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THEBACK
THEMUSCLES
THEMUSCLESOFTHEBACK
THEMUSCLESOFTHEBACK
Musclesofthebackareorganizedintosuperficial,intermediate,and
deepgroups.
extrinsicmusclesandintrinsicmuscles
Musclesinthesuperficial
andintermediategroupsareextrinsicmusclesbecausethey
originateembryologicallyfromlocaFonsotherthantheback.
THEMUSCLESOFTHEBACK
Thesuperficialandintermediategroupsareinnervatedbyanterior
ramiofspinalnerves.
Thesuperficialgroupconsistsofmusclesrelatedtoandinvolvedin
movementsoftheupperlimb.
TheintermediategroupconsistsofmusclesaHached
totheribs
andmayservearespiratoryfuncFon.
Musclesofthedeepgroup
areintrinsicmusclesbecausetheydevelopintheback.
THEMUSCLESOFTHEBACK
Thedeepgroupareareinnervatedbyposteriorramiofspinalnerves
andaredirectlyrelatedto
movementsofthevertebralcolumnandhead.
THEBACKMUSCLES
•  SUPERFICIALEXTRINSICBACKMUSCLES
•  INTERMEDIATEEXTRINSICBACKMUSCLES
•  DEEPINTRINSICBACKMUSCLES
SUPERFICIALGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
ThemusclesintheSUPERFICIALGROUPareimmediatelydeeptothe
skinandsuperficialfascia.
TheyaHachthesuperiorpartoftheappendicularskeleton:
•  clavicle
•  scapula
•  humerus
totheaxialskeleton:
•  skull
•  ribs
•  vertebralcolumn.
SUPERFICIALGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
Becausethesemusclesareprimarilyinvolvedwithmovementsofthis
partoftheappendicularskeleton,theyaresomeFmesreferredtoas
theappendiculargroup.
Musclesinthesuperficialgroupincludethe:
•  trapezius
•  laMssimusdorsi
•  rhomboidmajor
•  rhomboidminor
•  levatorscapulae
Therhomboidmajor,rhomboidminor,andlevatorscapulaemuscles
arelocateddeeptothetrapeziusmuscleinthesuperiorpartofthe
back.
SUPERFICIALGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
THETRAPEZIUS
THETRAPEZIUSMUSCLE
THEMUSCLESOFTHEBACK
Eachtrapeziusmuscleisflatandtriangular,withthebaseofthe
trianglesituatedalongthevertebralcolumn(themuscle'sorigin)and
theapexpoinFngtowardtheFpoftheshoulder(themuscle's
inserFon)
Themusclesonbothsidestogetherformatrapezoid.
Thesuperiorfibersofthetrapezius,fromtheskullandupperporFon
ofthevertebralcolumn,descendtoaHachtothelateralthirdofthe
clavicleandtotheacromionofthescapula.
ContracFonofthesefibers
elevatesthescapula.
THETRAPEZIUSMUSCLE
THEMUSCLESOFTHEBACK
Thesuperiorandinferiorfibersworktogethertorotatethelateral
aspectofthescapulaupward-whenraisingtheupperlimbabovethe
head.
ORIGIN:
Superiornuchalline,externaloccipitalprotuberance,ligamentum
nuchae,spinousprocessesofCVIItoTXII
INSERTION:
Lateralonethirdofclavicle,acromion,spineofscapula.
FUNCTION:
AssistsinrotaFngthe
INNERVATION:
scapuladuringabducFon
Motor:
ofhumerusabove
accessorynerve[XI];
horizontal;upperfibers
elevate,middlefibers
propriocepFon:
adduct,andlowerfibers
C3andC4
depressscapula.
SUPERFICIALGROUPOFBACKMUSCLES
THELATISSIMUSDORSI
THEMUSCLESOFTHEBACK
THELATISSIMUSDORSI
THEMUSCLESOFTHEBACK
Alarge,flattriangularmusclethatbeginsinthelowerporMonofthe
backandtapersasitascendstoanarrowtendonthataHachestothe
humerusanteriorly
Themovementsassociatedwiththismuscleinclude:
•  extension
•  adducFon
•  medialrotaFonoftheupperlimb.
ThelaFssimusdorsicanalsodepresstheshoulder,prevenFngits
upwardmovement.
Thethoracodorsalnerveofthebrachialplexus(fromposteriorcord)
innervatesthelaFssimusdorsimuscle.
THELATISSIMUSDORSI
THEMUSCLESOFTHEBACK
ORIGIN:
SpinousprocessesofTVIItoLVandsacrum,iliaccrest,ribsXtoXII
INSERTION:
Floorofintertubercularsulcusofhumerus
INNERVATION:
Thoracodorsalnerve(C6toC8).
FUNCTION:
Extends,adducts,andmediallyrotateshumerus.
SUPERFICIALGROUPOFBACKMUSCLES
THELEVATORSCAPULAE
THEMUSCLESOFTHEBACK
THELEVATORSCAPULAE
THEMUSCLESOFTHEBACK
Aslendermusclethatdescendsfromthetransverseprocessesofthe
uppercervicalvertebraetotheupperporFonofthescapulaonits
medialborderatthesuperiorangle
ItelevatesthescapulaandmayassistothermusclesinrotaFngthe
lateralaspectofthescapulainferiorly.
Thelevatorscapulaeisinnervatedbybranchesfromtheanteriorrami
ofspinalnervesC3andC4andthedorsalscapularnerve
ORIGIN:
TransverseprocessesofCItoCIV
INSERTION:
UpperporFonofmedialborderofscapula
INNERVATION:
C3toC4anddorsalscapularnerve(C4,C5).
FUNCTION:
Elevatesscapula
SUPERFICIALGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
THERHOMBOIDMINOR
AND
THERHOMBOIDMAJOR
THERHOMBOIDMUSCLES
THEMUSCLESOFTHEBACK
Thetworhomboidmusclesareinferiortolevatorscapulae
Rhomboidminorissuperiortorhomboidmajor.
Therhomboidminorarisesfromtheligamentumnuchaeoftheneck
andthespinousprocessesofvertebraeCVIIandTIandaHachestothe
medialscapularborderoppositetherootofthespineofthescapula.
Therhomboidmajororiginatesfromthespinousprocessesofthe
upperthoracicvertebraeTII–TVandaHachestothemedialscapular
borderinferiortorhomboidminor.
Thetworhomboidmusclesworktogethertoretract
orpullthescapulatowardthevertebralcolumn.
Thedorsalscapularnerve(C4,C5),abranchofthebrachialplexus,
innervatesbothrhomboidmuscles
THEBACKMUSCLES
•  SUPERFICIALEXTRINSICBACKMUSCLES
•  INTERMEDIATEEXTRINSICBACKMUSCLES
•  DEEPINTRINSICBACKMUSCLES
INTERMEDIATEGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
Themusclesintheintermediategroupofbackmusclesconsistoftwo
thinmuscularsheetsinthesuperiorandinferiorregionsoftheback
Fibersfromthesetwoserratusposteriormuscles:serratusposterior
superiorandserratusposteriorinferiorpassobliquelyoutwardfrom
thevertebralcolumntoaHachtotheribs.
ThisposiFoningsuggestsarespiratoryfuncFon
Serratusposterior
superiorisdeeptothe
rhomboidmuscles
Serratusposteriorinferioris
deeptothelaFssimusdorsi
BothserratusposteriormusclesareaHachedto
thevertebralcolumn.
INTERMEDIATEGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
ThefibersoftheserratusposteriorsuperiorDESCENDtoaHachto
theribs.
ThefibersoftheserratusposteriorinferiorASCENDtoaHachtothe
ribs.
Theserratusposteriormusclesareinnervatedbysegmentalbranches
ofanteriorramiofintercostalnerves.
THEBACKMUSCLES
•  SUPERFICIALEXTRINSICBACKMUSCLES
•  INTERMEDIATEEXTRINSICBACKMUSCLES
•  DEEPINTRINSICBACKMUSCLES
DEEPGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
Thedeeporintrinsicmusclesofthebackextend
fromthepelvistotheskull
Thedeepmusclesofthebackareinnervatedbysegmentalbranches
oftheposteriorramiofspinalnerves.
Deepgroupofbackmuscles:
•  theextensorsandrotatorsoftheheadandneck-thesplenius
capiFsandcervicis(spinotransversalesmuscles),
•  theextensorsandrotatorsofthevertebralcolumn-theerector
spinaeandtransversospinales,
•  theshortsegmentalmuscles-theinterspinalesand
intertransversarii.
DEEPGROUPOFBACKMUSCLES
Thedeeporintrinsicmusclesincludethe:
•  spinotransversales
•  erectorspinae
•  transversospinales
•  segmental
•  suboccipitalmuscles
THEMUSCLESOFTHEBACK
DEEPGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
SPINOTRANSVERSALESMUSCLES
Thetwospinotransversalesmusclesrunfromthespinousprocesses
andligamentumnuchae.
SPINOTRANSVERSALESMUSCLES:
•  SpleniuscapiMsisabroadmuscleaHachedtotheoccipitalbone
andmastoidprocessofthetemporalbone.
•  SpleniuscervicisisanarrowmuscleaHachedtothetransverse
processesoftheuppercervicalvertebrae.
SPINOTRANSVERSALESMUSCLES
InnervaMon:Posteriorramimiddlecervicalnerves DEEPGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
ERECTORSPINAE
Theerectorspinaeisthelargestgroupofintrinsicbackmuscles.
ERECTORSPINAE
Theouterormostlaterallyplacedcolumnoftheerectorspinae
musclesistheiliocostalis.
ERECTORSPINAE
Theouterormostlaterallyplacedcolumnoftheerectorspinae
musclesistheiliocostalis.
Themiddleorintermediatecolumnisthelongissimus.
Themostmedialmusclecolumnisthespinalis.
ERECTORSPINAE
Themuscleslieposterolaterallytothevertebralcolumnbetweenthe
spinousprocessesmediallyandtheanglesoftheribslaterally.
DEEPGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
ERECTORSPINAE
Themusclesintheerectorspinaegrouparetheprimaryextensorsof
thevertebralcolumnandhead.
ERECTORSPINAE
AcFngunilaterally,theybendthevertebralcolumnlaterally.
DEEPGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
TRANSVERSOSPINALES
Thetransversospinalesmusclesrunobliquelyupwardandmedially
fromtransverseprocessestospinousprocesses
TRANSVERSOSPINALES
FillingthegroovebetweenthesetwovertebralprojecFons.
TRANSVERSOSPINALES
Theyaredeeptotheerectorspinae
TRANSVERSOSPINALES
Threemajorsubgroups:
•  semispinalis
•  mulFfidus
•  rotatoresmuscles
DEEPGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
TRANSVERSOSPINALES
Whenmusclesinthetransversospinalesgroupcontractbilaterally,
theyextendthevertebralcolumn
acFonsimilartothat
oftheerector
spinaegroup
TRANSVERSOSPINALES
Onemuscleinthisgroup,thesemispinaliscapiMs,hasauniqueacFon
becauseitaHachestotheskull.
TRANSVERSOSPINALE-thesemispinaliscapiMs:
ContracFngbilaterally,thismusclepullstheheadposteriorly
TRANSVERSOSPINALE-thesemispinaliscapiMs:
unilateralcontracFonpullstheheadposteriorlyandturnsit
DEEPGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
SEGMENTALMUSCLES
Thetwogroupsofsegmentalmuscles:
•  thefirstgroupofsegmentalmusclesarethelevatorescostarum
muscles.
•  thesecondgroupofsegmentalmusclesarethetruesegmental
musclesoftheback-theinterspinalesandtheintertransversarii.
THEMUSCLESOFTHEBACK
THETHORACOLUMBARFASCIA
DEEPGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
ThethoracicandlumbarpartsofthedeepfasciaconsFtutethe
thoracolumbarfascia.
DEEPGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
ThethoracolumbarfasciaiscriFcaltotheoverallorganizaFonand
integrityoftheregion:
•  Superiorly,itpassesanteriorlytotheserratusposteriormuscleand
isconFnuouswithdeepfasciaintheneck.
•  Inthethoracicregion,itcoversthedeepmusclesandseparates
themfromthemusclesinthesuperficialandintermediategroups.
•  Medially,itaHachestothespinousprocessesofthethoracic
vertebraeand,laterally,totheanglesoftheribs.
DEEPGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
SUBOCCIPITALMUSCLES
Asmallgroupofdeepmusclesintheuppercervicalregionatthebase
oftheoccipitalbone
SUBOCCIPITALMUSCLESinclude,oneachside:
•  rectuscapiFsposteriormajor,
INNERVATION:
•  rectuscapiFsposteriorminor,
posteriorramusofC1
•  obliquuscapiFsinferior,
•  obliquuscapiFssuperior
SUBOCCIPITALMUSCLES
ContracFonofthesuboccipitalmusclesextendstheheadatthe
atlantoaxialjoint.
DEEPGROUPOFBACKMUSCLES
THEMUSCLESOFTHEBACK
SUBOCCIPITALMUSCLES
Thesuboccipitalmusclesformtheboundariesofthesuboccipital
triangle
SUBOCCIPITALMUSCLES
Thecontentsofthesuboccipitaltriangleare
•  theposteriorramusofC1,
•  thevertebralartery,
•  andassociatedveins.
THEMUSCLESOFTHEBACK
NERVEINJURIES
AFFECTINGSUPERFICIALBACKMUSCLES
THEMUSCLESOFTHEBACK
AninterrupFonoftheaccessorynerve[XI]…
Theaccessorynerve[XI]innervates:
THETRAPEZIUS-funcMon:
AssistsinrotaFngthescapuladuringabducFonofhumerusabove
horizontal;upperfiberselevatescapula…
SYMPTOMS:
•  droopingoftheshoulder
•  inabilitytoraisethearmabovetheheadbecauseofimpaired
rotaFonofthescapula
•  weaknessinaHempFngtoraisetheshoulder