THEPELVIS

BONYPELVISJOINTSANDLIGAMENTSWALLSANDFLOOROFPELVISPERINEUM

THEBONYPELVIS

Thepelviccavityistheinferiormostpartoftheabdominopelviccavity.Thepelvisissubdividedintogreaterandlesserpelves.Thegreaterpelvisissurroundedbythesuperiorpelvicgirdle.Thelesserpelvisissurroundedbytheinferiorpelvicgirdle.

Thepelvicgirdleconnectsthelowerlimbtotheaxialskeletonviathesacroiliacjoint,asynovialjointinwhichmobilityhasbeensacrificedforstabilityandstrength,toallowforeffecJveweighttransmissionfromthetrunktothelowerlimb.

Anteriorly,thepelvicgirdlearJculateswiththecontralateralgirdleatthepubicsymphysis.

THEBONYPELVIS

Rightandle=hipbonesdevelopfromthefusionofthreebones:•  ilium•  ischium•  pubis

Sacrumisformedbythefusionoffivesacralvertebrae.

THEPELVICGIRDLE:•  aMachesthefreelowerlimbtotheaxialskeleton•  bonyringcomposedofthesacrumandrightandleNhipbones,

jointedanteriorlyatthepubicsymphysis

THEHIPBONEisformedbyfusionofthe:•  ILIUM•  ISCHIUM•  PUBIS

THEHIPBONEAtbirth,thethreebonesarejoinedbyhyalinecarJlage.Thebonesbegintofusebetween15-17yearsofage.

RELATIONSHIPTOOTHERREGIONSthereare4majorentryandexitpointsbetweenthelowerlimbandtheabdomen,pelvis,andperineumTheseare:•  thegapbetweentheinguinalligamentandpelvicbone,•  thegreatersciaJcforamen,•  theobturatorcanal(atthetopoftheobturatorforamen),and•  thelessersciaJcforamen.

THEHIPBONE:THEILIUM

•  Bodyfusedtoischiumandpubis,allmeeJngintheacetabulum(socketforarJculaJonwithfemoralhead)

•  Alaofilium(wing):weakspotofilium!•  ASISandPSIS

THEBONYPELVIS

THEHIPBONE:THEILIUM

NeurovascularstructuresfromwithinthepelvicgirdlepassthroughthegreaterandlessersciaKcforamentotheglutealregion

THEHIPBONE:THEPUBIS

•  Bodyfusedwithothertwobones•  Ramusfusedwithischium •  Medially,thesymphysialsurfacearJculateswithcontralateralpubisbymeansofthepubicsymphysis

THEHIPBONE:THEISCHIUM

•  Bodyfusedwithothertwobones•  Ramusfusedwithpubis •  Thebody’sweightrestsonthelargeischialtuberositywhensiYng(‘siYngbone’)–itprovidesaMachmentofposteriorthighmuscles

THEBONYPELVIS

THEOBTURATORFORAMENTheobturatorforamenliesbelowandslightlyanteriortotheacetabulum,betweenthepubisandischium.Theforamenisalmostclosedbytheobturatormembrane,whichisaMachedtoitsmargins,exceptsuperolaterally,whereacommunicaJonremainsbetweenthepelvisandthigh.

THEOBTURATORFORAMEN•  largeopeninginthehipbone•  it’sboundedby:ramiofthepubisandischium•  isinferiortotheacetabulum•  mostofitisclosedbyamembraneofflatconnecJveJssue,theobturatormembrane

THEBONYPELVIS

THEACETABULUM•  acup-shapeddepressionwheretheheadofthefemurarJculateswiththepelvicgirdle

•  allthreeprimarybonescontributetotheformaJonoftheacetabulum

Thepubicarchisformedbytheischiopubicrami(inferiorramiofthepubisandischium)ofthetwosides.Theseramimeetatthepubicsymphysis,theirinferiorbordersdefiningthesubpubicangle

PELVICINLET(UPPERPELVICAPERTURE,PELVICBRIM)Itdividesthepelvisinto:•  greater(false)and•  lesser(true)pelves

THEBONYPELVIS

PELVICINLET(UPPERPELVICAPERTURE,PELVICBRIM)Thepelvicbrimisformedbythe:•  promontoryandalaofthesacrum•  arcuatelineontheinnersurfaceoftheilium•  pectenpubis(pecJnealline)•  pubiccrest

Thepelvicoutlet(inferiorpelvicaperture)isboundedbythe:•Pubicarchanteriorly•IschialtuberosiJeslaterally•Inferiormarginofthesacrotuberousligament(runningbetweenthecoccyxandtheischialtuberosity)posterolaterally•Tipofthecoccyxposteriorly

THEBONYPELVIS

Thegreaterpelvis(falsepelvis)isthepartofthepelvis:•Superiortothepelvicinlet•BoundedbytheiliacalaeposterolaterallyandtheanterosuperioraspectoftheS1vertebraposteriorly•Occupiedbyabdominalviscera(e.g.,theileumandsigmoidcolon)

Thelesserpelvis(truepelvis)isthepartofthepelvis:•Betweenthepelvicinletandthepelvicoutlet•Boundedbythepelvicsurfacesofthehipbones,sacrum,andcoccyx•Thatincludesthetruepelviccavityandthedeeppartsoftheperineum,specificallytheischio-analfossae•Thatisofmajorobstetricalandgynecologicalsignificance.

THEBONYPELVIS

PELVICDIAMETERS(CONJUGATES)ThediametersofthelesserpelvisarenotedradiographicallyormanuallyduringapelvicexaminaJon.

PELVICDIAMETERS(CONJUGATES)Thetrue(obstetrical)conjugatefromthemiddleofthesacralpromontorytotheposterosuperiormargin(closestpoint)ofthepubicsymphysis.

THEPELVIS

>11cm

PELVICDIAMETERS(CONJUGATES)ThediagonalconjugateismeasuredbypalpaJngthesacralpromontorywiththeJpofthemiddlefinger,usingtheotherhandtomarktheleveloftheinferiormarginofthepubicsymphysisontheexamininghand.

12cm

PELVICDIAMETERS(CONJUGATES)Theinterspinousdistance(betweenischialspines)isnormallythenarrowestpartofthepelviccanal(thepassagewaythroughthepelvicinlet,lesserpelvis,andpelvicoutlet)throughwhichababy’sheadmustpassatbirth.

THEPELVIS

10cm

Theprimaryjointsofthepelvicgirdlearethe:•  pubicsymphysis•  sacro-iliacjoints•  lumbosacraljoints•  sacrococcygealjoint

THEJOINTS

THEPUBICSYMPHYSISThepubicbonesmeetinthemidlineatthepubicsymphysis,asecondarycarJlaginousjoint

THEPUBICSYMPHYSISPosteriorlytheupperpartofthejointisseparatedfromtheinferolateralsurfacesofthebladderbythepotenJalretropubicspace(ofRetzius).

THESACRO-ILIACJOINTThesacro-iliacjointisasynovialarJculaJonbetweenthesacralandiliacauricularsurfaces.

THEJOINTS

Weightistransferredfromtheaxialskeletontotheiliaviathesacro-iliacligaments:•  anteriorsacro-iliac•  interosseoussacro-iliac•  posteriorsacro-iliac,•  iliolumbar,•  sacrotuberous•  sacrospinus

THEJOINTSTHELUMBOSACRALJOINTSL5andS1vertebraearJculateattheanteriorintervertebraljointformedbytheL5/S1IVdiscbetweentheirbodiesandattwoposteriorzygapophysialjointsbetweenthearJcularprocessesofthesevertebrae.ThesacrococcygealjointisasecondarycarJlaginousjointwithanIVdisc.

THEMUSCLESOFTHEPELVISPiriformisandobturatorinternus,althoughformingpartofthewallsofthepelvis,areconsideredasprimarilymusclesofthelowerlimb.Piriformisformspartoftheposterolateralwallofthetruepelvis.PiriformispassesoutofthepelvisthroughthegreatersciaJcforamen.

THEWALLSOFPELVIS

THEOBTURATORINTERNUSObturatorinternusandthefasciaoveritsupperinner(pelvic)surfaceformpartoftheanterolateralwallofthetruepelvis.

THEMUSCLESOFTHEPELVISLevatoraniandcoccygeusformthepelvicdiaphragmanddelineatethelowerlimitofthetruepelvis.

THELEVATORANImusclesarethe:•  puborectalis•  pubococcygeus•  iliococcygeus.

THEWALLSOFPELVIS

THELEVATORANIThepuborectalis:formsaU-shapedmuscularsling(puborectalsling),boundingtheurogenitalhiatus.ThispartplaysamajorroleinmaintainingfecalconJnence.Thepubococcygeus:thewiderbutthinnerintermediatepartofthelevatoraniTheIliococcygeus:theposterolateralpartofthelevatorani

THELEVATORANIItistonicallycontractedmostoftheJmetosupporttheabdominopelvicviscera,andtoassistinmaintainingurinaryandfecalconJnence.ThelevatoranimustrelaxtoallowurinaJonanddefecaJon.Theincreasedintra-abdominalpressurefordefecaJonisprovidedbycontracJonofthe(thoracic)diaphragmandmusclesoftheanterolateralabdominalwall.ThefasciaeinvesJngthemusclesareconJnuouswithvisceralpelvicfasciaabove,perinealfasciabelowandobturatorfascialaterally.

THEWALLSOFPELVIS

THEANTERO-INFERIORPELVICWALLTheantero-inferiorpelvicwallisformedprimarilybythebodiesandramiofthepubicbonesandthepubicsymphysis.

THEWALLSOFPELVIS

THELATERALPELVICWALLSThelateralpelvicwallsareformedbytherightandleNhipbones,eachofwhichincludesanobturatorforamenclosedbyanobturatormembrane.

THEPOSTERIORPELVICWALLSTheposteriorpelvicwallconsistsofabonywall(thesacrumandcoccyx)andmusculoligamentousposterolateralwalls,formedbytheligamentsassociatedwiththesacro-iliacjointsandpiriformismuscles

THEPELVICFLOORThepelvicfloorisformedbythefunnel-shapedpelvicdiaphragmThepelvicdiaphragmconsistsofthecoccygeusandlevatoranimusclesandthefasciascoveringthesuperiorandinferioraspectsofthesemuscles.Thepelvicdiaphragmlieswithinthelesserpelvis,separaJngthepelviccavityfromtheperineum,forwhichitformstheroof.

THEWALLSOFPELVIS

THEPELVICFLOORThemusclesofthepelvicdiaphragm:•  thecoccygeusmusclesarisefromthelateralaspectsoftheinferior

sacrumandcoccyx,•  thelevatoraniisthelargerandmoreimportantpartofthepelvic

floor.Ananteriorgapbetweenthemedialbordersofthelevatoranimusclesofeachside(theurogenitalhiatus)givespassagetotheurethraand,infemales,thevagina

THEPERINEUMTheperineumisanapproximatelydiamond-shapedregionwhichliesbelowthepelvicfloor,betweentheinneraspectsofthethighsandanteriortothesacrumandcoccyx.

THEPERINEUM

THEPERINEUMTheperineumisboundedanteriorlybythepubicsymphysisanditsarcuateligament,posteriorlybythecoccyx,anterolaterallybytheischiopubicramiandlaterallybytheischialtuberosiJes,andposterolaterallybythesacrotuberousligaments.

THEPERINEUMThedeeplimitoftheperineumistheinferiorsurfaceofthepelvicdiaphragmanditssuperficiallimitistheskinwhichisconJnuouswiththatoverthemedialaspectofthethighsandthelowerabdominalwall.

THEPERINEUMAnarbitrarylinejoiningtheischialtuberosiJes(theinterischialline)dividestheperineumintoananteriorurogenitaltriangleandaposterioranaltriangle.Theurogenitaltrianglefacesdownwardsandforwards,whereastheanaltrianglefacesdownwardsandbackwards.ThemaleurogenitaltrianglecontainsthebulbandaMachmentsofthepenis.Thefemaleurogenitaltrianglecontainsthemonspubis,thelabiamajora,thelabiaminora,theclitorisandthevaginalandurethralorifices

THEPERINEUM

PERITONEUMTheparietalperitoneumoftheposteriorsurfaceoftheanteriorabdominalwallandthatliningtheposteriorabdominalwallconJnueintothepelvisasthepelvicperitoneum.

THEPERINEUM

PERITONEUMOFTHEMALEPELVISTheperitoneumoftheleNlowerabdominalwallisreflectedfromthejuncJonofthesigmoidcolonandanterolateralsurfaceoftherectumtolinethebrimandupperinnersurfaceofthetruepelvis.

Theperitoneumisreflectedanteriorlyfromtheanteriorsurfaceoftherectumovertheupperpolesoftheseminalvesiclesandontotheposteriorsurfaceofthebladder,producingtherectovesicalpouch.Theperitoneumcoversthesuperiorsurfaceofthebladder,andformsaparavesicalfossaoneachsidelimitedlaterallybyaridgeofperitoneumwhichcontainstheductusdeferens.

PERITONEUMOFTHEFEMALEPELVISInfemalestheperitoneumcoverstheupperrectumasitdoesinthemale,butitdescendsfurtherovertheanteriorsurfaceoftherectum.Therectovesicalpouchisoccupiedbytheuterusandvagina.Theperitoneumfromtherectumisreflectedanteriorlyontotheposteriorsurfaceoftheposteriorfornixofthevaginaandtheuterus,producingtherecto-uterinepouch(ofDouglas).

THEPERINEUM

PERITONEUMOFTHEFEMALEPELVISOnlytheuterinetubes(exceptfortheirosJa,whichareopen)areintraperitonealandsuspendedbyamesentery.Theovaries,althoughsuspendedintheperitonealcavitybyamesentery,areNOTcoveredwithglisteningperitoneum.

PERITONEUMOFTHEFEMALEPELVISTheperitoneumcoversthefundusoftheuterustoitsanterior(vesical)surfaceasfarasthejuncJonofthebodyandcervix,fromwhichitisreflectedforwardstotheuppersurfaceofthebladder,formingashallowvesico-uterinepouch.Peritoneumisreflectedfromthebladdertotheposteriorsurfaceoftheanteriorabdominalwallasitisinmales.

THEPERINEUM

PELVICFASCIAThepelvicfasciaisconnecJveJssuethatoccupiesthespacebetweenthemembranousperitoneumandthemuscularpelvicwallsandfloorNOToccupiedbythepelvicviscera.Thepelvicfasciaemaybeconvenientlydividedintotheparietalpelvicfascia,whichmainlyformsthecoveringsofthepelvicmuscles,andthevisceralpelvicfascia,whichformsthecoveringsofthepelvicvisceraandtheirvesselsandnerves.

THEPELVICFASCIA

THEPARIETALPELVICFASCIATheparietalpelvicfasciaconsistsofthe:•  obturatorfascia•  fasciaeoverpiriformis,•  overlevatorani(thepelvicdiaphragm),•  presacralfascia.

THEPELVICFASCIA

THEVISCERALPELVICFASCIAThevisceralpelvicfasciaisformedfromcondensaJonsofconnecJveJssuewhicharecloselyassociatedwiththepelvicvisceratowhichitrelatesandwiththeneurovascularstructuressupplyingorrunningnearthoseorgans.

THEPELVICFASCIAThepotenJalspaces,normallyconsisJngonlyofalayerofloosefaMyJssue,aretheretropubic(orprevesical,extendedposterolaterallyasparavesical)andretrorectal(orpresacral)spaces,respecJvely.ThepresenceoflooseconnecJveJssuehereaccommodatestheexpansionoftheurinarybladderandrectalampullaastheyfill.

THEPELVICFASCIA

THEDEEPPERINEALPOUCHThedeepperinealpouch(space)isboundedinferiorlybytheperinealmembrane,superiorlybytheinferiorfasciaofthepelvicdiaphragm,andlaterallybytheinferiorporJonoftheobturatorfascia(coveringtheobturatorinternusmuscle)

THEDEEPPERINEALPOUCHInbothsexes,thedeepperinealpouchcontains:•  Partoftheurethra,centrally.•  Theinferiorpartoftheexternalurethralsphinctermuscle,•  Anteriorextensionsoftheischio-analfatpads.

THEPELVICFASCIA

THEDEEPPERINEALPOUCHInmales,thedeepperinealpouchcontainsthe:•  narrowestpartofthemaleurethra•  deeptransverseperinealmuscles•  bulbo-urethralglands•  dorsalneurovascularstructuresofthepenis.

THEDEEPPERINEALPOUCHInfemales,thedeepperinealpouchcontainsthe:•  proximalpartoftheurethra•  amassofsmoothmuscleassociatedwiththeperinealbody•  dorsalneurovasculatureoftheclitoris.