SpinalCordandspinalnervesBio230Dr.CarlaSweet

KnowandUnderstandthesedims!!

WheredoestheCNSendandthePNSbegin?

Filum terminalePiathatextendsfromconusmedullaristococcyxbone.AnchorsS.C.inplace

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Spinalcord-extendsfromforamenmagnumtoL1-L2

Conus medullaris- taperingendofspinalcord

Cauda equina (“horsetail”}collectionofnerverootsdistaltospinalcord

Spinalcordgivesriseto31pairsofspinalnerves(PNS)

-8Cervical-12Thoracic-5Lumbar-5Sacral-1Coccygeal

Protection:1.Bone(vertebralcolumn)2.Meninges3.CSF

Anterior

Posterior

Knowthese

*Connectivetissuemembranessurroundingspinalcordandbrain

-Duramater-Arachnoid mater-Pia mater

*Spaces-Epidural:Anesthesiainjected-Subarachnoid:cerebrospinalfluid(CSF)WherespinaltapCSFtakenfrom

Meninges

LumbarPuncture(AKASpinalTap)UsuallydoneL3-L4orL4-L5.WheredoesSpinalcordend?

Lumbarpuncture

WatchonYouTube:https://www.youtube.com/watch?v=-NWJ_iQgxTc

• Whitematter– Myelinated axonsformingtracts– Threefuniculi (columns)

(anterior,lateral,posterior)

• Graymatter– Neuroncellbodieslivehere!

Threehorns(posterior,lateral,anterior)

CrossSectionofSpinalCord

SpinalCordcrosssection–anotherview

Crosssectionofspinalcord

Termstoknowandtheirlocation:Whitecolumns(posterior,lateralandanterior)anterior(ventral)horn;posterior(dorsal)horn;posteriormediansulcus;anteriormedianfissure;dorsalroot,dorsalrootganglion,ventralroot,spinalnerve.Beabletolabelalltheabove,andknowtheirgeneralfunction.

dorsalroot=sensory

ventralroot=motor

O

remember..soma akacellbodyofneuron

Cellbodyofsensory

Cellbodyofmotorneuron

Remember- dprsal rootcontainssensoryfibers(blueinpic),Ventralrootcontainsmotorfibers(red).Thespinalnerveliesattheirjunction(laterally).Justoutsidethevertebralcolumneachspinalnervebranchesintoadorsalramus (branch)andaventralramus whichcontainbothsensoryandmotorfibers.

white&grayramus partofsympatheticdivisionoftheANS

31pairsofSpinalNerves:*8cervical(C1-C8)*12Thoracic(T1-T12)*5Lumbar(L1-L5)*5Sacral(S1-S5*1Coccygeal (CO1)

Knowhowthespinalnervesarenamed.WhyisthereaC8ifonly7cervicalvertebrae?Wewillgooverthisinclass.

Wehavethismodelintheclassroom.Besureyoucanidentify- Cervicalplexus- Brachialplexus- Lumbarplexus- Sacralplexus

Vental Rami toPlexuses.Aspinalnerveisshort(1-2cm),almostimmediatelyafteremergingfromitsintervertebralforamen,itdividesintoasmalldorsalramus andalargerventralramus.

AllVentralrami (exceptT2-T12)branchandjoinoneanotherlateraltothevertebralcolumnformingcomplicatednerveplexuses.ANerveplexusisanetworkofnerves.

Again-onlyventralrami formplexuses.

4plexusesinbody:CervicalBrachialLumbarSacral

formedbyC1-C4

C5-C8&T1

L1-L4

L4-S4

CervicalPlexus-formedbyC1-C4(somebookssayC5)

BrachialPlexus-formedbyC5-C8&T1

LumbarPlexus-formedbyL1-L4

SacralPlexus-formedbyL4- S4

11-16

SpinalNervesCervicalPlexus

• C1-C4• Phrenic nerve

– fromC3-C5– innervatesdiaphragm

Fig.16.8

Cervicle plexuslocation,deepinneckundersternocleidomastoid muscle.

TheONLYCervicle plexusnerveyouneedtoknowisthePhrenic Nerve(C3-5fibers)- inervates diaphragmmuscle.

Phrenic NerveC3-5fibers

C3,4,and5keepthediaphragmalive!

11-19

• C5-T1• Majornerves

– Axillary– Musculcutaneous– Radial– Ulnar– Median

Fig.16.9

BrachialPlexus

BrachialPlexus:Needtoknow:Musculocutaneous nerve,Axillary nerve,Mediannerve,Radialnerve,andUlnar nerve

BrachialPlexus- C5-T1anotherview

Iwillshowyouthe“M“inourcadaver.TheMwillhelpyoulocatethe-MusculocutaneousNerve-MedianNerve-UlnarNerve

11-22

LumbarPlexus-L1-L4

Fig.16.10

Onlyneedtoknow”1.FemoralNerve(ServestheanteriorthighSensoryandmotortoQuadmuscles)

2.Obturatornerve(exitsthruobturatorforamen)ServestheinnerthighregionsensoryandmotortotheAdductormuscles

LumbarPlexusL1-L4Inervates anterior&medialthigh.

Needtoknow:FemoralNerveObturator Nerve

Obturatornerve

LumbarPlexusL1-L5- AnotherviewWhichnervesdoyouneedtoknowfromtheLumbarplexus?

11-25

SacralPlexus-L4-S4

Needtoknow:Sciaticnerveandthetwonervesthatarisefromitup:TheTibial andCommonFibularNerves

SacralPlexus-L4-S4

SciaticNerve(L3-S3)LargestnerveinbodySuppliesallthelowerlimbexceptanteriorandmedialthigh.

Tibial Nerve

SacralPlexus- NeedtoknowSciaticNerveandthe2nervesthatcomefromit:CommonFibular&Tibial

Summary:Besureyoucanfindtheperipheralnervesyouareresponsiblefor:ANDKnowwhatmusclegroupsthensupply.Wewilldothisisclass!

Iwilltrytofindmostofthesenervesinthecadavers.Theoneswecan’tfindwewillusemodels/charts.

WhatisthedifferencebetweenaspinalnerveAndaPeripheralnerve?