthevowelsound.Incoveredsinging,thelarynxisloweredsothatboththeapertureto,andthelowestpartof,thelarynxarewidened.Sotongueposition,vowelformation,andtheloweredlarynxareallcrucialfactorsinsinging.

TheLowLarynxandWidenedPharynx

Thefinalelementofanopenthroatisthelowpositionofthelarynx.InChapterThree,wesawthataskilledsingerdoesnotappreciablyraisethelarynxbut,byengagingthesuspensorymusclesofthelarynx,isabletomaintainthelarynxinalowpositionevenwhilesinginginthehigherregisters.Thiskeepsthelarynxfreeinitsoperationsothatitdoesnotconstrictasthepitchrises.Italsoassiststhelarynxinproducingasupportedfalsettotoneandheadvoice.

Maintaining a low larynx has another effect as well: it lengthens the vocaltract andwidens the lower part of the pharynx.This tends to produce amoreopen vowel quality,which sounds darker as a consequence. Sometimes called“covering,”thisqualityisacriticalpartofclassicalvocaltrainingandislargelyduetotheactionofthesuspensorymuscles,whichtendtoopenthethroatasthelarynxislowered.Oneofthemusclesresponsibleforopeningthepharynxisthepairedstylopharyngeusmuscles,whichare fartherapartat theirorigins thanattheirinsertions(seeFig.4-4),andwhichthereforepullthewallsofthepharynxapart as they pull upward, dilating the throat. Their action is opposed by thedepressorsofthelarynx,whichmaintainthelowpositionofthelarynxandthuslengthenthevocaltractasitwidens(Fig.4-12).

Figure4-12.a.Raisedlarynxandconstrictedthroat;b.Loweredlarynxandopenthroat.Noticethatin(a),thesoftpalateandlarynxmovetowardeachotherandthepharynxisshortened;in(b),thesoftpalateandlarynxmoveawayfromeachotherandthepharynxislengthened.

Lengthening and widening this part of the vocal tract is one of the mostimportantelements inmodulatingthevoice.Thesoundthatemanatesfromthevibratingvocalfoldsisacomplextonecomposedofafundamentalfrequency,orpitch, and a number of overtones, which give the tone a rich and complextimbre.The cavities above the larynx act as a flexible resonator for this vocalsignature,augmentingcertainfrequenciesandattenuatingothers.Thevocaltract

hasseveralresonancefrequenciesthatmaximallyaugmentthevocalsignal,andthe lowered larynx andwidened pharynx in particular produce a formant, notfoundintheaveragespeakingvoice, thatmatchesperfectlywiththefrequencyofthevibrationsfromthelarynx.Thiscreatesthepowerful,ringingtonesoftheoperaticvoice thatcancarryoveranorchestraand in largespaces.Sometimescalled the “singer’s formant,” this quality is prized by classical and operaticsingersandachievingitconstitutesalargepartoftheirtraining.

A

CHAPTER5

THEFACEANDJAW

lthough the facial bones and muscles do not play a direct role inphonation, they nevertheless form a crucial component of the vocal

instrument. There are several reasons for this. First, the facial muscles areorgansofcommunicationandexpression.Second,weoften“collapse”thevocalmechanism as part of losing tone in the face, sleeping with the mouth open,usingthevoiceina“heavy”way,collapsingthepalate;asaresult,manyvoiceusersdevelopthroatinessoftoneandothervocalproblemsovertime.Toningthefacialmusclesisanessentialcomponentin“activating”thevocalinstrument,asmanysingers,whomaintainhealthyandyouthfultoneinthefacialmuscleswellintooldage,knowwell.Third,vocalfunctionisdirectlyinfluencedbytoneofthefacial muscles, which have indirect reflex connections with the larynx andthroat;learningto“place”thevoicebytoningthefacialmusclescanprofoundlyinfluenceboththelarynxandthethroat.

Thefacialmusclesaredifferentfromotherskeletalmusclesbecausetheydonot attach from one bone to another but, in most cases, arise from bone orcartilageand insert into the integument,orskin tissue,oftenblendingwith thefibersofothermuscles.Thisgivesthemtheabilitytoproducefacialexpressionsbymovingtheskin,tonarroworwrinkleareasofskinandtissue,andtomoveorcontractapertures,as in thecaseof theareaaround theeyes. Inparticular, theareas around the mouth, the lateral region of the orbits of the eyes, and theregionbetweentheeyesareconvergencepointsformuscleswhosefiberstendtoblendwithoneanother.Becausethefacialmusclesareoftenoverlappingandarecontinuous with the fascia covering the face and neck, they form a movablesheetofconnectivetissuecoveringtheentireface(Fig.5-1).

Figure5-1.Musclesoftheface.

TheMask

Perhapsbecausesingersexperiencevibrationsinthenasalregion,thisregionofthe face—often referred to as the singer’s “mask”—has often been consideredoneofthekeyvocalresonators.Althoughneitherthenasalbonesnorthenasalcavities actually participate in the resonance of the voice, the practice of“placing” the voice in the mask does affect the function of the larynx andproducemorefocusandringinthevoice.The“mask”ismadeupmainlyofthemaxilla,thenasalbones,andthelowerpartofthefrontalbonewherethesinuses

arelocated;singersareusuallyawareofthisregionwhilesinging(Fig.5-2).

Figure5-2.Themask.

TheNostrilsandNasalCavity

The nostrils are the primary breathing channel during normal breathing. Thenostrilsopenintothenasalcavitiesorfossae,whichareformedbythewingedturbinatebonesoftheskull(alsocalledconchae)separatedbyaseptumintotwoseparate cavities (Fig. 5-3). These cavities, in addition to being lined with

mucous membranes with a rich vascular supply, separate into olfactory andrespiratory sections. Two apertures (or choanae) at the posterior part of thesecavitiesopenintothenasopharynx.Inadditiontofunctioningasasensoryorganforsmell,thenostrilsmoisten,filter,andwarmtheairtakenintothelungs.

Figure5-3.Nasalcavity.

MusclesoftheNostrils

Dilatingandactivating thenostrils is associatedwith inhalation,which in turn

tends to open the throat. There are three dilators and three depressors of thenostrils (Fig. 5-4). Levator labii superioris alaeque nasi (from Latin, meaning“elevatoroftheupperlipnexttothenose”)originatesfromtheupperportionofthemaxillaneartheinnermarginoftheorbitoftheeye.Anglingdownwardandoutward,someofitsfibersattachtotheupperlipandsometothecartilageoftheala nasi (the wing-like portion of the nostril, from the Latin ala, meaning“wing”). It elevates the upper lip, and elevates and dilates the ala, as inproducingasneer.

Figure5-4.Musclesofthenose.

Justbeneathlevatorlabiisuperiorisalaequenasiisdilatatornarisposterior.Itarisesfromthemarginofthenasalnotchofthemaxilla(seeFig.5-7)andinsertsintotheskinnear themarginof theala.Dilatatornarisanteriorarisesfromthecartilageof thealaandattaches to the skinnear itsmargin.Thesemuscles, astheirnamessuggest,dilatethealae.

Thenasalismuscle,whichhasatransverseandalarpart,isthecompressorofthe nostrils. The transverse part, also known as compressor nasi or naris,originatesatthemaxillanexttotheala;itsfibersexpandupwardandinwardjustbehindthenostrilsandblendintothefasciaofthecartilageofthenose,whichiscontinuouswiththatoftheprocerusmuscleonthebridgeofthenose.Thealarpartof thenasalismuscle (inGray’s, theouterpartof thedepressoralaenasi)arises from the maxilla below the origin of the transverse part of the nasalismuscleandinsertsintotheseptumandposteriorpartoftheala.Thefunctionofthesetwomusclesistodrawthealaedownwardandtoconstrictthem.

The depressor septi nasimuscle (inGray’s, the inner part of depressor alaenasi) arises from the maxilla under the nose and inserts into the septum andposterior part of the ala. Its function is to draw the alae downward and toconstrictthem.

Compressornariumminorisatinymusclearisingfromthecartilageofthealaandattachingtotheskinatthetipofthenose.Italsodepressesthecartilageofthenoseandcompressesthenostrils.

Theactionofthesemusclesisrelatedtothesoftpalateandopeningthethroatinsinging.Compressingthenostrilstendstobeassociatedwithdepressingandcollapsing the palate; dilating the nostrils and sneering, which are associatedwith inspiration, tend to raise the palate and dilate the pharynx. Think ofsneering and smelling something pungent, and notice how this enlivens anddilatesthenostrilsandevenhelpstoopenthethroat.

TheEyesandForehead

Although the eyes are organs of perception, they are also expressive ofmoodandcommunicatefeelings,andareinthissensecrucialtothevocalorgan.Thereare several muscles of the eyes and forehead (Fig. 5-5). The key foreheadmuscle,frontalis,drawsthescalpback,raisingtheeyebrowsandwrinklingthe

forehead.Itisactuallypartofatendinoussheetthatrunsrightoverthescalptothe occiput in back, where there is another section of muscle tissue (notpictured).

Figure5-5.Musclesoftheeyesandforehead.

Corrugatorsuperciliiliesinbetweentheeyebrows;itisthefrowningmuscleandcausestheverticalwrinklesintheforehead.Itarisesfromtheinnerpartofthebrow,orsuperciliaryridgeofthefrontalbone,runningoutwardtoinsertintotheskinabovetheorbit.

Procerus (also called pyramidalis nasi) lies between the eyebrows. It arisesfrom the cartilage on the upper part of the nose and the fascia over the nasalboneandinsertsintotheskinandthemusclefibersofthefrontalismuscle.Thismuscledrawstheeyebrowstogetherandalsoproducesfrowning.Thefibersofthe frontalis muscle are continuous with corrugator supercilii, procerus, andorbicularisoculi.

Surrounding the orbits of the eyes and eyelids is a sphincter muscle,orbicularis oculi. Its outer ring of fibers is the orbital part; the inner ring,coveringtheoutereyelid,isthepalpebralpart.Orbicularisoculiarisesfromthefrontalandnasalpartofthemaxillabone,itsfibersfanningoutaboveandbelowto cover the eyelids and to encircle the orbits of the eyes to the cheek andtemples.Itsfunctionistonarrowandprotecttheareaaroundtheeyesand,alongwith the frowningmuscles, to produce squinting.Thepalpebral portion closesthe eyelids. Continual contraction of the orbital region tends to producepermanentsquintingoftheeyes,drawingtheeyebrowovertheeyelid.

Becausewe communicatewith the face and eyes, habitual frowning,worry,and seriousness of demeanor cause the eyes to lose tone and expressiveness,which in turn signifies loss of energy or collapse of the vocal organ. Theorbicularis oculi muscles become habitually tightened from squinting andtension.Wealsotendtobecome“glazedover”andhypnoticwhenconcentratingonourworkorsittingatacomputer,whichhardenstheeyesandlowersmuscletonearoundtheeyes.Softeningandbrighteningtheeyestendstorelaxandtonetheareaaroundtheeyesandisassociatedwithamorepositivementalattitudeandactivatedvocalinstrument.Althoughassociatedwithsmiling,thebestwaytobringthisaboutisnottoforceasmilebutbythinkingofsomethinghumorousor touching, by making eye contact with another person, or by lookingattentivelyatanobject.

TheCheeks

The cheekmuscles are also associatedwith activation of the vocal instrumentandwithamorefocusedtone.Thereareseveralmusclesaroundthecheekandtheareaabovetheupperlipthatrelatetofacialexpressionssuchassadnessandlaughing(Fig.5-6).Levatorlabiisuperiorisarisesfromthelowermarginoftheorbit formed by the zygomatic and maxilla bones. It passes downward andinwardtoconvergeintothemuscularfibersaroundthemouth.Itsfunctionisto

elevatetheupperlip.

Figure5-6.Musclesofthecheekandmouth.

Levator anguli oris arises from the ridge of the canine tooth on themaxillabone,justwherethecheekbone,orzygomaticbone,beginstoprotrude.Itpassesdownwardtoblendintothemuscularfibersoforbicularisorisandzygomaticusmajor,around themouth. Its function is to raise theangleof the lips.Youcanfeel the effects of these muscles if you crinkle the nose, which engages theelevatorstobunchupthecheeksjustbelowtheeyes.

Zygomaticus minor arises from the zygomatic, or cheekbone, and passesdownward and inward to converge, with levator labii superioris, into themuscularfibersoforbicularisoris.Itdrawsthemouthupwardandslightlyback,asinexpressingsadness.

Zygomaticusmajorarisesfromthearchofthecheekbonewhereitcurvestoformthelateralplaneoftheface.Itpassesobliquelydownwardandforwardtoinsertintoorbicularisorisnexttolevatorangulioris.Itdrawsthecornersofthemouthback,asinlaughing.Wherezygomaticusmajororiginatesinfrontoftheear,ittendstobecontinuousalongthelateralplaneofthefacewiththemuscleinfrontoftheear,auricularisanteriormuscle,aswellasthetemporomandibularjoint.

Becauseofthetendencytoloseexpressivenessintheface,itisusefultotonethecheekmusclesby“brightening”theeyesandraisingorroundingthecheeks.Toningtheeyesandcheekmuscleshelpstoactivatethesuspensorymusclesofthelarynxandto“place”thevoiceforward,givingitabrightertone.Thisalsohelps to maintain healthymuscle tone and youthfulness in the facial muscleswellintooldage.Whenmusculartensionintheeyesandcheeksisreduced,youcanfeelthemusculatureofthefacebecomemobileandfreerightaroundtothesidesofthefaceandjaw,whichhelpstoopenandtonethemusclesofthepalateandthroat.

TheJawandTemporomandibularJoint

Thejawormandible(alsocalledtheinferiormaxillarybone)isthelargestboneof the face (Fig.5-7).The section of the jaw that forms the chin is called thesymphysis;themainlineofthejawisthebody;theupwardextensionthatformsthe jointandattachments formuscles is the ramus.The ramusdivides into thecoronoidprocessinfrontandthecondylarprocessinback.Thecoronoidprocessservesasthepointofattachmentforthetemporalismuscle;thecondylarprocessarticulateswiththetemporalbonetoformthetemporomandibularjoint.

Figure5-7.Thejawandtemporomandibularjoint.

The temporomandibular joint is located directly in front of the externalacoustic meatus, the opening for the ear (Fig. 5-7). Directly in front of thisopeningisadepressioncalledthemandibularfossa.Thecondylesofthejawsitwithinthisdepressionand,whentheyrotate,producethebasichingingactionofthejaw.Thecondylescanalsoglideforwardinrelationtothemandibularfossasothatthejawasawholecanmoveforwardandback.Whenonecondylemovesforwardandtheothermovesbackward,thejawproducesagrindingmotion.

The temporomandibular joint is basically aglidinghinge joint.Between themandibular fossaand thecondyle isacartilagecalled thearticulardisc.On itslowersurfacethearticulardiscformsaroundedsurfacethatcradlesthecondyle,whichisabletorotatewithinthisdisc,producingthehingingactionofthejaw

(Fig.5-8a).Thisdisc,however,isnotfixedtothetemporalbonebutislubricatedonitsuppersurfacewithsynovialfluidsothatitcanglideforwardinrelationtothemandibularfossa,bringingthecondyleandjawwithit(Fig.5-8b).

Figure5-8.a.Partialopeningofthejawforspeaking:thejawhingesatthejoint(downwardarrow)withoutmovingforwardinspace;b.Wideropeningofthejawforsinging:thejawswingsormovesforwardinrelationtothetemporalbone(forwardarrow)asithingestoopen(downwardarrow).

Thetemporomandibularjoint,then,isreallytwojoints:thehingejointformedby the articulation of the condylewith the articular disc, and the gliding jointformed by the articulation of the articular disc with the temporal bone. Botharticulations are lubricated, and the entire joint is enclosed within a capsularligamentandsupportedbytwootherligaments.Thejawisalsosupportedbythestylomandibularligament(notpictured),whichextendsfromthestyloidprocessofthetemporalbonetotheangleofthejaw.

PositionoftheJawinSinging

Normalspeechdoesnotrequirethatthejawbeopenedwidely;thecondylesofthejawrotatewithinthearticulardiscbutnoothermovement takesplace.Forthe purposes of singing, however, the jaw should openmore fully so that thesound is not blocked and to create a large enough oral cavity for efficientresonance.Inthiscasethejawmustnotonlyhingeatthecondylebutmustalsoglide forward; otherwise the condyle gets jammed and the jaw cannot open

freely(Fig.5-8b).Whenthecondyleglidesforward,youcanfeelapocketopeninfrontofthelowerear.Allowingthejawtoopenfreelyisunfamiliartomanyvoiceusers,whohabituallytightenandretractthejaw.

MusclesoftheJaw

Threemusclesproduce thegrinding,chewing,andsnappingactionsof the jaw(Fig.5-9).Temporalis,whichisabroad,powerfulmusclethatoriginatesbroadlyat the temporal regionon the sideof theheadandconverges to insert into thecoronoidprocessofthejaw,ismainlyresponsibleforthesnappingactionofthejaw.Themassetermuscleoriginatesatthecheekboneandinsertsintotheramusofthejaw.Itsfunctionistoraisethelowerjawandtoclampitshut.

Figure5-9.Musclesofthejaw.

Thelateralandmedialpterygoidmusclesarisefromthecheekboneandpalateareasoftheskull.Themedialpterygoidinsertsintotheramusandangleofthejawbone.Thelateralpterygoidinsertsintotheinterarticularfibrocartilageofthetemporomandibularjoint,andistheprincipalagentindrawingthejawforward.When acting alternately, the function of the pterygoidmuscles is to grind thejaw. All three of the jaw muscles acting together produce the movements ofchewingandgrindingfood.

Threemusclesdepressoropenthejaw,allofthemontheundersideofthejaw

(Fig. 5-10). Digastricus, which means “having two bellies,” originates at themastoid process, runs through a loop on the hyoid bone, and continues on toinsertintothejaw.Mylohyoidandgeniohyoidformthefloorofthejawandalsorelate the jaw to thehyoidbone.These twomuscles form the floorof the jawandaresometimesreferredtoasthe“diaphragmofthejaw”(Fig.5-11).Singersoftenfocusonthelargeclosersofthejawwhenseekingtoreleasethejaw.Butthese jaw muscles evolved as part of the throat musculature attaching to thehyoid bone and sympathetically tighten in response to tension in the throat,whichiswhythethroatmusclesaretherealkeytoreleasingthemusclesofthejaw.

Figure5-10.Depressorsofthejaw.

Figure5-11.Thediaphragmofthejaw.

A

CHAPTER6

THEEVOLUTIONANDFUNCTIONOFTHELARYNX

nyonewhohasmadeevenacursorystudyofthehumanlarynxislikelytoassume, based on how beautifully suited it is for producing sound, that

mostofitsremarkableandintricatefeaturesevolvedmainlyforthispurpose.Infact, most of the features of the larynx evolved for reasons other than vocalcommunication. To better understand the design of the larynx and voice ingeneral,let’slookinthisfinalchapteratsomeofthestagesbywhichthelarynxandvoiceevolved.

TheOriginoftheLarynx

Theoriginal functionof the larynxwas toprotect theairwayinfish thatcouldbreathe air. As we all know, fish do not normally breathe air but take theiroxygen out of the water flowing through their gills. Certain species of fish,however,developedlungsacssothattheycouldgulpinairwhentheycametothe surface, or survive in the mud during dry periods. These lung sacs wereaccessedby a short passageway that opened from the floor of thepharynx. Inorder to keep water or food from entering this air passage, the opening wasprotectedbyasimplevalve,orcircularsphinctermuscle, that remainedclosedwhenthefishwasunderwaterorfeeding(Fig.6-1).Thehumanlarynx,althoughgreatlymodifiedfromthisoriginalform,stillfunctionsasasphinctertocloseoffandprotecttheairway.

Figure6-1.Thelarynxfunctionsasasphinctertocloseofftheairway.

EvolutionoftheCartilagesandMusclesoftheLarynx

Infishthathavelungs,thereisnowayofactivelyopeningthesphincterofthelarynx;duringperiodswhenairwasneeded,thesphinctersimplyrelaxedandairflowed into the lungs. Animals on land, however, needed to more activelycontroltheopeningandclosingoftheglottis.Thiswasanabsolutenecessityinanimalsthatbreathedbysuction,sincethesuckingactionoftheribcagepulledthelipsoftheglottis,ortheopeningofthelarynx,togetherandthereforehadtobecounteractedwithmusclesandscaffoldingthatcouldactivelyholditopen.

Inmammalsthatdevelopedasophisticatedlarynx,thesechangeshappenedinseveral stages. First, muscle fibers attaching close to the sphincter shifteddirectioninsuchawaythattheycouldactivelypullonthemarginsoftheglottisanddilateoropenit.(Theseweretheprecursorsoftheposteriorcricoarytenoid

muscles.)Next,cartilagesappearedalongthemarginsoftheglottis;theseservedasanchorsforthedilatormuscles,makingthepullofthemusclesmoreefficient(Fig.6-2).

Figure6-2.Sphinctermusclesanddilator.

Part of the lateral cartilages formed into the arytenoid cartilages at theposterioroftheglottisandservedasattachmentsforthevocalfolds;otherpartsof the cartilage on either side fused to form the cricoid ring at the top of thetrachea.Thearytenoidcartilagesformedjointswiththecricoidcartilage;whenthearytenoidcartilagesswiveled,therimoftheglottiscouldbeactivelyspreadapart.

Thethyroidcartilagealsoappearedinevolutionasanoutgrowthofthecricoidcartilage. At first the two cartilages were fused, but in higher mammals theyseparatedtoformahinge.Becausethethyroarytenoidmusclenowattachedatitsfrontend to the thyroidcartilage (insteadof thecricoid), themovementof thethyroidinrelationtothecricoidcartilageshortenedtheglottisandfacilitateditsclosure.

With the appearance of arytenoid cartilages andmuscles thatmoved it, theglottis was now closed by three sets of muscles and opened by one. The

thyroarytenoidmusclesformedthelipsoftheglottisand,bycontracting,closedofftheglottisdirectly.Twoothermuscles,thelateralcricoarytenoidsonthesideof the cricoid and the transverse arytenoids in back, pulled parts of thearytenoids together to close the glottis. Although modified from its originalform, these three muscles still formed a sphincter that closed the glottis; theposteriorcricoarytenoidformedthedilator(Fig.6-3).

Figure6-3.Furtherdevelopmentofthemusclesthatdilateandclosetheairway.

The larynx now had many of the basic features we see in humans. Thearytenoid,thyroid,andcricoidcartilagesservedasaframeworkformusclesthatefficiently opened and closed the glottis. The posterior cricoarytenoid muscleabducted thevocal folds.The thyroarytenoidmuscles,orvocal folds,were thetensors of the glottis; the lateral cricoarytenoids and the transverse arytenoidsweretheclosers;andthecricothyroidmuscleswerethestretchers.Beingabletoboth open and close, the larynx now performed the two vital functions ofprotectingtheairwayandensuringaconstantsupplyofair,butitwasalsowell

suitedasasound-producingorgan.

ExtrinsicMusclesoftheLarynxandDeglutition

One of the crucial roles of the extrinsic muscles of the larynx is duringdeglutition, or swallowing. Inmost reptiles, the larynx lies on the floor of thepharynx and does not obstruct the passage of food, which is bolted in largepieces.Inlandanimals,thelarynxtiltedupinbacksothattheairwaywasinadirect linewith themouth,whichplaced the tracheaandesophagusparallel toeach other. This made it easier to get a constant supply of air, but it alsoincreased the danger of aspirating food, since the open airway now laymoredirectly in the path of the bolus of food. To protect the airway duringswallowing,thelarynxnownotonlyclosed;itwasalsoraisedbythesuprahyoidmuscles, which pulled it up under the tongue. In snakes, the larynx is pulledrightuptotheteeth,sothattheairwayremainscompletelyopenevenwhileitshugepreyisslowlyworkeddownitsthroat.

ThePalate,Epiglottis,andNasalPassages

Inallanimalsthatbreathe,thenasalpassagecommunicateswiththeairtractsothattheflowofairinandoutofthelungscanbringmoleculesintotheolfactoryorgan. In reptiles, air breathed through the nostrils comes directly into thepharynx(Fig.6-4a).Inmammals,asecondarypalateformedbetweenthenasaland oral passages in order to separate the food and respiratory passageways,makingitpossibletobiteorchewwhilecontinuingtobreathe(Fig.6-4b).Thisseparationbecameespecially importantforherbivorousmammalsandsucklinginfants, which feed for long periods and must be able to continue to breathewhile doing so. To make it possible to swallow while breathing, herbivoresdeveloped a large flap, or epiglottis, at the front of the larynx. The epiglottisformsacollarwithhighwallsalongthesidesofthelarynx,makingitpossibleforliquids(orvegetablesinliquidform)topassaroundthesidesofthelarynxand into theesophaguswithoutanydangerofaspirating fluids into theairway(Fig.6-5).

Figure6-4.Palateandseparationofnasalandoralpassageways:a.Reptile;b.Mammal.

Figure6-5.Epiglottisandpalateinherbivoreshowinghowepiglottislinkswithpalatetocloseoffmouthtobreathing.

Theepiglottisisalsoabletomakedirectcontactwiththepalate,blockingthepassageof air through themouth anddirecting it through thenose so that thesense of smell canbe constantlymaintained, evenwhile feeding. (Contrary topopular belief, the epiglottis is not primarily designed to prevent food fromentering the larynx; that is the jobof the larynx.) Inhumans, the epiglottisnolongerconnectswiththepalateandsohaslostitsoriginalfunction.Butwearestilldesignedtobreathemainlythroughthenostrils.

DesignoftheVocalFolds

Anothermajordevelopmentintheevolutionofthelarynxasasound-producingorgan camewith the separation of the thyroarytenoidmuscles into upper andlowerfolds.Four-footedanimalsrequireareadysupplyofairforrunningbutdonotneedtoexerttheirforelimbsinastrenuousway.Arborealanimals,however,musthangand swingby theirpowerful forelimbs.Using the arms in thiswayexertsa tremendouspullon the ribs,whichmustbestabilized inorder for thearm muscles to support the body through the torso. To facilitate this, thethyroarytenoidmusclesbecomeseparatedintoupperandlowersections.

Theupperfoldsbecamedownturnedandthereforeactedasanexitvalvethatpreventedtheescapeofairwhenthelungswerefilled(Fig.6-6a).Thismadeitpossible,whenfillingthelungswithairandthentryingtoexhalebycontractingthe ribs and abdominalmuscles, to raise intrathoracicpressure. (This is usefulalsoduringdefecationandchildbirth,andmakesitpossibletocoughbybuildinguppressureandthensuddenlyreleasingtheair.)

Figure6-6.a&b.Coronalviewoflarynxshowinginletandoutletvalves(ventricularbandsandvocalfolds);c.Thevocalfoldsdonotopposetheoutflowofairandvibratetoproducesound.

The lower folds turnedupward, acting as an intakevalve that prevented airfromcomingintothelungs(Fig.6-6b).Thismade itpossible,byexpellingairfrom the lungs and contracting these lower folds, to create a vacuum thatpreventedtheribsfromrisingevenwhentheywerepulledupon,creatingfixedpointsforthearmmusclestoactupon.Thevocalfoldsnowfunctionedasdualvalvesforpreventingairfromcomingintoandflowingoutofthelungs,actingasaregulatorofintrathoracicpressure.

The evolutionof thesedual folds in the thyroarytenoidmusclewas amajordevelopmentinthelarynxasasound-producingorgan.Theupperfolds—calledtheventricularbandsorfalsevocalcordsbecausetheydonotcontributetotheproduction of sound—now functioned nicely as an exit valve for raisingintrathoracic pressure. In contrast, the lower folds—called the vocal foldsbecause they vibrate to produce sound—prevented the entrance of air into thelungs but did not oppose the outflowof air,whichmade thememinentlywellsuited to vibrate freely and to bemore finely controlled to produce a greaterrangeofpitches, volume, anddifferent thicknesses, or registers (Fig.6-6c). Inmonkeysandotherprimates,thesefoldshadrathersharpedges,givingthevoiceastrident tone;whenhominidsbegantowalkupright, thevocalfoldsacquiredmoreroundededgesandbecameevenbettersuitedtotheproductionofsound.

ThePharynx,UprightPosture,andHumanSpeech

Twofinaldevelopmentsthatmustbementionedinthedevelopmentofthevoicearetheevolutionofthearticulatorsandthehumanpharynx.We’vealreadyseenthat animals that chew food must have a separate passageway for food andbreathing.Theymustalsohavecheeksforholdingthefoodbetweentheteeth,aswell as verymovable tongues and lips. Being able tomake thesemovementswithina largeoralandpharyngealcavitymakes itpossible to forma rangeofvowelsaswellastoproducethebroken-upsoundsofhumanspeech,sincethetongue, palate, lips, and even the larynx itself are more free for articulation.Whenanimalsbecamearboreal,visionstartedtotakeoverfromolfactionastheprimary means of identifying predators; because air no longer needed to bedirectedthroughthenose,theepiglottisbecamedecoupledfromthepalate.Thisfreedtheseorgansforevenmoreefficientphonationandarticulation.

Thedevelopmentofanelongatedpharynxisanotheressentialdesignfeatureinthevocalsystem.Mostmammalscanaltertheshapeoftheoralcavityandlips(as inanimals thatbarkoryelp)butnot thatof thepharynx.Even inapes, thehyoidboneandlarynxlieclosetothemouth,sothatthepharynxistooshortforefficiently producing speech or sustained sounds (Fig. 6-7a). In humans,however,thesnoutdisappearsandisreplacedwiththenose,andthetongueliesfartherdownthegullet.Since thehyoidboneand larynxareat thebaseof thetongue,theyalsomovetoalowerposition,givinghumansalongerpharynxthanthatofapes.Assumingafullyuprightpostureopenedthewayforthehyoidboneandlarynxtodropstillfarther,creatinganevenlongerpharynx.Thisdescentof

the larynx inhumanscreatesa fully functionalpharynx for resonance, speech,andsustainedsound(Fig.6-7b).Westill raise the larynx toprotect theairwayduringswallowing,butitslowerpositionisacrucialcomponentofthesingingandspeakingvoice.

Figure6-7.Pharynxasresonatorin:a.Apes;b.Man.

TEpilogue

he human voice is one of nature’s greatest marvels. As we’ve seen, thevocalinstrumentismadeupofmultiplesystems,includingtherespiratory

system,thelarynx,thethroat,thevocaltract,andthefaceandjaw.

Althoughthelarynxis theprimarysound-producingorgan,wewouldnotbeable tomake soundwithout the flowofair from the lungs,whichprovides thepowersourcethatsetsthevocalcordsintomotion.

Thesecondcomponentofthevoiceisthelarynx,whichincludesthehousingforthevocalcordsandthevocalcordsthemselves.Itisherethatweareabletobringthevocalfoldstogetherandapart,tostretchthem,andtotenseortightenthem.Theseactionsareproducedby the intrinsicmusclesof the larynx,whicharerathercomplexbutbegin tomakesensewhenwe lookatwhatactionsareperformedandhowthedifferentmusclesproducethem.

Thelarynxitselfissuspendedwithinanetworkofmuscles—sometimescalledtheextrinsicmusclesofthelarynx—thatmovethelarynxwhenweswallowandalsohelpittocloseup.Whenwevocalize,thesemusclesactuponthelarynxtoassistthevocalfoldsinstretching,andalsoaidintheshapingofthevocaltract.

The fourth basic system is the vocal tract, which forms a resonator thataugments the soundcoming from the vibratingvocal cords.Because the vocaltract is not fixed in shape but can be altered by how we use the differentstructures such as the mouth, tongue, larynx, and palate, understanding itsanatomyiscrucialforvoiceusers.

Thefinalsystemisthefaceandjaw,whichplayacrucialroleinplacingthevoiceandinfluencethefunctioningofthethroatandlarynx.

Our breathing, the valve of the larynx, the suspensory musculature of thethroat, the vocal tract, the lips, face, and tongue—all these structures form aremarkable systemwhose sensitivity and control are hard to fathom.Workingtogether, these systems cooperate to produce one of nature’s greatestmarvels,thehumanvoice.

Index

Abdominalmuscles,14–15Adam’sapple,27Alveoli,22Aorta,10Aryepiglotticfolds,28Aryepiglotticmuscle,31,32Arytenoidcartilages,26,27,29

Breathing.SeealsoLungsauxiliarymusclesof,16definitionof,1diaphragmasmainmuscleof,10,12–13epiglottisand,90–91functionsof,1ribmovementand,1–2,6–9,17tongueduring,63

Buccinator,61

CartilagesofSantorini.SeeCorniculatecartilagesCartilagesofWrisberg.SeeCuneiformcartilagesCheeks,musclesof,80–81Chestregister,43Compressornariumminormuscle,76,77Conuselasticus,30,31Corniculatecartilages,27,28Coronoidprocess,82Corrugatorsuperciliimuscle,78,79Costalarch,3Costovertebraljoints,4,5Covering,71Cricoarytenoidjoint,28Cricoidcartilage,26,27,28,29,31Cricopharyngeusmuscle,48,49,50,53,61,62Cricothyroidmembrane,26,30Cricothyroidmuscle,34,40,42,50,51,52,53

Cuneiformcartilages,26,27,28

Deglutition.SeeSwallowingDepressoranguliorismuscle,81Depressorlabiiinferiorismuscle,81Depressorseptinasimuscle,76,77Diaphragmabdominalcavityand,13actionof,12anatomyof,10–11breathingand,10etymologyof,4,10movementof,2aspartition,4

Digastricmuscle,56,57,85Dilatatornarisposteriormuscle,76,77

Epiglottis,26,27,28,30,32–33,90–91Esophagus,22,23Externalabdominalobliquemuscle,14,15Eyes,musclesof,78–79

Face,musclesof,73Falsecords.SeeVentricularbandsFalsettoactionoflarynxmusclesin,44supported,53

Forehead,musclesof,78–79Frontalismuscle,78,79

Genioglossusmuscle,68,69Geniohyoidmuscle,50,51,54,56,57,85Glottis,35,38,39,42

Headvoice,45,53Heart,4,10,11Hyoglossusmuscle,50,51,57,68,69Hyoidboneanatomyof,54

functionsof,55locationof,54musclesof,56–58

Inferiorpharyngealconstrictormuscle,61,62Inferiorthyroarytenoids,30Intercostalmuscles,7–9,14,17,18Internalabdominalobliquemuscle,15

Jawdiaphragmof,85musclesof,56–58,84–85positionof,insinging,83sectionsof,82temporomandibularjointand,82–83

Jointcapsule,26

Laryngealpouch,31Laryngopharynx,60Larynxevolutionof,88,95extrinsicmusclesof,47–48,88falseelevatorsof,57frameworkof,26–28functionsof,25interiorof,30–31intrinsicmusclesof,34–45jointsof,28–29low,71originof,87structureof,25,26

Lateralcricoarytenoidmuscle,36,38Lateralpterygoidmuscle,84Latissimusdorsimuscle,21Levatoranguliorismuscle,80,81Levatorcostaemuscle,8Levatorescostarumbrevismuscle,8Levatorescostarumlongusmuscle,8Levatorlabiisuperiorisalaequenasimuscle,76,77Levatorlabiisuperiorismuscle,80,81Levatorscapulaemuscle,20

Levatorvelipalatinimuscle,66,67Lineaalba,14,15Lungsanatomyof,22capacityof,24diagramof,23locationof,4,22

Mask,74Massetermuscle,84Mastoidprocess,49Medialpterygoidmuscle,84Mentalismuscle,81Middlepharyngealconstrictormuscle,61,62Mouthfunctionsof,59musclesof,61–62,80–81

Muscularprocess,27Mylohyoidmuscle,56,57,85

Nasalcavity,75Nasalismuscle,76,77Nasopharynx,60,75Nose,musclesof,76–77Nostrils,75–77

Obliquearytenoidmuscle,36,39Omohyoidmuscle,50,53,58Orbicularisoculimuscle,78Orbicularisorismuscle,61,81Oropharynx,60

Palatearchingof,66–67evolutionand,90–91functionof,63musclesof,64–65sectionsof,63

Palatoglossusmuscle,64,65,68,69Palatopharyngeusmuscle,49,64,65,66

Passavant’scushion,63Pericardium,10,11Pharyngealtubercle,61,62Pharynxevolutionof,94–95functionsof,59lengthof,60musclesof,61–62sectionsof,60widened,71

Piriformsinus,28Pleuralcavity,22Posteriorcricoarytenoidmuscle,36,37,42Posturalmuscles,17Procerusmuscle,78,79Pterygomandibularraphe,61Pyramidalisnasimuscle,78Pyramidcartilages.SeeArytenoidcartilages

Quadratuslumborummuscle,8

Rectusabdominismuscle,14,15,18Rhomboidmajormuscle,20Rhomboidminormuscle,20Ribsfalse,3floating,2,3,5jointsof,4–5movementof,2,6,13,17sizeof,5true,3

Risoriusmuscle,81

Sacculuslaryngis,31Sacrospinalismuscles,17Salpingopharyngeusmuscle,64,65Scalenemuscles,16Scapulae,20Serratusposteriorinferiormuscle,19Serratusposteriorsuperiormuscle,19Singing

archedpalateand,66expiratorymusclesand,13jaw’spositionduring,83suspensorymusclesofthelarynxduring,47,51–53,71tongue’spositionduring,69–71

Spinesupportof,17vertebraeof,3

Sternocleidomastoidmuscle,16,18Sternohyoidmuscle,50,52,53,54,58Sternothyroidmuscle,48,49,50,52,53,58“Strap”muscles,58Styloglossusmuscle,56,57,68,69Stylohyoidmuscle,50,51,54,55Styloidprocesses,48,49,55Stylopharyngeusmuscle,48,49,50,52,53,71Superiorpharyngealconstrictormuscle,61,62Superiorthyroarytenoids,30,31Swallowing,47,62,63,66,88Swimming,63

Temporalismuscle,84Temporomandibularjoint,82–83Tensorvelipalatinimuscle,66Thyroarytenoidmuscle,30,31,35,41,42,92Thyroepiglotticmuscle,31,33Thyrohyoidligament,48Thyrohyoidmembrane,26Thyrohyoidmuscle,48,49,50,51,53,58Thyroidcartilage,26,27,28,29,31Tidalflow,24Tongueanatomyof,68–69falseelevatorsof,57functionsof,68–69positionof,insinging,69–71

Tonguebone.SeeHyoidboneTrachea,22,23,31Transversearytenoidmuscle,36,39Transversusabdominis(transversalis)muscle,15Transversusthoracismuscle,9,14Trapeziusmuscle,21

Triticeacartilages,26

Uvula,64,65,66

Velum,63Ventricularbands,30,31,92,93Vertebrae,3Vocalcords.SeeVocalfoldsVocalfoldsinchestvoice,43designof,92–93infalsetto,46lengtheningandshorteningof,37,40–42locationof,31openingandclosingof,25,26,37–39structureof,34waveactionof,42

Vocalismuscle,30–31,35,41Vocalligaments,26Vocalprocesses,27Vocalproduction,fivesystemsresponsiblefor,xii,97Vocaltract,59,97

Zygomaticusmajormuscle,80,81Zygomaticusminormuscle,80,81

ABOUTTHEAUTHOR

DR.THEODOREDIMONisthefounderanddirectorofTheDimonInstituteandanadjunctprofessoratTeachersCollege,ColumbiaUniversity.Hereceivedbothmaster’sanddoctoratedegreesineducationfromHarvardUniversityandisan internationally renowned teacher of mind/body disciplines. He has writtensevenbooks,includingAnatomyoftheMovingBody;TheBodyinMotion;YourBody,YourVoice;TheElementsofSkill;TheUndividedSelf;ANewModel ofMan’sConsciousDevelopment;andNeurodynamics:TheArtofMindfulness inAction.

ABOUTTHEILLUSTRATORG. DAVID BROWN has been the illustration program director at WinthropUniversity in South Carolina since 2005. Prior to that he was a medicalillustrator for twenty-five years in Dallas, Texas. He completed his medicalillustrationgraduatestudiesattheUniversityofTexasHealthScienceCenteratDallas and his undergraduate studies in Visual and Environmental Studies atHarvard.ThisisthefifthbookthathehasillustratedwithTedDimon.

ALSOBYTEDDIMONavailablefromNorthAtlanticBooks

Neurodynamics978-1-58394-979-5

YourBody,YourVoice978-1-58394-320-5

TheBodyinMotion978-1-55643-970-4

AnatomyoftheMovingBody,SecondEdition978-1-58394-687-9

TheElementsofSkill978-1-55643-476-1

NorthAtlanticBookswww.northatlanticbooks.com

NorthAtlanticBooksisanindependent,nonprofitpublishercommittedtoaboldexplorationoftherelationshipsbetweenmind,body,spirit,andnature.

AboutNorthAtlanticBooks

NorthAtlanticBooks(NAB) isan independent,nonprofitpublishercommittedtoaboldexplorationoftherelationshipsbetweenmind,body,spirit,andnature.Founded in 1974, NAB aims to nurture a holistic view of the arts, sciences,humanities,andhealing.Tomakeadonationortolearnmoreaboutourbooks,authors,events,andnewsletter,pleasevisitwww.northatlanticbooks.com.

NorthAtlanticBooks is the publishing armof theSociety for theStudy ofNativeArts andSciences, a501(c)(3) nonprofit educational organization that promotes cross-cultural perspectives linking scientific,social,andartisticfields.Tolearnhowyoucansupportus,pleasevisitourwebsite.