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Download ANAT30008 LECTURE NOTES PART 2 Lecture 18 – Bones and
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ANAT30008LECTURENOTESPART2 Lecture18–Bonesandjointsofpelvis • Thisistheintactbonypelvisanditiscomprisedofapairofhipbones togetherwiththesacrumandcoccyxposteriorly Sacroiliac joint • Thereisasynovialsacroiliacjointlaterally • Anteromedially,thereisisasecondarycartilaginousjointcalledthepubic Sacrum Hip bone and coccyx symphysis Pubic symphysis The hip bone is made up of 3 fused bones: ischium, il • Thehipboneismadeupof3fusedbones:ischium,iliumandpubis • Theacetabulumandtheobturatorforamenareformedbythe3fused bones acetabulum obturator foramen Ilium • Thisismadeupoftheiliaccrestsuperiorly andthisextendsbetweentheASISand theposteriorsuperioriliacspine • Therearealso3surfaces o Glutealsurfacegivesrisetothe glutealmuscles o Iliacfossawhichgivesriseto iliacus o Sacralsurfacewhichincludesthe articularsurfaceforthesacroiliac joint Pubis • Thepubicboneismadeupofthepubic bodywiththepubiccrestontopand2 rami–superiorpubicramusandinferiorpubicramus • Thebodyofeachpubicbonearticulatesatthemidlineatthepubicsymphysis Drake R L, Vogl W, Mitchell A W M. Gray’s Anatomy For Students. Churchill Livingstone; 2nd ed. 2010. ISBN 9780808924067. p.424 f • Thesuperiorsurfacethatisthepubiccrestiscontinuouswiththepubictubercle.Thissurfaceisalso continuouswiththepectinealline(lacunarligamentpansinwardfromthemedialpartoftheinguinal ligamentthatwenttothepectineallineofthepubis) Ischium • Thisismadeupofabodyandsingleramus • 2bonyfeaturesoftheischium o Theischialtuberosity–thisgivesattachmentstothehamstringsgroup o IschialSpine–thisseparatesthegreatersciaticnotchabovefromthelessersciaticnotchbelow • Acetabulumformsthesocketfthehipjointandthisisformedbytheunionofischium o Duringdevelopmentwehaveatri-radiatecartilageinsertedhereseparatingthe3bones*but ultimatelytheyfuse) • Obturatorforamen–thisispartofthewallofthepelvis o Thisisalargeopeningboundedbytheramiofthepubisandtheramusoftheischium Netter, F.H. Interactive Atlas of Human Anatomy. 3rd ed. New Jersey, Icon Learning Systems, 2003, ISBN: 1-929007-15-9, Plate # Drake R L, Vogl W, Mitchell A W M. Gray’s Anatomy For Students. Churchill Livingstone; 2nd ed. 2010. IS Sacrum Sacrum • Thisisatriangularbonemadeupof5fused ala ala promontory vertebraeandtheyareoriginaltransverse processes. SIJ 1 LSJ o Originaltransverseprocessesfusetogether lateral lateral 2 mass mass toformalateralmassandthesuperior surfaceofthelateralmassiscalledthe 3 sacralala SCJ 4 o Sacralala=thetopofthefusedtransverse processesofthesacralvertebraethatcome 5 together Pelvis (from Latin) = basi c • TheSuperiorsurfacealsohasamidlineprominence calledthesacralpromontory.Thesacralalasitson Divided into ‘false’ eithersideofthis (greater) & ‘true’ (lesse Pelvis (from Latin) = basin • Sacrumarticulatesabovewiththelumbar-sacraljointabove,belowwiththecoccyxviathesacrococcygeal pelvis jointandlaterallywiththeileumoneithersideofthesacroiliacjoint Divided into ‘false’ (greater) & ‘true’ (lesser) • Iliaccrestandiliacfosseprojectupof pelvis thepelvicbrim • Everythingabovethepelvicbrimis calledthefalsepelvisorgreaterpelvis (includingiliaccrestandiliacfosse) • Everythingbelowthepelvicbrimis calledthetruepelvisorlesserpelvis • Thelinedelineatingthefalsepelvisfrom thetruepelvisistheiliopectinealline. Thisisbasicallythecontinuationofthe pectineallineofthepubis Iliopectineal line • Thisispartoftheposteriorabdominal demarcating false pelvis wallastheiliacusstartswithinhere Iliopectineal line above from true pelvis demarcating false pelvis • Thefalsepelvisisreallyconsideredpart below above from true pelvis oftheposteriorabdominalwallandit below formsaprotectionfortheabdominal Drake R L, Vogl W, Mitchell A W M. Gray’s Anatomy For Students. An@tomedia: Pelvis Systems viscera(andhasnothingtodowiththepelviccontents) Churchill Livingstone; 2nd ed. 2010. ISBN 9780808924067. p.429 An@tomedia: Pelvis Systems fig. 5.28 • Thetruepelvis(includingthesacrumandthecoccyx)sitsbetweenthepelvicinletandpelvicoutlet • Tracingalongthepelvicbrim: o Pelvicinletisboundedbythepubiccrestanteriorly.Thenitfollowsthepectineallineofthepubis. Thereisanarchofthepelvicinletcalledthearcuatelineoftheilium.Thenwegettosacralalaand intothesacralpromontory Pelvictypes(basedonshapeofinlet) • Theydifferinshapes • Females–pelvicinletisovalinshapeandwidertransversely–thisisthewidest transversediameterofthepelviscavity–importantforchildbirth ~50% Pelvic types o Gynaecoid–classicfemalepelvicinlet (based on • Male shape of o typicalpelvictypeisandroid inlet) ~20% o anthropoidisalsoacommonvariant • Therearealsootherwaysthatmaleandfemalepelviscandiffer[diagram] Netter, F.H. Interactive Atlas of Human Anatomy. 3rd ed. New Jersey, Icon Learning Systems, 2003, ISBN: 1-929007-15-9, Fig. 457B & 335 An@tomedia: Pelvis Systems male female general structure thick and heavy thin and light shape of inlet heart shaped transverse oval ~30% An@tomedia: Pelvis Systems greater sciatic notch narrow inverted v almost 90deg subpubic arch acute angle obtuse angle acetabulum large small obturator foramen round oval The width of the acetabulum when compared to the width of the pubic bone is a particularly reliable index of male and female differences. In the female ~2% • • Thereisvariationinthegeneralstructure,shapeofinlet,angulationofthegreatersciaticnotch,inthesubpubicarch,thesizeoftheacetabulumandthesizeoftheobturatorforamen Thewidthoftheacetabulumwhencomparedtothewidthofthepubicboneisaparticularlyreliableindex ofmaleandfemaledifferences.Inthefemale,thedistancefromacetabulumtopubicsymphysisisgreater Pelvic inlet/outlet thanthewidthoftheacetabulum.Inthemaleitisaboutthesame Pubicinlet/outlet • Pelvicoutletisdiamondshaped • Thisisdefinedasextendingfromthepubicsymphysis The plane of least dimensions anteriorlytothetipofthecoccyxposteriorly,andeither passes through the ischial spine, sidearetheischialtuberosity’s S4 & base of pubic bone • Therearevariationsindimensionbetweenmaleand malebutdiamondshapeisconserved The plane of least dimensions passes through the ischial spine, S4 & base of pubic bone Pelvic inlet, narrow pelvic plane & outlet An@tomedia: Pelvis Systems s ine, Pelvic inlet, narrow pelvic plane & outlet An@tomedia: Pelvis Systems Babiesneedtogointhroughtheinletandoutthroughtheoutlet An@tomedia: Pelvis Systems Planeofleastdimensionpassesthroughtheischialspine,S4andbaseofpubicbone(thisiswherethe Pelvicbabiesheadgoesthrough) inlet, narrow pelvic plane & outlet • Duringchildbirth,thebabiesheadrotatesconstantlyandflextopresentsitsnarrowestpartofthebody (whichisthehead)tothenarrowestopeningofthepelvis • • Jointsofthepelvis • Thejointsofthepelviscompriseofa pairofsynovialjointslaterally (sacroiliacjoints)andsecondary cartilaginousjointsinthemidline (pubicsymphysis) • Thesacroiliacjointisasynovialjoint o Articularsurfaceisanear shapedsurface/auricular surfaceoftheposteriorpart ofthealaofthesacrumand earshapedsurfaceofthe ilium • Mostimportantpartofthesacroiliac jointsarethesupportingstructures • Sacroiliacligamentsattachdirectly anteriorlybetweenthesacrumand Drake R L, Vogl W, Mitchell A W M. Gray’s Anatomy For Students. Churchill Livingstone; 2nd ed. 2010. ISBN 9780808924067. p.427 fig. 5.24 theilium–thisiscalledtheanteriorsacroiliacligament • Sacroiliacligamentsbehindarecalledposteriorsacroiliacligaments • Theseanteriorandposteriorsacroiliacligamentspassacrossthefrontoftheanteriorandposteriorpartsof thejointreinforcingthecapsule
