anat30008 lecture notes part 2 lecture 18 – …drake r l, vogl w, mitchell a w m. gray’s anatomy...
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ANAT30008LECTURENOTESPART2Lecture18–Bonesandjointsofpelvis
• Thisistheintactbonypelvisanditiscomprisedofapairofhipbonestogetherwiththesacrumandcoccyxposteriorly
• Thereisasynovialsacroiliacjointlaterally• Anteromedially,thereisisasecondarycartilaginousjointcalledthepubic
symphysis
• Thehipboneismadeupof3fusedbones:ischium,iliumandpubis• Theacetabulumandtheobturatorforamenareformedbythe3fused
bonesIlium
• ThisismadeupoftheiliaccrestsuperiorlyandthisextendsbetweentheASISandtheposteriorsuperioriliacspine
• Therearealso3surfaceso Glutealsurfacegivesrisetothe
glutealmuscleso Iliacfossawhichgivesriseto
iliacuso Sacralsurfacewhichincludesthe
articularsurfaceforthesacroiliacjoint
Pubis
• Thepubicboneismadeupofthepubicbodywiththepubiccrestontopand2rami–superiorpubicramusandinferiorpubicramus
• Thebodyofeachpubicbonearticulatesatthemidlineatthepubicsymphysis• Thesuperiorsurfacethatisthepubiccrestiscontinuouswiththepubictubercle.Thissurfaceisalso
continuouswiththepectinealline(lacunarligamentpansinwardfromthemedialpartoftheinguinalligamentthatwenttothepectineallineofthepubis)
Ischium
• Thisismadeupofabodyandsingleramus• 2bonyfeaturesoftheischium
o Theischialtuberosity–thisgivesattachmentstothehamstringsgroupo IschialSpine–thisseparatesthegreatersciaticnotchabovefromthelessersciaticnotchbelow
• Acetabulumformsthesocketfthehipjointandthisisformedbytheunionofischiumo 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 # 335B
Hip bone Sacrum and coccyx
Sacroiliac joint
Pubic symphysis The hip bone is made up of 3 fused bones: ischium, ilium and pubis
acetabulum
obturator foramen
Drake R L, Vogl W, Mitchell A W M. Gray’s Anatomy For Students. Churchill Livingstone; 2nd ed. 2010. ISBN 9780808924067. p.423 fig. 5.20
Drake R L, Vogl W, Mitchell A W M. Gray’s Anatomy For Students. Churchill Livingstone; 2nd ed. 2010. ISBN 9780808924067. p.424 fig. 5.21
Sacrum• Thisisatriangularbonemadeupof5fused
vertebraeandtheyareoriginaltransverseprocesses.
o Originaltransverseprocessesfusetogethertoformalateralmassandthesuperiorsurfaceofthelateralmassiscalledthesacralala
o Sacralala=thetopofthefusedtransverseprocessesofthesacralvertebraethatcometogether
• TheSuperiorsurfacealsohasamidlineprominencecalledthesacralpromontory.Thesacralalasitsoneithersideofthis
• Sacrumarticulatesabovewiththelumbar-sacraljointabove,belowwiththecoccyxviathesacrococcygealjointandlaterallywiththeileumoneithersideofthesacroiliacjoint
• Iliaccrestandiliacfosseprojectupof
thepelvicbrim• Everythingabovethepelvicbrimis
calledthefalsepelvisorgreaterpelvis(includingiliaccrestandiliacfosse)
• Everythingbelowthepelvicbrimiscalledthetruepelvisorlesserpelvis
• Thelinedelineatingthefalsepelvisfromthetruepelvisistheiliopectinealline.Thisisbasicallythecontinuationofthepectineallineofthepubis
• Thisispartoftheposteriorabdominalwallastheiliacusstartswithinhere
• Thefalsepelvisisreallyconsideredpartoftheposteriorabdominalwallanditformsaprotectionfortheabdominalviscera(andhasnothingtodowiththepelviccontents)
• Thetruepelvis(includingthesacrumandthecoccyx)sitsbetweenthepelvicinletandpelvicoutlet• Tracingalongthepelvicbrim:
o Pelvicinletisboundedbythepubiccrestanteriorly.Thenitfollowsthepectineallineofthepubis.Thereisanarchofthepelvicinletcalledthearcuatelineoftheilium.Thenwegettosacralalaandintothesacralpromontory
Pelvictypes(basedonshapeofinlet)
• Theydifferinshapes• Females–pelvicinletisovalinshapeandwidertransversely–thisisthewidest
transversediameterofthepelviscavity–importantforchildbirtho Gynaecoid–classicfemalepelvicinlet
• Maleo typicalpelvictypeisandroido anthropoidisalsoacommonvariant
• Therearealsootherwaysthatmaleandfemalepelviscandiffer[diagram]
male female
general structure thick and heavy thin and light shape of inlet heart shaped transverse oval 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 the distance from acetabulum to pubic symphysis is greater than the width of the acetabulum. In the male it is about the same.
An@tomedia: Pelvis Systems
1
2
3
4
5
c
promontory ala ala
Sacrum
Netter, F.H. Interactive Atlas of Human Anatomy. 3rd ed. New Jersey, Icon Learning Systems, 2003, ISBN: 1-929007-15-9, Fig. 457B & 335B
lateral mass
lateral mass
LSJ
SCJ
SIJ
An@tomedia: Pelvis Systems
Pelvis (from Latin) = basin
Divided into ‘false’ (greater) & ‘true’ (lesser) pelvis
Iliopectineal line demarcating false pelvis above from true pelvis below
Drake R L, Vogl W, Mitchell A W M. Gray’s Anatomy For Students. Churchill Livingstone; 2nd ed. 2010. ISBN 9780808924067. p.429 fig. 5.28
An@tomedia: Pelvis Systems
Pelvis (from Latin) = basin
Divided into ‘false’ (greater) & ‘true’ (lesser) pelvis
Iliopectineal line demarcating false pelvis above from true pelvis below
Drake R L, Vogl W, Mitchell A W M. Gray’s Anatomy For Students. Churchill Livingstone; 2nd ed. 2010. ISBN 9780808924067. p.429 fig. 5.28
Pelvic types (based on shape of inlet)
An@tomedia: Pelvis Systems
~50%
~30%
~20%
~2%
• Thereisvariationinthegeneralstructure,shapeofinlet,angulationofthegreatersciaticnotch,inthesub-pubicarch,thesizeoftheacetabulumandthesizeoftheobturatorforamen
• Thewidthoftheacetabulumwhencomparedtothewidthofthepubicboneisaparticularlyreliableindexofmaleandfemaledifferences.Inthefemale,thedistancefromacetabulumtopubicsymphysisisgreaterthanthewidthoftheacetabulum.Inthemaleitisaboutthesame
Pubicinlet/outlet
• Pelvicoutletisdiamondshaped• Thisisdefinedasextendingfromthepubicsymphysis
anteriorlytothetipofthecoccyxposteriorly,andeithersidearetheischialtuberosity’s
• Therearevariationsindimensionbetweenmaleandmalebutdiamondshapeisconserved
• Babiesneedtogointhroughtheinletandoutthroughtheoutlet• Planeofleastdimensionpassesthroughtheischialspine,S4andbaseofpubicbone(thisiswherethe
babiesheadgoesthrough)• Duringchildbirth,thebabiesheadrotatesconstantlyandflextopresentsitsnarrowestpartofthebody
(whichisthehead)tothenarrowestopeningofthepelvisJointsofthepelvis
• Thejointsofthepelviscompriseofapairofsynovialjointslaterally(sacroiliacjoints)andsecondarycartilaginousjointsinthemidline(pubicsymphysis)
• Thesacroiliacjointisasynovialjointo Articularsurfaceisanear
shapedsurface/auricularsurfaceoftheposteriorpartofthealaofthesacrumandearshapedsurfaceoftheilium
• Mostimportantpartofthesacroiliacjointsarethesupportingstructures
• Sacroiliacligamentsattachdirectlyanteriorlybetweenthesacrumandtheilium–thisiscalledtheanteriorsacroiliacligament
• Sacroiliacligamentsbehindarecalledposteriorsacroiliacligaments• Theseanteriorandposteriorsacroiliacligamentspassacrossthefrontoftheanteriorandposteriorpartsof
thejointreinforcingthecapsule
Pelvic inlet, narrow pelvic plane & outlet
An@tomedia: Pelvis Systems
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
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
The plane of least dimensions passes through the ischial spine, S4 & base of pubic bone
Pelvic inlet/outlet
An@tomedia: Pelvis Systems
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