感觉系统症状

感觉神经系统症状GeneralPropertiesofSensorySystemsFigure10-4:Sensorypathways1.SensoryreceptorsA:Freenerveendings(pain,temperature)B:Paciniancorpuscle(pressure)C:Meissner’scorpuscle(touch)D:Musclespindle(stretch)ABCDSensoryReceptorTypesFigure10-1:SensoryreceptorsRuffini'sendingsrespondtotensionandstretchintheskin

Segmentalinnervation(dermatomes)

Peripheralinnervation

感觉传导路由三级神经元组成：第Ⅰ级神经元:胞体位于脊髓后根神经节或脑神经感觉神经节

第Ⅱ级神经元:胞体位于脊髓后角细胞及延髓薄束核、楔束核或脑干脑神经核

第Ⅲ级神经元:胞体位于丘脑感觉接替核SpinothalamicpathwayCarriespain,temperature,touchandpressuresignals1stneuronentersspinalcordthroughdorsalroot2ndneuroncrossesoverinspinalcord;ascendstothalamus3rdneuronprojectsfromthalamustosomatosensorycortex2.浅感觉传导路:前外侧系统theanterolateralsystem

(先交叉，后上行)轻触-压觉,痛觉,温度觉的传入纤维↓经后根节外侧部(细纤维部分)↓进入脊髓后角并于此换元↓换元后的第Ⅱ级神经元发出纤维↓在中央管前交叉到对侧↓沿脊髓丘脑前束、脊髓丘脑侧束↓上行到达丘脑感觉接替核SomaticPathwaysFigure10-9:Sensorypathwayscrossthebody’smidlineSpinothalamicPathwaySmallsensoryfibres:Pain,temperature,sometouchPrimarysomatosensorycortex(S1)ThalamusMedullaSpinalcordSpinothalamictractImpulsestransmittedtospinalcordbyMyelinatedAδnerves:fastpain(80m/s)UnmyelinatedCnerves:slowpain(0.4m/s)nociceptornociceptorAδnerveCnervespinothalamicpathwaytoreticularformationImpulsesascendtosomatosensorycortexvia:Spinothalamicpathway(fastpain)Reticularformation(slowpain)reticularformationspinothalamicpathwaythalamussomato-sensorycortexSpinothalamicdamagespinothalamicpathwayLeftspinalcordinjuryLossofsenseof:TouchPainWarmth/coldinrightleg请同学们屈起右腿右手放在桌子上闭上眼睛按指令完成动作2.2DorsalcolumnpathwayCarriesfinetouch,vibrationandconsciousproprioceptionsignals1stneuronentersspinalcordthroughdorsalroot;ascendstomedulla(brainstem)2ndneuroncrossesoverinmedulla;ascendstothalamus3rdneuronprojectstosomatosensorycortex三者的传入冲动↓经后根节外侧部(粗纤维部分)↓进入脊髓后角↓沿同侧后索上行↓抵达延髓下部在薄束核、楔束核换神经元↓换元后的第Ⅱ级神经元发出纤维↓交叉到对侧↓沿内侧丘系↓到达丘脑感觉接替核。dorsalcloumnpathwayDorsalcolumnpathwayLargesensorynerves:Touch,vibration,two-pointdiscrimination,proprioceptionPrimarysomatosensorycortex(S1)inparietallobeThalamusMedullaMediallemniscusSpinalcordDorsalcolumnDorsalcolumnnucleiTwo-PointDiscriminationSensoryModalityFigure10-3:Two-pointdiscriminationSensoryModalityFigure10-6:LateralinhibitionDorsalcolumndamagedorsalcolumnpathwayLeftspinalcordinjuryLossofsenseof:touchproprioceptionvibrationinleftlegDorsalcolumndamageSensoryataxiaPatientstaggers;cannotperceivepositionormovementoflegsVisualclueshelpmovement由于传导痛觉、温度觉的传入纤维在进入脊髓后→在进入水平的1-2个节段内更换神经元并交叉到对侧；而传导轻触(-压)觉的传入纤维在进入脊髓后分成上行和下行纤维，分别在多个节段内更换神经元并交叉到对侧，因而发生上述痛、温觉受损而触觉保留现象。3.头面部的感觉传导路：

Facialsensorypathway

触觉、本体感觉的传入冲动↓三叉神经主核、中脑核中继换元痛觉、温度觉的传入冲动↓三叉神经脊束核中继换元发出第Ⅱ级纤维→越至对侧→三叉丘系→丘脑后内侧腹核Sensorysyndromes1.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,pa