GrossAnatomy• Size:42-45cmlong• Regions
– Cervical• Continuouswithmedullaoblongata• Motorneuronsformcervicalspinalnerves
– Thoracic• Motorneuronsformthoracicspinalnerves
– Lumbar• Motorneuronsforlumbarspinalnerves
– Sacral• Motorneuronsforsacralspinalnerves
– Coccygeal
Note:doesn’tmatchupexactlytovertebrae
Regions• Cervicalenlargement– Innervatesupperlimbs
• Lumbarenlargement– Innervateslowerlimbs
• Conusmedullaris=endofthespinalcord– Caudaequina=axons– Filumterminale(alsocalledthecoccygealligament)=piamaterthatanchorsconusmedularistococcyx
Meninges• Piamater– Denticulateligaments– Coccygealligament– Formalateralshelfseparatingthedorsalandventralrootlets
• Arachnoidmater– Subarachnoidspace– CSF
• Duramater• Onlyonelayerinthe
spinalcord• Epiduralspace
RegionalDifferences
Region Diameter Shape Ratio
Cervical Largest(10-15mm)
Ovalwithflattening
h whitevsgray
Thoracic Smaller Ovalwithflattening
h whitevsgray
Lumbar >thoracic Almostcircular
i white
Sacral Smallest Almostcircular
white=gray
SpinalCordWhiteMatter
• Columns– segmentsofmyelinatedaxonsthatleadup/downthespinalcord
• Ascendingtracts– leadupthespinalcordtothebrain– Example:spinothalmictract
• Descendingtracts– leadfromthebraindowntothespinalcord– Example:corticospinaltract
SpinothalamicTract
• SpinothalamicTract– Infotothalamus• Pain• Temperature• Itch• Crudetouch
–Decussatesinspinalcord–Receivessensoryinformationfromskin,viscera
CorticospinalTract
• OneofthePyrimidalTractsofthemedullaoblongata• Fromcerebralcortextomotorneuronsinthespinalcord• Controlsmovementsoflimbsandtrunk• Decussationinthemedulla–Decussationofthepyramids–About80%
SpinalNerves
• ConnectCNStomuscles,receptors,glands
• 31pairs• 8pairsCervical• 12pairsThoracic• 5pairsLumbar• 5pairsSacral• 1pairsCoccygeal
AnatomyofaPeripheralNerve• Eachperipheralnervehas3layersofconnectivetissue• Epineurium– Surroundstheoutersurfaceofthenerve– DenseirregularCT– Blood-nervebarrier
• Perineurium– Enclosesbundlesofaxons– Fascicles
• Endoneurium– Areolar CT– CapillarieswithinsupplyoxygenandnutrientstotheaxonsandSchwanncells
PeripheralDistributionofSpinalNerves
• Eachspinalnerveisformedfromthefusionofdorsalandventralrootsastheypassthroughtheintervertebralforamen
• Nervesthendivideintoseveralbranches
NervePlexuses• Segmentscontrollingskeletal
musculature– Neck– Upperlimbs– Lowerlimbs
• Ventralrami ofadjacentspinalnervesblendtheirfiberstoformaseriesofcompoundnervetrunks
• Nervesplexuses– Cervical– Brachial– Lumbar– Sacral
• Occursduringskeletalmuscledevelopment
CranialNerves
• 12pairs– Arisefromtheinferioraspectofthebrain
– 2fromtheforebrain– 10fromthebrainstem
• Functions– Sensory– Motor– ….orboth
CranialNervesCNI OlfactoryNerve Oh Some
CNII OpticNerve Oh Say
CNIII OculomotorNerve Oh Marry
CNIV TrochlearNerve To Money
CNV TrigeminalNerve Touch But
CNVI AbducensNerve And My
CNVII FacialNerve Feel Brother
CNVIII VestibulocochlearNerve Very Says
CNIX GlossopharyngealNerve Good Big
CNX VagusNerve Velvet Brains
CNXI AccessoryNerve A Matter
CNXII HypoglossalNerve H Most