感覺神經系統癥狀苗旺GENERALPROPERTIESOFSENSORYSYSTEMSFigure10-4:Sensorypathways1.SENSORYRECEPTORSA:Freenerveendings(pain,temperature)B:Paciniancorpuscle(pressure)C:Meissner’scorpuscle(touch)D:Musclespindle(stretch)ABCDRuffini'sendingsrespondtotensionandstretchintheskin

SEGMENTALINNERVATION(DERMATOMES)

PERIPHERALINNERVATION

感覺傳導路由三級神經元組成：第Ⅰ級神經元:胞體位于脊髓后根神經節或腦神經感覺神經節

第Ⅱ級神經元:胞體位于脊髓后角細胞及延髓薄束核、楔束核或腦干腦神經核

第Ⅲ級神經元:胞體位于丘腦感覺接替核2.淺感覺傳導路:前外側系統theanterolateralsystem

(先交叉，后上行)輕觸-壓覺,痛覺,溫度覺的傳入纖維↓經后根節外側部(細纖維部分)↓進入脊髓后角并于此換元↓換元后的第Ⅱ級神經元發出纖維↓在中央管前交叉到對側↓沿脊髓丘腦前束、脊髓丘腦側束↓上行到達丘腦感覺接替核SOMATICPATHWAYSFigure10-9:Sensorypathwayscrossthebody’smidlineImpulsestransmittedtospinalcordbyMyelinatedAδnerves:fastpain(80m/s)UnmyelinatedCnerves:slowpain(0.4m/s)nociceptornociceptorAδnerveCnervespinothalamicpathwaytoreticularformationImpulsesascendtosomatosensorycortexvia:Spinothalamicpathway(fastpain)Reticularformation(slowpain)reticularformationspinothalamicpathwaythalamussomato-sensorycortexSPINOTHALAMICDAMAGEspinothalamicpathwayLeftspinalcordinjuryLossofsenseof:TouchPainWarmth/coldinrightleg2.2DORSALCOLUMNPATHWAYCarriesfinetouch,vibrationandconsciousproprioceptionsignals1stneuronentersspinalcordthroughdorsalroot;ascendstomedulla(brainstem)2ndneuroncrossesoverinmedulla;ascendstothalamus3rdneuronprojectstosomatosensorycortex三者的傳入沖動↓經后根節外側部(粗纖維部分)↓進入脊髓后角↓沿同側后索上行↓抵達延髓下部在薄束核、楔束核換神經元↓換元后的第Ⅱ級神經元發出纖維↓交叉到對側↓沿內側丘系↓到達丘腦感覺接替核。DorsalcolumnpathwayLargesensorynerves:Touch,vibration,two-pointdiscrimination,proprioceptionPrimarysomatosensorycortex(S1)inparietallobeThalamusMedullaMediallemniscusSpinalcordDorsalcolumnDorsalcolumnnucleiTWO-POINTDISCRIMINATIONSENSORYMODALITYFigure10-3:Two-pointdiscriminationDORSALCOLUMNDAMAGEdorsalcolumnpathwayLeftspinalcordinjuryLossofsenseof:touchproprioceptionvibrationinleftlegDORSALCOLUMNDAMAGESensoryataxiaPatientstaggers;cannotperceivepositionormovementoflegsVisualclueshelpmovementSENSORYSYNDROMES1.Peripheralnerve: accordingtothedistributionareaoftheaffectednervePolyneuropathy: glove–stockingdistribution, morepronaunceddistaly,moreonthelowerextremitiesDorsalrootgangliaorradicularlaesions: segmental,localisedtodermatomesSENSORYSYNDROMES2.Spinalcord: -completecordlesion -hemisectionofspinalcord:Brown–Sequardsyndrome -centralcordlesion(Syringomyelia,dissociatedsensoryloss:lossofpainandtemperature,preservationofproprioception) -posteriortractlesion(funicularmyelosis:lossofproprioception,ataxia) -conuslaesion(sensorylossofsacralarea,“saddleanaesthesia)Brainstem:WallenbergsyndromeThalamus:Dejerine–Roussysyndrome(contralateralhemihypaesthesia,ataxia,pain)Sensorycortex:contralateralhemihypa