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CLINICAL NEURO- ANATOMY MeghanMinnis 1 Cerebralhemispheres Intended 2 Visualpathway Learning 3 Diencephalon Outcomes: 4 Spinalcord Describethestructureofthe 5 Caudaequina nervoussystemandgive examplesofwhatclinicalsigns 6 Nerveroots mightbeseenwithlesionsatthe followinglevels: 7 Brachialplexus 8 LumbarplexusCEREBRUMCEREBRUM SULCI + GYRI Sulcus: from latin for 'furrow'. Gyrus: from latin for circle.FRONTAL LOBEFRONTAL LOBE (Superiorfrontalgyrus,middlefrontal PrefrontalCortex gyrusandinferiorfrontalgyrus)eypathologies: ADHD Managementofhighercognitivefunctions Stroke suchasplanning,organizing,motivation, Frontotemporaldementia discipline,problem-solving,self-controland Resultsinpersonalitychange,problemswith emotionalregulation. memoryandexecutivefunctioning. MotorCortex Precentralgyrus Keypathologies: Causesuppermotorneurone Controlofvoluntarymovement,spatialorientation Stroke signsonthecontralateral Trauma sideofthebody. Keypathologies: Broca'sArea (Dominanthemisphere) Broca'saphasia:non-fluentaphasia, Speechproduction expressiveasabletounderstand languagebutdifficultyproducingitPARIETAL LOBEPARIETAL LOBE Post-centralgyrus Keypathologies: Somatosensorycortex Stroke Receivesinformationfromtheascendingspinal tracts(spinothalamic,DCML)-somatotopic. Impairedsensationoncontralateralsideofbody. Keypathologies: ParietalAssociationCortex Stroke Dominantside:languageandcalculation Non-dominantside:visuospatialfunctions. Dominantside:hemispatialneglect Non-dominantside:apraxia,agnosia Dorsalopticradiation Keypathologies: Carriesinformationfromtheinferiorpartofthe Stroke Contralaterallowerquadrantanopia. visualfield.TEMPORAL LOBETEMPORAL LOBE Hippocampusandamygdala Keypathologies: MedialTemporalLobe Emotionandmemory. Epilepsy(focal) Alzheimer'sdisease Keypathologies: AuditoryAreas Primary/secondaryauditorycortices:auditory Stroke processing. Auditoryagnosia:patientcannotrecognisebasic Auditoryassociationarea:interpretationof sounds soundsandfortheassociationoftheauditory inputwithothersensoryinformation. Keypathologies: Dominanthemisphere Wernicke'sArea Wernicke'saphasia:receptiveaphasia, Comprehensionofwrittenandspokenlanguage. fluentlyspeaksincorrectornonexistent words.OCCIPITAL LOBEOCCIPITAL LOBE Primaryvisualcortex Keypathologies: Integrationandperceptionofvisualinformation. Stroke Retinotopicarrangement. Corticalblindness(blindnesswithnormal pupillarylightresponses). Visualassociationcortex V2:colour,motion,anddepthperception. V3:linkstoparietalandtemporalprocessing. V4:colours,orientation,formandmovement. Communicateswithtemporallobe.OCCIPITAL LOBE Primaryvisualcortex= Locatedinthecalcarine striatecortex fissureCEREBELLUMCEREBELLUMDIVISIONS AnatomicalLobes: Zones:FUNCTIONAL: Cerebrocerebellum:lateralhemispheres Planningofmovementandsensoryinput. Spinocerebellum:vermisandintermediatezone. Finetuningofaxialandlimbmovements. Vestibulocerebellum:flocculonodularlobe. Involvedinbalanceandspatialorientation.CEREBELLAR SIGNS: D ysdiadochokinesia A taxia N ystagmus I ntentiontremor S canningspeech Cerebellarlesionscauseipsilateralsigns Vermis:truncal/gaitataxia H ypotonia Hemispheres:limbataxiaVISUAL PATHWAYSTHE VISUAL PATHWAY Lateralgeniculatenucleusis partofthethalamus Twoopticradiations: Meyer'sloop-->passes throughtemporallobe, superiorpartofvision Dorsalbundle-->passes throughparietallobe, inferiorpartofvisionVISUAL FIELD DEFECTS Lesiontoopticnerve:lossof sightinoneeyebutcanstill seeentirevisualfield(poor depthperceptionetc) Bitemporalhemianopia: pituitaryadenomaDIENCEPHALONDIENCEPHALON Thalamus: Relay centre for sensory and motor information. Hypothalamus: Release of hormones from anterior pituitary Production of hormones stored in posterior pituitary Regulation of body temperatureBRAINSTEMBRAINSTEMBRAINSTEM Midbrain Cranialnerves: Substantianigra:movement Fibresfromsensoryand IV:Trochlear Inferiorcolliculi:auditory motortracts III:Oculomotor(midbrain-pontinejunction) processing Periaqueductalgreymatter: Rednucleus:motorcoordination painmodulation Pons Cranialnerves: Locuscoerulus:producesNorA V:Trigeminal Fibresfromsensoryandmotortracts Ponto-medullaryjunction: VII:Facial Cranialnervenuclei VI:Abducens VIII:Vestibulocochlear MedullaOblongata Cranialnerves: Pyramids:DCMLpathwaydecussates IX:Glossopharyngeal XI:Accessory Nucleiofsolitarytract:baroreceptorandchemoreceptorinput X:Vagus forbloodpressure,respiratoryreflexes,peristalsis XII:HypoglossalCN EXITING BRAINSTEM Trochlearnerve: OnlyCNthatleavesthebrainstem posteriorly LongestintracranialcourseSPINAL CORDSPINAL CORD ANATOMY AriseabovevertebrauntilC7,fromC8 arisebelow Cervicalenlargement:brachialplexus Lumbarenlargement:lumbarandand sacralplexi SpinalcordendsatL1-2-->cauda equina Nerveroots: Dorsalroot:afferentfibres Ventralroot:efferentfibresSPINAL CORD ANATOMY Epiduralspacefilledwithfat-->no epiduralspaceinbrainSPINAL CORD ANATOMY ArteryofAdamkiewicz: Supplieslower1/3ofspinalcord Usuallyarrisesfromleftposteriorintercostal artery Anteriorspinalarterysyndromeegdueto abdominalaorticaneurysmsurgery: -Urinary/faecalincontinence -Impairedmotorfunctionoflegs/spasticitySPINAL CORD ANATOMYSPINAL CORD ANATOMYSPINAL CORD ANATOMYSPINAL CORD ANATOMYDERMATOMES AND MYOTOMES DermatoMyotomes: SPINAL CORD INJURIES UpperMotorNeuroneSigns LowerMotorNeuroneSigns Damagetobrain/spinalcord. Damagetonerveroot,peripheralnerve,muscle, Increasedtone:spasticityorrigidity Pyramidalweakness NMJ. Musclewasting Upperlimbs:extensorsweakerthan Fasciculations flexors Lowerlimbs:flexorsweakerthan Normalordecreasedtone Hyporeflexiaorareflexia extensors Hyperreflexia(exaggerated/briskreflexes) Facialnerve: UMN:weaknessofinferiorfacialmuscles,withsparingofforehead.Impactofbilateralneuronefromcingulatecortexpresent. LMN:weaknessofsuperiorandinferiorfacialmuscles. SPINAL CORD INJURIES Brown-SequardSyndrome: Hemisectionofcordduetotraumaticinjuryeg stabbing. Paralysisonaffectedside Lossofproprioceptionandfinediscrimination Painandtemperaturelossbelowlesionon contralateralside AnteriorCordSyndrome: Completemotorparalysis Lossofpain/temperature PosteriorCordSyndrome: Proprioception,vibrationandlighttouch affected SPINAL CORD INJURIES CentralCordSyndrome: Occursinolderadultsduetohyperextension.Cordcompressed anteriorlybyosteophytesandposteriorlybyligamentumflavum. MotorsyndromeaffectingupperlimbsmorethanlowerlimbsCAUDA EQUINA ANATOMY NerverootsL1-S5makeupthecaudaequina. Formedbylowermotorneurones: Motorandsensoryimpulsestothelower limbs Motorinnervationtotheanalsphincters Parasympatheticinnervationforthe bladderCAUDA EQUINA SYNDROME Surgicalemergency! Causedbycompressionofthecaudaequina.Mostcommonly duetodisc herniationatL5/S1orL4/L5level.Canbeacuteorchronic. Keyclinicalfeatures: Perianal/saddleanaesthesia Bowel,bladderand/orsexualdysfunction Otherfeaturesincludelowbackpain,sciatica,lowerlimbLMNsigns. Emergencylumbar-sacralspineMRI isthegoldstandard investigation. Management:steroidstoreduceoedemaandrefertoneurosurgeonsfor spinaldecompression.BRACHIAL PLEXUSBRACHIAL PLEXUS BRACHIAL PLEXUS Roots:C5-T1 Trunks:superior,middleandinferior Spinalnervesleavethevertebralcolumnvia Superiortrunk– C5andC6. intervertebralforamina.Divideintoanterior Middletrunk– C7. andposteriorrami. Inferiortrunk– C8andT1. Movelaterallyacrossposteriortriangleof Anteriorrami-formrootsofbrachial neck. plexus Posteriorrami-innervateskinand musclesofintrinsicback Divisions: Passbetweenanteriorandmedialscalene Trunksdivideintotwo:oneposteriorand oneanterior.Leaveposteriortriangleand musclestoenterneck. enteraxilla. BRACHIAL PLEXUS Cords: Majorbranches: Anteriorandposteriordivisionscombineto Musculocutaneousnerve formthreecords.Namedbypositionrelative Axillarynerve toaxillaryartery. Mediannerve Lateral:anteriordivisionsofsuperior Radialnerve andmiddletrunks Ulnarnerve Posterior:posteriordivisionsofall3 Minorbranches: trunks. Medial:anteriordivisionofinferior trunk.BRACHIAL PLEXUS SummarytablefromGeekyMedics. Remember:damagetolongthoracic nervecausesscapularwinging.LUMBAR PLEXUS Anteriorramiof L1-4. Formsixmajor peripheralnerves ofthelumbar plexus:innervate abdominal muscles, genitals,thigh muscles MONONEURITIS MULTIPLEX Commonlyaffectednerves: Commonperoneal:weakankledorsiflexion,sensorydisturbancetolateralaspectofcalf andfoot. Radial:wristandfingerdrop,sensorydisturbancetodorsumofhand Axillary:weaknessofshoulderabduction,sensorydisturbancetolowerdeltoidregion (badge) Median:LOAF(lateraltwolumbricals,opponenspollicis,abductorpollicisbrevis,flexor pollicisbrevisakathumbmuscles)weakness,sensorydisturbance Sciatic:weakhipflexionandkneeextension,sensorydisturbancetolateralaspectofcalf anddorsumoffoot.MCQ'S:A40-year-oldwomanisunsteadyonherfeet.Uponfurtherquestioningshealwaysleansto herrightandhasscrapesonherrightarmfromfallingonthisside.Whenwalkingtothe examinationroomyounoteabroad-basedataxicgait,withapredispositiontoleantothe right. Uponneurologicalexaminationshehasanintentiontremoranddysdiadochokinesiaofher righthand.Herrightlowerlimbisheel-shintestpositive.Lastly,therewasagaze-evoked nystagmusoftherighteye. Whereisthebrainlesionlikelytobe? A:Leftcerebellum D:Rightparietallobe B:Lefttemporallobe E:Righttemporallobe C:RightcerebellumA40-year-oldwomanisunsteadyonherfeet.Uponfurtherquestioningsherevealsshe alwaysleanstoherrightandhasscrapesonherrightarmfromfallingonthisside.When walkingtotheexaminationroomyounoteabroad-basedataxicgait,withapredisposition toleantotheright. Uponneurologicalexaminationshehasanintentiontremoranddysdiadochokinesiaof herrighthand.Herrightlowerlimbisheel-shintestpositive.Lastly,therewasagaze- evokednystagmusoftherighteye. Whereisthebrainlesionlikelytobe? A:Leftcerebellum D:Rightparietallobe B:Lefttemporallobe E:Righttemporallobe C:RightcerebellumA56-year-oldmanpresentstohisGPwithleft-sidedneckpainthatradiatesdownhisarmand'weak fingers'.Healsocomplainsofnumbnessdownthemedialaspectofhisrightarm.Hethinksthisallbegan whenhewasmovinghouse5weeksago. Onexamination,sensationisdiminishedoverthemedialforearmbutisnormalinthehandandfingers. Theonlyotherabnormalitynotedisaweaknessoffingerabduction. Whichnerveroothasbeenaffected? A:T1 D:C7 B:C8 E:C5 C:C6A56-year-oldmanpresentstohisGPwithleft-sidedneckpainthatradiatesdownhisarmand'weak fingers'.Healsocomplainsofnumbnessdownthemedialaspectofhisrightarm.Hethinksthisall beganwhenhewasmovinghouse5weeksago. Onexamination,sensationisdiminishedoverthemedialforearmbutisnormalinthehandandfingers. Theonlyotherabnormalitynotedisaweaknessoffingerabduction. Whichnerveroothasbeenaffected? T1nerverootisreponsiblefor A:T1 D:C7 fingerabduction.Duetoa B:C8 E:C5 thoracicdischerniation. C:C6Theabducensnerve(CNVI)arisesfromwhichpartofthebrainstem? A:Ventralmidbrain B:Dorsalmidbrain C:Immediatelyunderthethalamus D:Dorsalpons E:PontomedullaryjunctionTheabducensnerve(CNVI)arisesfromwhichpartofthebrainstem? A:Ventralmidbrain B:Dorsalmidbrain C:Immediatelyunderthethalamus D:Dorsalpons E:PontomedullaryjunctionA65-year-oldmanisreviewedintheNeurologyClinicfollowingastroke.Manyofhis symptomshaveresolved;however,hereportsthathestillhassomeresidualvisual loss.Visual-fieldtestingrevealsarighthomonymouslowerquadrantanopia. Whereinthevisualpathwayisthelesionmostlikelytobe? A:Leftparietallobe B:Rightparietallobe C:Opticchiasm D:Lateralgeniculatenucleus E:PrimaryvisualcortexA65-year-oldmanisreviewedintheNeurologyClinicfollowingastroke.Manyofhis symptomshaveresolved;however,hereportsthathestillhassomeresidualvisual loss.Visual-fieldtestingrevealsarighthomonymouslowerquadrantanopia. Whereinthevisualpathwayisthelesionmostlikelytobe? A:Leftparietallobe B:Rightparietallobe C:Opticchiasm D:Lateralgeniculatenucleus E:Primaryvisualcortex