Gross Brain Overview: Part II Gross Brain Overview: Part II

Basic NeuroscienceBasic Neuroscience

James H. Baños, Ph.D.James H. Baños, Ph.D.

OverviewOverview

OrganizationOrganization Morphology Morphology Developmental/EvolutionaryDevelopmental/Evolutionary CytoarchitecturalCytoarchitectural

3-D Orientation to Internal 3-D Orientation to Internal StructuresStructures

How do we organize and characterize different How do we organize and characterize different parts of the brain?parts of the brain?

How do we organize and characterize different How do we organize and characterize different parts of the brain?parts of the brain? Morphology Morphology Developmental/Evolutionary OriginsDevelopmental/Evolutionary Origins CytoarchitectureCytoarchitecture FunctionFunction

Morphology: Morphology: External FeaturesExternal Features

Frog

Rat

Cat

MonkeyHuman

What’s changing?

Sulci - The “valleys” on the surface Sulci - The “valleys” on the surface of the brainof the brain

Gyri - The “Hills”Gyri - The “Hills”

The term “gyrus” is sometimes used broadly and doesn’t alwaysrefer to a single well-defined ridge on the surface of the brain.The distinctions between large gyri are sometimes better seen incoronal sections.

HemispheresHemispheres

LongitudinalFissure

LobesLobes

Central (Rolandic) Sulcus

Lateral (Sylvian) fissure

Parieto-occipital fissure

LobesLobes

Frontal

Parietal

Temporal

Occipital

Cingulate Gyrus“Limbic Lobe”

Brain StemBrain Stem

Thalamus

Hypothalamus

Midbrain

Pons

Medulla

Cerebellum: Superior Cerebellum: Superior AspectAspect

Ant

2 Hemispheres2 Hemispheres VermisVermis

Cerebellum: Posterior Cerebellum: Posterior AspectAspect

Hemisphere HemisphereVermis

Posterior Lobe

Anterior Lobe

Primary Fissure

Cerebellum: Mid-Cerebellum: Mid-SaggitalSaggital

Anterior Vermis

Posterior Vermis

Developmental and Developmental and Evolutionary Origins: Evolutionary Origins:

The “Cephalons”The “Cephalons”

Developmental OriginsDevelopmental Origins Areas of the Brain can be Areas of the Brain can be

characterized by the characterized by the embryonic origins of the embryonic origins of the tissue.tissue.

Nervous system begins as Nervous system begins as a tube that differentiates a tube that differentiates into three vessicles:into three vessicles: ProsencephalonProsencephalon MesencephalonMesencephalon RhombencephalonRhombencephalon

Three Vessicle Stage

Developmental OriginsDevelopmental Origins Prosencephalon Prosencephalon

differentiates:differentiates: Telencephalon -- beginnings Telencephalon -- beginnings

of hemispheresof hemispheres DiencephalonDiencephalon

Rhombencehphalon Rhombencehphalon differentiatesdifferentiates MetencephalonMetencephalon MeyelencephalonMeyelencephalon

We use this terminology to We use this terminology to describe the parts of the describe the parts of the brain that develop from brain that develop from these vessiclesthese vessicles

Five Vessicle Stage

Developmental OriginsDevelopmental Origins

Cerebral CortexBasal GangliaLimbic SystemHippocampus

Telencephalon(endbrain)

ThalamusHypothalamus

Diencephalon(interbrain)

Prosencephalon(forebrain)

Midbrain

Mesencephalon

Mesencephalon

CerebellumPons

Metencephalon

Medulla

Myelencephalon

Rhombencephalon(hindbrain)

OrganizationOrganization

TelencephalonTelencephalon CortexCortex Basal GangliaBasal Ganglia Limbic SystemLimbic System HippocampusHippocampus

OrganizationOrganization

DiencephalonDiencephalon ThalamusThalamus HypothalamusHypothalamus

OrganizationOrganization

MesencephalonMesencephalon MidbrainMidbrain

OrganizationOrganization

MetencephalonMetencephalon CerebellumCerebellum PonsPons

OrganizationOrganization

MyelencephalonMyelencephalon MedullaMedulla

Cytoarchitectural Cytoarchitectural OrganizationOrganization

Brodmann’s AreasBrodmann’s Areas

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Internal Internal StructureStructure

Major Internal Major Internal StructuresStructures

Ventricular SystemVentricular System Amygdala (helpful landmark)Amygdala (helpful landmark) Thalamus/Hypothalamus/brain stemThalamus/Hypothalamus/brain stem Basal GangliaBasal Ganglia

Caudate NucleusCaudate Nucleus PutamenPutamen Globus PallidusGlobus Pallidus

Hippocampal formationHippocampal formation HippocampusHippocampus FimbriaFimbria FornixFornix

Major white matter landmarksMajor white matter landmarks Corpus callosumCorpus callosum Internal capsuleInternal capsule

Evolution and Evolution and DevelopmentDevelopment

Frog

Rat

Cat

MonkeyHuman

Evolution and Evolution and DevelopmentDevelopment

Frog

Rat

Cat

MonkeyHuman

?

Evolution and Evolution and DevelopmentDevelopment

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Ventricles

Basal Ganglia

Hippocampus

Evolution and Evolution and DevelopmentDevelopment

Why not the thalamus?

The Ventricular The Ventricular SystemSystem

VentriclesVentricles

Lateral Ventricles

Third Ventricle

Fourth Ventricle

VentriclesVentricles

Ventricles are connected (communicate)Ventricles are connected (communicate) Intraventricular Foramina (of Monroe)Intraventricular Foramina (of Monroe)

Lateral Ventricles to Third VentricleLateral Ventricles to Third Ventricle Wide, oval holeWide, oval hole

Cerebral Aqueduct (of Sylvius)Cerebral Aqueduct (of Sylvius) Third Ventricle to FourthThird Ventricle to Fourth Long, thin channelLong, thin channel

Foramen of MagendieForamen of Magendie Median aperture -- Fourth ventricle to subarachnoid spaceMedian aperture -- Fourth ventricle to subarachnoid space

Foramina of LuschkaForamina of Luschka Lateral apertures -- Fourth ventricle to subarachnoid Lateral apertures -- Fourth ventricle to subarachnoid

spacespace

VentriclesVentricles

Foramen of Monroe

Aqueduct of Sylvius

Foramina of Luschka

Foramen of Magendie

VentriclesVentricles

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VentriclesVentricles

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VentriclesVentricles

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VentriclesVentricles

Choroid Plexus and CSFChoroid Plexus and CSF

Choroid PlexusChoroid Plexus Spongy tissue located in the ventriclesSpongy tissue located in the ventricles Rich capillary bedRich capillary bed Pia MaterPia Mater Choroid endothelial cellsChoroid endothelial cells

Produces CSFProduces CSF About .35 ml per minuteAbout .35 ml per minute Total volume 70-120 mlTotal volume 70-120 ml

Choroid PlexusChoroid Plexus

CSF FlowCSF Flow Lateral ventriclesLateral ventricles Foramina of MonroeForamina of Monroe 3rd ventricle3rd ventricle Aqueduct of SylviusAqueduct of Sylvius 4th Ventricle4th Ventricle Foramen of Magendie/foramina of LushkaForamen of Magendie/foramina of Lushka Subarachnoid SpaceSubarachnoid Space Arachnoid granulations (absorption)Arachnoid granulations (absorption) Superior sagittal sinusSuperior sagittal sinus

CSF FlowCSF Flow

CSF AbsorptionCSF Absorption

CSF flows to the dorsal surface of CSF flows to the dorsal surface of the brain, where the brain, where arachnoid arachnoid granulations granulations form a one-way valve form a one-way valve and let the excess CSF enter the and let the excess CSF enter the veinous drainage of the superior veinous drainage of the superior sagittal sinussagittal sinus

CSF AbsorptionCSF Absorption

Arachnoid GranulationsArachnoid Granulations

Ventricular System plus AmygdalaVentricular System plus Amygdala

Ventricular System plus ThalamusVentricular System plus Thalamus

Ventricular System plus ThalamusVentricular System plus Thalamus

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Ventricles, Brainstem, and Ventricles, Brainstem, and ThalamusThalamus

Ventricles, Brainstem, and Ventricles, Brainstem, and ThalamusThalamus

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Basal Ganglia -- Caudate NucleusBasal Ganglia -- Caudate Nucleus

Basal GangliaBasal Ganglia Caudate NucleusCaudate Nucleus PutamenPutamen Globus PallidusGlobus Pallidus Sometimes Sometimes

AmygdalaAmygdala

Basal Ganglia -- Caudate NucleusBasal Ganglia -- Caudate Nucleus

Basal Ganglia -- Caudate NucleusBasal Ganglia -- Caudate Nucleus

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Basal Ganglia -- Caudate NucleusBasal Ganglia -- Caudate Nucleus

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Basal Ganglia -- Putamen & Basal Ganglia -- Putamen & Globus PallidusGlobus Pallidus

Basal Ganglia -- Putamen & Basal Ganglia -- Putamen & Globus PallidusGlobus Pallidus

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Basal GangliaBasal Ganglia

Basal GangliaBasal Ganglia

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Basal GangliaBasal Ganglia

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Internal CapsuleInternal Capsule

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HippocampusHippocampus

Hippocampal Hippocampal formationformation

FimbriaFimbria FornixFornix Anterior Anterior

CommissureCommissure AmygdalaAmygdala

HippocampusHippocampus

HippocampusHippocampus

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Coming up…Coming up…

Spinal cordSpinal cord Basic Spinal PathwaysBasic Spinal Pathways