The ligament that limits hyperextension of the vertebral column is:

EXPERIMENT1DETERMINATIONOFDISSOLVEDOXYGENINWATERINTRODUCTIONThedissolvedoxygencontentisanimportantindexwhenconsideringitssuitabilityfortownsupply.Agoodcleanpotablewaterwillgivedissolvedoxygenvalueclosetothetheoreticalvalueforthesaturatedsolutionofoxygeninwater.Whenthereispollutionfromorganicmatterandothertradeeffluents,thedissolvedoxygenisupinvariousbiochemicaloxidationprocessesanditsisonlyslowlyreplacedthroughsurfaceabsorption.Suchwaterwillgivealowdissolvedoxygencontentuntiloxidationiscompleted.Adequatedissolvedoxygenisnecessaryforthelifeoffishandotheraquaticorganisms.ThemethodsdescribedbelowforthedeterminationofoxygeninwaterisbasedonthatdevisedbyWinkler.Whenmanganesehydroxideisprecipitatedinthewatersampleitisquicklyoxidizedtohigherhydratedoxides(probablyinthefourvalentstate)bythedissolveoxygen.Iodine,equivalenttothedissolvedoxygencontent,isthenliberatedonacidificationinthepresenceofiodine,anditmaybetitratedwithstandardthio‐sulphate.INTERFERENCESANDPRE–TREATMENTMostoxidisingandreducingsubstancese.gdissolvedorganicsubstances,nitriteions,higher‐valencymanganesecompounds,activechlorine,sulphideandsulphiteions,iron(II)andironsinterfere.Theinfluenceofthedissolvedorganicsubstancescanbeexcludedbyconversionofthemanganesehydroxidesintooxygen‐sensitivecarbonatesbysubsequentadditionof4cm3ammoniumhydrogencarbonatesolution.Nitriteinacidicsolutionscatalysestheliberationofiodideandcanbedecomposedbyadditionofalkaline‐iodide‐azidesolution.Iron(III)ionsarerenderedinactiveduringthedeterminationbytheadditionof4cm3phosphoricacidor2cm3potassiumfluoridesolution.EXPERIMENTALCollectionofsampleCollectthesampleinanarrownecked200‐300cm3glassbottlehavinganaccuratelyfittinggroundglassstopper.Ifthewaterfromatap,passthewaterdownaglasstubetothebottomofthebottleandallowwatertooverflowfor2‐3minutesbeforeinsertionofthestopper.Whensamplingstreamwater,displacethewaterinthebottleseveraltimes,beforecollectingthesample.The
watertemperature,weatherconditionsandnatureofthewatersampleatthetimeofsamplingshouldberecorded.Avoidinclusionofairbubblesinthesamplebottle.PROCEDUREfortheDeterminationofDissolvedOxygeninWaterCarefullyremovethestopperfromthesamplebottleandaddinturn1cm3manganoussulphatesolutionfollowedby1cm3alkaline‐iodide‐azidesolution.Whenintroducingvariousreagentsintothefullbottleofsample,thetipsofthepipettesshouldbewellbelowthesurfaceoftheliquid.Replacethestoppercarefullyaftereachadditionsoastoavoidinclusionofairbubbles.Thoroughlymixthecontentsbyinversionandrotationuntilaclearsupernatantwaterisobtained.Add1cm3concentratedsulphuricacidwiththetripofthepipettebelowthelevelofsolutionandagainreplacethestopper.Mixwellbyrotationuntiltheprecipitatehascompletelydissolved.Pipetteintoa250cm3conicalflask100cm3ofthesolutionandimmediatelytitrateitagainststandardsodiumthiosulphate(0.0125moldm‐3)usingfreshlypreparedstarchsolutionastheindicator(addwhensolutionbecomespaleyellow).Carryoutthetitrationinduplicate.StandardisationofSodiumThiosulphateMix5cm3ofpotassiumiodidesolution(10%w/v)and10cm3ofthedilutesulphuricacid(1:3v/v)andadd2cm3of0.025moldm‐3potassiumiodatesolutioninthatorderinaglass‐stopperedflask.Addabout100cm3ofdistilledwater.Titrateimmediatelywithsodiumthiosulphatesolutionuntilthecolourispaleyellow.Add2or3dropsofstarchsolution(freshlyprepared)andcontinuethetitrationuntilthebluecolourjustdisappears.REPORTExplainthereactioninvolvedinthedeterminationofdissolvedoxygeninwaterusingWinklermethods.Establishtherelationship:10cm3of0.0125moldm‐3sodiumthiosulphate=1mg02.Reporttheresultinmgdm‐3andaspercentagesaturation(refertothetableattached)REAGENTSManaganoussulphatesolutionDissolve100gmanaganoussulphate(MnSO4.4H2O)in200cm3distilledwater.Alkaline‐iodide‐azidesolutionDissolve100gsodiumhydroxidein100cm3distilledwater.Allowtostandforsomedays,duringwhichanycarbonatepresentsinkstothebottom.Siphonoffalloftheclearliquid,add30gpotassiumiodideand2gsodiumazideandmakeupto200cm3withdistilledwater.Storeinplasticcontainer.SodiumThiosulphate(0.0125moldm‐3)Dilute125cm30.1moldm‐3sodiumthiosulphateto1literwithdistilledwater.Potassiumiodidesolution(0.025moldm‐3)