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BrainPartI

TheAdultBrain Rangesfrom750ccto2100cc Containsalmost97%ofthebodysneuraltissue Averageweightabout1.4kg(3lb) Regions

Cerebrum Cerebellum Diencephalon

Thalamus Hypothalamus

BrainStem Mesencephalon(Midbrain) Pons Medullaoblongata

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VentriclesoftheBrain VentriclesarelinedwithependymalcellsandcontainCSF Eachcerebralhemispherecontainsonelargelateralventricle Separatedbyathinmedialpartition(septumpellucidum) Thirdventricle

Ventricleofthediencephalon Lateralventriclescommunicate

withthirdventricleviathe

interventricularforamen(foramenofMonro)

Fourthventricle Extendsintomedullaoblongata Becomescontinuouswith

centralcanalofthespinalcord

Connectswiththirdventriclevianarrowcanalin

mesencephalon

TheaqueductofmidbrainTheBrainStem Processesinformationbetween Spinalcordandcerebrumorcerebellum Includes

Mesencephalon(Midbrain) Pons Medullaoblongata

TheBrainStem Mesencephalon

Alsocalledmidbrain Processessight,sound,andassociated

reflexes

Maintainsconsciousness Pons

Connectscerebellumtobrainstem Isinvolvedinsomaticandvisceral

motorcontrol

Medullaoblongata Connectsbraintospinalcord Relaysinformation Regulatesautonomicfunctions:

heartrate,bloodpressure,anddigestion

Diencephalon Locatedundercerebrumand

cerebellum

Linkscerebrumwithbrainstem Thalamus

Relaysandprocessessensoryinformation

Hypothalamus Hormoneproduction Emotion Autonomicfunction

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Pituitarygland Majorendocrinegland Connectedtohypothalamus Viainfundibulum(stalk) Interfacesnervousandendocrinesystems

Cerebellum Secondlargestpartofbrain Coordinatesrepetitivebodymovements Twohemispheres Coveredwithcerebellarcortex

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BrainPartIICerebrum Largestpartofbrain Controlshighermentalfunctions Dividedintoleftandrightcerebralhemispheres Surfacelayerofgraymatter(neuralcortex) Neuralcortex

Alsocalledcerebralcortex Foldedsurfaceincreasessurfacearea Elevatedridges(gyri) Shallowdepressions(sulci) Deepgrooves(fissures)

StructuresoftheCerebrum Gyriofneuralcortex

Increasesurfacearea(numberofcorticalneurons)

Insula(island)ofcortex Liesmedialtolateralsulcus

Longitudinalfissure Separatescerebralhemispheres

Lobes Divisionsofhemispheres

Centralsulcusdivides Anteriorfrontallobefromposteriorparietal

lobe

Lateralsulcusdivides Frontallobefromtemporallobe

Parietooccipitalsulcusdivides Parietallobefromoccipitallobe

ThreeFunctionalPrinciplesoftheCerebrum Eachcerebralhemispherereceivessensory

informationfrom,andsendsmotorcommandsto, the

oppositesideofthebody

Thetwohemisphereshavedifferentfunctions,althoughtheirstructuresarealike

Correspondencebetweenaspecificfunctionandaspecificregionofcerebralcortexisnotprecise

FiberTractsinWhiteMatter Associationfibers

Connectionswithinonehemisphere: Connectonegyrustoanother Connectfrontallobetootherlobesin

samehemisphere

Commissuralfibers Bandsoffibersconnectingtwohemispheres:

Corpuscallosum Anteriorcommissure

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Projectionfibers Passthroughdiencephalon Linkcerebralcortexwithdiencephalon,brain

stem,cerebellum,andspinalcord

TheBasalNuclei Alsocalledcerebralnuclei Massesofgraymatter Areembeddedinwhitematterofcerebrum Involvedwith:

Thesubconsciouscontrolofskeletalmuscletone Thecoordinationoflearnedmovementpatterns(walking,lifting)

Consistsof: Caudatenucleus

Curving,slendertail Lentiformnucleus

Globuspallidus Putamen

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CerebralCortex Thin(24mm)superficiallayerofgraymatter 40%ofthemassofthebrain Siteofconsciousmind:awareness,sensory

perception,voluntarymotorinitiation,

communication,memorystorage,understanding

Eachhemisphereconnectstocontralateralsideofthebody

Thereislateralizationofcorticalfunctioninthehemispheres

FunctionalAreasoftheCerebralCortex Thethreetypesoffunctionalareasare:

Motorareascontrolvoluntarymovement Sensoryareasconsciousawarenessof

sensation

Associationareasintegratediverseinformation

Consciousbehaviorinvolvestheentirecortex

MotorAreas Primary(somatic)motorcortex Premotorcortex Brocasarea FrontaleyefieldPrimaryMotorCortex Allowsconsciouscontrolof

precise,skilled,voluntary

movements

Motorhomunculi:upsidedowncaricatures

representing

the

motorinnervationofbodyregions

PremotorCortex Anteriortotheprecentralgyrus Controlslearned,repetitious,orpatternedmotorskills Coordinatessimultaneousorsequentialactions Involvedintheplanningofmovementsthatdependonsensoryfeedback

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BrocasArea Anteriortotheinferiorregionofthe

premotorarea

Presentinonehemisphere(usuallytheleft)

Amotorspeechareathatdirectsmusclesofthetongue

IsactiveasonepreparestospeakFrontalEyeField Anteriortothepremotorcortexand

superiortoBrocasarea

Controlsvoluntaryeyemovements

SensoryAreas Primarysomatosensorycortex Somatosensoryassociationcortex Visualareas Auditoryareas Olfactorycortex Gustatorycortex Visceralsensoryarea Vestibularcortex

FunctionalBrainSystems Networksofneuronsthatworktogether

andspanwideareasofthebrain

Limbicsystem Reticularformation

LimbicSystem Structuresonthemedialaspectsof

cerebralhemispheresanddiencephalon

Includespartsofthediencephalonandsomecerebralstructuresthatencircle

thebrainstem

Emotionaloraffectivebrain Recognizesangryorfearfulfacialexpressions,assessesdanger,andelicitsthefearresponse Playsaroleinexpressingemotionsviagestures,andresolvesmentalconflict

Putsemotionalresponsestoodors Example:skunkssmellbad

LimbicSystem:EmotionandCognition Thelimbicsysteminteractswiththeprefrontallobes,therefore:

Wecanreactemotionallytothingsweconsciouslyunderstandtobehappening Weareconsciouslyawareofemotionalrichnessinourlives

Hippocampusandamygdalaplayaroleinmemory

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ReticularFormation Threebroadcolumnsalongthelengthofthebrainstem Hasfarflungaxonalconnectionswithhypothalamus,

thalamus,cerebralcortex,cerebellum,andspinalcord

ReticularFormation:RASandMotorFunction RAS(ReticularActivatingSystem)

Sendsimpulsestothecerebralcortextokeepitconsciousandalert

Filtersoutrepetitiveandweakstimuli(~99%ofallstimuli!)

Severeinjuryresultsinpermanentunconsciousness(coma)

Motorfunction Helpscontrolcoarselimbmovements Reticularautonomiccentersregulatevisceralmotor

functions

Vasomotor Cardiac Respiratorycenters