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THETHORAX
THORACICWALL
BREAST
THETHORAX
•  THORACICWALL
•  BREAST
THETHORAX
THORACICWALL
THETHORAX
THETHORAX-BONES&JOINTS
Thepartofthebodybetweentheneckandabdomen.
Thethoraciccage(ribcage),withthehorizontalbarsformedbyribs
andcostalcar;lages,isalsosupportedbythever>calsternum
(breastbone)andthoracicvertebrae
Thethoracicskeletonincludes:
•  12pairsofribsandassociatedcostalcar>lages,
•  12thoracicvertebraeandtheintervertebral(IV)discsinterposed
betweenthem,
•  andthesternum.
THERIBS
THETHORAX-BONES&JOINTS
Ribsarecurved,flatbonesthatformmostofthethoraciccage
Therearethreetypesofribsthatcanbeclassifiedastypicalor
atypical:
•  true(vertebrosternal)ribs(1st–7thribs)
•  false(vertebrochondral)ribs(8th,9th,andusually10thribs)
•  floa;ng(vertebral,free)ribs(11th,12th,andsome>mes10thribs)
THERIBS
THETHORAX-BONES&JOINTS
Therearethreetypesofribsthatcanbeclassifiedastypicalor
atypical:
•  true(vertebrosternal)ribs(1st–7thribs):
theyaWachdirectlytothesternumthroughtheirowncostalcar>lages.
•  false(vertebrochondral)ribs(8th,9th,andusually10thribs):
theircar>lagesareconnectedtothecar>lageoftheribabovethem;
thustheirconnec>onwiththesternumisindirect.
•  floa;ng(vertebral,free)ribs(11th,12th,andsome;mes10thribs):
therudimentarycar>lagesoftheseribsdonotconnectevenindirectly
withthesternum;insteadtheyendintheposteriorabdominal
musculature.
THERIBS
THETHORAX-BONES&JOINTS
Typicalribs(3rd–9th)havethefollowingcomponents:
•Head
•Neck
•Tubercle
•Body
Typicalribs(3rd–9th)havethefollowingcomponents:
•Head:hastwofacets,oneforar>cula>onwiththenumerically
correspondingvertebraandonefacetforthevertebrasuperiortoit.
•Neck:connectstheheadoftheribwiththebodyatthe
levelofthetubercle.
•Tubercle:ar>culateswiththecorrespondingtransverseprocessof
thevertebra,
•Body(sha[):thin,flat,andcurved.
THERIBS
THETHORAX-BONES&JOINTS
ATYPICALRIBS(1st,2nd,and10th–12th)aredissimilar:
•  the1stribisthebroadest(i.e.,itsbodyiswidestandnearly
horizontal),shortest,andmostsharplycurved
•  the1stribhasasinglefacetonitsheadforar>cula>onwiththeT1
vertebraonly
•  the1stribhastwotransverselydirectedgroovescrossingits
superiorsurfaceforthesubclavianvessels
•  the1stribhasthegroovesseparatedbyascalenetubercleand
ridge,towhichtheanteriorscalenemuscleisaWached.
THERIBS
THETHORAX-BONES&JOINTS
Atypicalribs(1st,2nd,and10th–12th)aredissimilar:
•  the2ndribishasathinner,lesscurvedbody
•  hastwofacetsforar>cula>onwiththebodiesoftheT1andT2
vertebrae
Atypicalribs(1st,2nd,and10th–12th)aredissimilar:
•  The10th–12thribs,likethe1strib,haveonlyonefaceton
theirheadsandar;culatewithasinglevertebra.
Atypicalribs(1st,2nd,and10th–12th)aredissimilar:
•The11thand12thribsareshortandhavenoneckor
tubercle.
THECOSTALCARTILAGES
THETHORAX-BONES&JOINTS
Costalcar;lagesprolongtheribsanteriorlyandcontributetothe
elas>cityofthethoracicwall,providingaflexibleaWachment
fortheiranteriorends(>ps).
Intercostalspacesseparatetheribsandtheircostalcar>lagesfromone
another
THETHORACICVERTEBRAE
THETHORAX-BONES&JOINTS
Characteris>cfeaturesofthoracicvertebraeinclude:
•  Bilateralcostalfacets(demifacets)onthevertebralbodies,usually
occurringininferiorandsuperiorpairs,forar>cula>onwiththe
headsofribs.
•  Costalfacetsonthetransverseprocessesforar>cula>onwiththe
tuberclesofribs,exceptfortheinferiortwoorthreethoracic
vertebrae.
•  Long,inferiorlyslan>ngspinousprocesses.
THETHORACICVERTEBRAE
THETHORAX-BONES&JOINTS
Superiorandinferiorcostalfacetsoccurasbilaterallypaired,planar
surfacesonthesuperiorandinferiorposterolateralmarginsofthe
bodiesoftypicalthoracicvertebrae(T2–T9).
Atypicalthoracicvertebrae:
•  ThesuperiorcostalfacetsofvertebraT1arenotdemifacetsbecause
therearenodemifacetsontheC7vertebraabove,andrib1
ar;culatesonlywithvertebraT1.T1hasatypicalinferiorcostal
facet.
•  T10hasonlyonebilateralpairof(whole)costalfacets,located
partlyonitsbodyandpartlyonitspedicle.
•  T11andT12alsohaveonlyasinglepairof(whole)costalfacets,
locatedontheirpedicles.
THESTERNUM
THETHORAX-BONES&JOINTS
Thesternumistheflat,elongatedbonethatformsthemiddleofthe
anteriorpartofthethoraciccage.
Thesternumconsistsofthreeparts:
•  manubrium,
•  body,and
•  xiphoidprocess
THESTERNUM
THETHORAX-BONES&JOINTS
Theeasilypalpatedconcavecenterofthesuperiorborderofthe
manubriumisthejugularnotch(suprasternalnotch).
Thejugularnotchliesattheleveloftheinferiorborderofthebodyof
T2vertebraandthespacebetweenthe1stand2ndthoracicspinous
processes.
Themanubriumandbodyofthesternumlieinslightlydifferentplanes
superiorandinferiortotheirjunc>on,
themanubriosternaljoint;
hence,theirjunc>onformsaprojec>ngsternalangle(ofLouis).
Inferolateraltotheclavicularnotch,thecostalcar>lageofthe1stribis
>ghtlyaWachedtothelateralborderofthemanubrium–
-thesynchondrosisofthefirstrib
THESTERNUM
THETHORAX-BONES&JOINTS
Thebodyofthesternum,islonger,narrower,andthinnerthanthe
manubrium,andislocatedattheleveloftheT5–T9vertebrae
Thexiphoidprocess,thesmallestandmostvariablepartofthe
sternum,isthinandelongated.ItsinferiorendliesatthelevelofT10
vertebra.
THESTERNUM
THETHORAX-BONES&JOINTS
Thexiphisternaljointisamidlinemarkerforthesuperiorlimitofthe
liver,thecentraltendonofthediaphragm,andtheinferiorborderof
theheart.
JOINTSOFTHORACICWALL
•  Intervertebral(ofvertebraeT1–T12)
•  Costovertebral(jointsofheadofrib)
•  Costochondral
•  Interchondral
•  Sternocostal
•  Sternoclavicular
•  Manubriosternal
•  Xiphisternal
THETHORAX-BONES&JOINTS
JOINTSOFTHORACICWALL
THETHORAX-BONES&JOINTS
JOINTSOFTHORACICWALL
THETHORAX-BONES&JOINTS
THETHORAX-BONES&JOINTS
THETHORACICAPERTURES
THETHORACICAPERTURES
THETHORAX-BONES&JOINTS
Whilethethoraciccageprovidesacompletewallperipherally,itis
opensuperiorlyandinferiorly.
Themuchsmallersuperioropening(aperture)isapassagewaythat
allowscommunica>onwiththeneckandupperlimbs.
Thelargerinferioropeningprovidesthering-likeoriginofthe
diaphragm,whichcompletelyoccludestheopening.
THETHORACICAPERTURES
THETHORAX-BONES&JOINTS
TheSUPERIORTHORACICAPERTUREisbounded:
•Posteriorly,byvertebraT1,thebodyofwhichprotrudes
anteriorlyintotheopening.
•Laterally,bythe1stpairofribsandtheircostalcar>lages.
•Anteriorly,bythesuperiorborderofthemanubrium.
THETHORACICAPERTURES
THETHORAX-BONES&JOINTS
THETHORACICINLET
Space-occupyingtumoursinthisloca>onmaycompressadjacent
structures,leadingtotheclinicalcondi>oncalledthoracicoutlet
syndrome.
THETHORACICAPERTURES
THETHORAX-BONES&JOINTS
Inferiorlythecavityofthethoraxisseparatedfromtheabdominal
contentsbyafibromuscularsheetcalledthediaphragm.
Thefloorofthethoraciccavity(thoracicdiaphragm)isdeeply
invaginatedinferiorly(i.e.,ispushedupward)byvisceraofthe
abdominalcavity.
THETHORAX-BONES&JOINTS
THETHORACICAPERTURES
TheINFERIORTHORACICAPERTUREisboundedasfollows:
•Posteriorly,bythe12ththoracicvertebra,thebodyofwhich
protrudesanteriorlyintotheopening.
•Posterolaterally,bythe11thand12thpairsofribs.
•Anterolaterally,bythejoinedcostalcar>lagesofribs7–10,forming
thecostalmargins.
•Anteriorly,bythexiphisternaljoint.
THEMUSCLESOFTHETHORAX
MUSCLESOFTHORACICWALL
THETHORAX
THEMUSCLESOFTHETHORAX
MUSCLESOFTHEPECTORALREGION:
•  Lateralandmedialpectoralnerves
•  Pectoralismajor
•  Subclavius
•  Nervetosubclavius
•  Pectoralisminor
•  Medialpectoralnerve
Thepectoralismajormuscleisthelargestandmostsuperficialofthe
pectoralregionmuscles.
Thesubclaviusandpectoralisminormusclesunderliepectoralis
major:
•  subclaviusissmallandpasseslaterallyfromtheanteriorand
medialpartofribItotheinferiorsurfaceoftheclavicle;
•  pectoralisminorpassesfromtheanteriorsurfacesofribsIIItoVto
thecoracoidprocessofthescapula.
THETHORAX
THEMUSCLESOFTHETHORAX
Themusclesofthepectoralregionformtheanteriorwalloftheaxilla,
aregionbetweentheupperlimbandtheneckthroughwhichallmajor
structurespass.
Nerves,vessels,andlympha>csthatpassbetweenthepectoral
regionandtheaxillapassthroughtheclavipectoralfasciabetween
subclaviusandpectoralisminororpassundertheinferiormarginsof
pectoralismajorandminor.
THEMUSCLESOFTHETHORAX
THEMUSCLES
Thetruemusclesofthethoracicwallarethe:
serratusposterior,levatorescostarum,intercostal,subcostal,
andtransversusthoracis.
THEMUSCLESOFTHETHORAX
THEMUSCLES
Thelevatorescostarummusclesare12fan-shapedmusclesthat
elevatetheribs,buttheirrole,ifany,innormalinspira>onis
uncertain.
Theintercostalmusclesoccupytheintercostalspaces
Thesuperficiallayer-theexternalintercostals,theinnerlayer-the
internalintercostals.Thedeepestfibers-theinnermostintercostals.
Theexternalintercostalmuscles(11pairs)occupytheintercostal
spacesfromthetuberclesoftheribsposteriorlytothecostochondral
junc>onsanteriorly.
THEMUSCLESOFTHETHORAX
THEMUSCLES
Theexternalintercostalmusclesarecon>nuousinferiorlywiththe
externalobliquemusclesintheanterolateralabdominalwall.
Theinternalintercostalmuscles(11pairs)rundeeptoandatright
anglestotheexternalintercostals.
Betweentheribsposteriorly,medialtotheangles,theinternal
intercostalsarereplacedbytheinternalintercostalmembranes.
Theinferiorinternalintercostalmusclesarecon>nuouswiththe
internalobliquemusclesintheanterolateralabdominalwall.
Theinnermostintercostalmusclesaresimilartotheinternal
intercostalsandareessen>allytheirdeeperparts.
Theinnermostintercostalsareseparatedfromtheinternal
intercostalsbyintercostalnervesandvessels
THEMUSCLESOFTHETHORAX
THEMUSCLES
Thesubcostalmusclesarevariableinsizeandshape,usuallybeing
welldevelopedonlyinthelowerthoracicwall.
Thetransversusthoracismusclesconsistoffourorfive
slipsthatradiatesuperolaterallyfromtheposterioraspect
oftheinferiorsternum.
Theexternalandinternalintercostalsareac>veduringinspira;on
andexpira;on.Theroleofthesemusclesinproducingmovementof
theribsappearstoberelatedmainlytoforcedrespira;on.
Theprimaryroleoftheintercostalmusclesinrespira>onistosupport
(increasethetonusorrigidityof)theintercostalspace.
Thediaphragmistheprimarymuscleofinspira>on.
THERESPIRATORYSYSTEM
NERVESOFTHETHORACICWALL
The12pairsof
thoracicspinal
nervessupplythe
thoracic
wall.
AssoonastheyleavetheIVforaminain
whichtheyareformed,themixed
thoracicspinalnervesdivideinto
anteriorandposterior(primary)ramior
branches
Theanteriorramiof
nervesT1–T11form
theintercostalnerves
thatrunalongtheextent
oftheintercostalspaces.
THERESPIRATORYSYSTEM
NERVESOFTHETHORACICWALL
Neartheanglesoftheribs,thenervespassbetweentheinternal
intercostalandtheinnermostintercostalmuscles.
Atthispoint,theintercostalnervespasstoandthencon>nueto
courseinorjustinferiortothecostalgrooves,runninginferiortothe
intercostalarteries.
THERESPIRATORYSYSTEM
NERVESOFTHETHORACICWALL
Thebranchesofatypicalintercostalnerveare:
•  Ramicommunicantes,orcommunica>ngbranches,thatconnect
eachintercostalnervetotheipsilateralsympathe>ctrunk.
•  Collateralbranchesthatariseneartheanglesoftheribs
•  LateralcutaneousbranchesthatariseneartheMAL
•  Anteriorcutaneousbranchespiercethemusclesandmembranes
oftheintercostalspace
•  Muscularbranchesthatsupplytheintercostal,subcostal,
transversusthoracis,levatorescostarum,andserratusposterior
muscles
ARTERIESOFTHORACICWALL
THERESPIRATORYSYSTEM
Thearterialsupplytothethoracicwallderivesfromthe:
•  Thoracicaorta,throughtheposteriorintercostalandsubcostal
arteries.
•  Subclavianartery,throughtheinternalthoracicandsupreme
intercostalarteries.
•  Axillaryartery,throughthesuperiorandlateralthoracicarteries.
Theintercostalarteriescoursethroughthethoracicwall
betweentheribs.
Eachintercostalspaceissuppliedbythreearteries:alarge
posteriorintercostalartery(anditscollateralbranch)anda
smallpairofanteriorintercostalarteries.
VEINSOFTHORACICWALL
THERESPIRATORYSYSTEM
Thereare11posteriorintercostalveinsandonesubcostalveinon
eachside.Theposteriorintercostalveinsanastomosewiththe
anteriorintercostalveins(tributariesofinternalthoracicveins).
Mostposteriorintercostalveins(4–11)endintheazygos/hemiazygosvenoussystem,whichconveysvenousbloodtothesuperior
venacava(SVC).
Theposteriorintercostalveinsofthe1stintercostalspaceusually
enterdirectlyintotherightandle[brachiocephalicveins.
THERESPIRATORYSYSTEM
THEBREASTS
BREASTS
THEBREASTS
Thebreastsconsistofglandularandsuppor>ngfibrous
;ssueembeddedwithinafaWymatrix,togetherwithblood
vessels,lympha>cs,andnerves.
Themammaryglandsareinthesubcutaneous>ssueoverlyingthe
pectoralismajorandminormuscles.
Atthegreatestprominenceofthebreastisthenipple,surrounded
byacircularpigmentedareaofskin,theareola
Theroughlycircularbodyofthefemalebreastrestsonabedofthe
breastthatextendstransverselyfromthelateralborderofthe
sternumtothemidaxillarylineandver>callyfromthe2ndthrough
6thribs.
FEMALEBREASTS
THEBREASTS
Twothirdsofthebedareformedbythepectoralfasciaoverlying
thepectoralismajor;theotherthird,bythefasciacoveringthe
serratusanterior.
Betweenthebreastandthepectoralfasciaisaloosesubcutaneous
>ssueplaneorpoten>alspace–
-theretromammaryspace.
Asmallpartofthemammaryglandmayextendalongthe
inferolateraledgeofthepectoralismajortowardtheaxillaryfossa
(armpit),forminganaxillaryprocessortail(ofSpence).
ThemammaryglandsarefirmlyaWachedtothedermisofthe
overlyingskin,especiallybysubstan>alskinligaments,
thesuspensoryligamentsofCooper.
FEMALEBREASTS
THEBREASTS
Thesecondensa>onsoffibrousconnec>ve>ssue,par>cularlywell
developedinthesuperiorpartofthegland,helpsupportthelobes
andlobulesofthemammarygland.
Thelac;ferousductsgiverisetobudsthatdevelopinto15–20
lobulesofthemammarygland,whichcons>tutetheparenchyma
(func>onalsubstance)ofthemammarygland.
Thuseachlobuleisdrainedbyalac;ferousduct.
Eachducthasadilatedpor>ondeeptotheareola,thelac;ferous
sinus,inwhichasmalldropletofmilkaccumulates
orremainsinthenursingmother.
Theareolaecontainnumeroussebaceousglands,whichenlarge
duringpregnancyandsecreteanoilysubstance
FEMALEBREASTS
THEBREASTS
Thenipplesareconicalorcylindricalprominencesinthecentersof
theareolae.
Themammaryglandsaremodifiedsweatglands;therefore,they
havenocapsuleorsheath.
Inmostwomen,thebreastsenlargeslightlyduringthemenstrual
periodfromincreasedreleaseofgonadotropichormones:follicles;mula;nghormone(FSH)andluteinizinghormone(LH)-onthe
glandular>ssue.
VASCULATUREOFBREASTS
THEBREASTS
Thearterialsupplyofthebreastderivesfromthe:
•  Medialmammarybranchesofperfora>ngbranchesandanterior
intercostalbranchesoftheinternalthoracicartery,origina>ng
fromthesubclavianartery.
•  Lateralthoracicandthoraco-acromialarteries,branchesofthe
axillaryartery.
•  Posteriorintercostalarteries,branchesofthethoracicaortainthe
2nd,3rd,and4thintercostalspaces.
Thevenousdrainageofthebreastismainlytotheaxillaryvein,but
thereissomedrainagetotheinternalthoracicvein.
VASCULATUREOFBREASTS
THEBREASTS
Thelympha;cdrainageofthebreastisimportantbecauseofitsrole
inthemetastasisofcancercells.
Lymphpassesfromthenipple,areola,andlobulesoftheglandtothe
subareolarlympha;cplexus.
VASCULATUREOFBREASTS
THEBREASTS
Fromthesubareolarlympha;cplexus:
•  mostlymph(>75%),especiallyfromthelateralbreastquadrants,
drainstotheaxillarylymphnodes,ini>allytotheanterioror
pectoralnodesforthemostpart.
•  mostoftheremaininglymph,par>cularlyfromthemedialbreast
quadrants,drainstotheparasternallymphnodesortothe
oppositebreast.
•  lymphfromtheinferiorquadrantsmaypassdeeplytoabdominal
lymphnodes(subdiaphragma>cinferiorphreniclymphnodes).
VASCULATUREOFBREASTS
THEBREASTS
Lymphfromtheaxillarynodesdrainsintoclavicular(infraclavicular
andsupraclavicular)lymphnodesandfromthemintothesubclavian
lympha;ctrunk,whichalsodrainslymphfromtheupperlimb.
Lymphfromtheparasternalnodesentersthebronchomedias>nal
lympha>ctrunks,whichalsodrainlymphfromthethoracicviscera.
Thetermina>onofthelympha>ctrunksvaries.
Thesetrunksaredescribedasmergingwitheachotherandwiththe
jugularlympha;ctrunk,drainingtheheadandnecktoformashort
rightlympha;cductontherightsideorenteringthetermina>onat
thethoracicductonthele[side.
VASCULATUREOFBREASTS
THEBREASTS
Thetrunksopenindependentlyintothejunc>onoftheinternal
jugularandsubclavianveins,therightorledvenousangles,that
formtherightandle[brachiocephalicveins.
NERVESOFBREASTS
THEBREASTS
Thenervesofthebreastderivefromanteriorandlateralcutaneous
branchesofthe4th-6thintercostalnerves.
Thebranchesoftheintercostalnervesconvey:
•  sensoryfibersfromtheskinofthebreast
•  sympathe;cfiberstothebloodvesselsinthebreastsandsmooth
muscleintheoverlyingskinandnipple.