ventricular anatomy and csf physiology

Anatomy of the Ventricles Anatomy of the Ventricles and CSF Physiologyand CSF Physiology

Dr F TalebDr F Taleb

Ventricles of the BrainVentricles of the Brain

CNS is hollowCNS is hollow Develops from a NEURAL TUBE whose Develops from a NEURAL TUBE whose

cavity persistscavity persists Lined with single Epithelial-like layer of Lined with single Epithelial-like layer of

cells – Ependyma (cuboidal)cells – Ependyma (cuboidal) VentriclesVentricles


Ventricles contain CSFVentricles contain CSF Secreted in ventricles by choroid plexusSecreted in ventricles by choroid plexus CSF necessary for brain development – CSF necessary for brain development –

Reasons ??Reasons ??


Normal brain- 4 Normal brain- 4 ventriclesventricles

2 lateral - Cerebal 2 lateral - Cerebal hemisphereshemispheres

33rdrd ventricle – ventricle – DiencephalonDiencephalon

44thth Pons and Medulla- Pons and Medulla- sharing sharing

connnections – FOM connnections – FOM and ASand AS


Lateral ventriclesLateral ventricles C shaped structure C shaped structure Around the caudate Around the caudate

nucleus and white nucleus and white matter of the internal matter of the internal capsulecapsule


Lateral VentriclesLateral Ventricles 5 Parts5 Parts Frontal(anterior) HornFrontal(anterior) Horn BodyBody Atrium(Trigone) Atrium(Trigone) Occipital(posterior)Occipital(posterior) Temporal(inferior)Temporal(inferior)


Frontal HornFrontal Horn Anterior to Foramen Anterior to Foramen

of Monroof Monro Corpus Callosum – Corpus Callosum –

roof, anterior part and roof, anterior part and part of the floorpart of the floor

Bulbous head of the Bulbous head of the caudate nucleus caudate nucleus forms the rest of the forms the rest of the floorfloor


Lateral wall – Lateral wall – Caudate nucleusCaudate nucleus

Meets the roof at an Meets the roof at an angleangle

Medial wall – septum Medial wall – septum pellucidum- (4 layers pellucidum- (4 layers 2 pia 2 ependyma) 2 pia 2 ependyma) and anterior column and anterior column of fornixof fornix

No choroid plexusNo choroid plexus


BODYBODY BehindBehind FOM FOM Floor – Thalamus and Floor – Thalamus and

body of the caudate body of the caudate nucleusnucleus

Grove – Grove – thalamostriate vein thalamostriate vein and Stria medullaris and Stria medullaris (amygdala to ant perf subs)(amygdala to ant perf subs)


Roof - Corpus Roof - Corpus CallosumCallosum

Medial wall – crus Medial wall – crus and body of the fornixand body of the fornix

Choroid plexus Choroid plexus invaginates between invaginates between thalamus and fornix – thalamus and fornix – choroid fisssurechoroid fisssure

Covered with 2 layers Covered with 2 layers –pia and ependyma–pia and ependyma


Lateral wall –Lateral wall –essentially caudate essentially caudate body body

Note: the genu of the Note: the genu of the internal capsule internal capsule touches the lateral touches the lateral wall lateral to FoM wall lateral to FoM between tha caudate between tha caudate and thalamusand thalamus


Cavity arches Cavity arches downwards and downwards and forwards into the forwards into the Temporal horn and Temporal horn and backwards into the backwards into the occipital hornoccipital horn

Atrium/trigoneAtrium/trigone


Occipital HornOccipital Horn Most variable Most variable Can be absentCan be absent Floor: collateral Floor: collateral

eminence – collateral eminence – collateral sulcussulcus

Medial wall: 2 Medial wall: 2 convexitiesconvexities

Upper – bulb – fibres Upper – bulb – fibres of forceps majorof forceps major


Lower - calca avis – Lower - calca avis – calcarine sulcuscalcarine sulcus

Can obliterate the Can obliterate the occiptal horn when occiptal horn when well developedwell developed

Roof - tapetum of Roof - tapetum of corpus callosumcorpus callosum

Lateral wall – optic Lateral wall – optic radiationradiation

NO choroid plexusNO choroid plexus


Temporal HornTemporal Horn ?? Largest Largest Medial part of Medial part of

temporal lobetemporal lobe Ends blindly posterior Ends blindly posterior

to amygdaloid bodyto amygdaloid body


Floor –Floor – Hipppocampus Hipppocampus

mediallymedially Collateral eminence Collateral eminence

laterallylaterally


Roof – Roof – Tail of caudate Tail of caudate

continuous anteriorly continuous anteriorly with the amygdaloid with the amygdaloid boby – lateral to boby – lateral to anterior perforated anterior perforated substancesubstance

Prominence at tip Prominence at tip above pes hippoabove pes hippo

Laterally tapetumLaterally tapetum


Lateral wall – Lateral wall – TapetumTapetum


Medially –Medially – Choroid fissureChoroid fissure Lower lip - fimbria Lower lip - fimbria Upper lip – tail of Upper lip – tail of

caudatecaudate


TrigoneTrigone Body - temporal - Body - temporal -

occipital horns occipital horns convergeconverge

Base on pulvinar Base on pulvinar Glomus – tuft of Glomus – tuft of

choroid plexus choroid plexus Calcified Calcified


THIRD VENTRICLETHIRD VENTRICLE Slit likeSlit like space in space in

sagital planesagital plane Lateral wall - Lateral wall -

thalamus mainlythalamus mainly


Thalamus bulge of Thalamus bulge of grey matter grey matter

Interthalamic Interthalamic adhesion(massa adhesion(massa intermedia) in 60% of intermedia) in 60% of brains onlybrains only

Not a comissureNot a comissure


Hypothalamic grove - Hypothalamic grove - from FoM to ASfrom FoM to AS

Hypothalamus - Hypothalamus - below grove including below grove including floorfloor

Subthalamus caudally Subthalamus caudally merges with midbrainmerges with midbrain

Hypothalamus – Hypothalamus – supraoptic and supraoptic and paraventricular nucleiparaventricular nuclei


Stria meditullaris – Stria meditullaris – runs along runs along superomedial border superomedial border of thalamusof thalamus

White matter band White matter band from piriform area from piriform area

U loop posteriorly - U loop posteriorly - habenular comissurehabenular comissure

Olfactory(like ant Olfactory(like ant commissure) commissure)


Columns of fornix – Columns of fornix – prominence from FoM prominence from FoM blends in the lateral blends in the lateral wall wall


Roof – Roof – From FoM to supra From FoM to supra

pineal recesspineal recess 4 layers4 layers Fornix bodyFornix body 2 layers of pia( tela 2 layers of pia( tela

choroida)choroida) Vascular layer Vascular layer

between the tela between the tela (velum (velum

iinterpositumnterpositum))

Habenular comm.Habenular comm.


Choroid plexus Choroid plexus hanging from roof in hanging from roof in pairspairs

Continuous with Continuous with choroid plexus of choroid plexus of lateral ventricles lateral ventricles through FoM and through FoM and temporal horns(e-temporal horns(e-shaped)shaped)


Anterior wall – Anterior wall – Optic chiasm to FoMOptic chiasm to FoM Optic chiasmOptic chiasm Supra optic recessSupra optic recess Lamina terminalisLamina terminalis Anterior commissureAnterior commissure Columns of fornixColumns of fornix


Floor – Floor – From Optic chiasm to From Optic chiasm to

ASAS Ant ½ diencephalicAnt ½ diencephalic Post ½ Post ½

mesencephalicmesencephalic


Ant – postAnt – post Optic chiasmOptic chiasm InfundibulumInfundibulum Tuber Tuber

cinereum(grey)– cinereum(grey)– median eminence – median eminence – no blood/brain barrierno blood/brain barrier

Mamillary bodies Mamillary bodies (external)(external)

Posterior perforated Posterior perforated substancesubstance


Floor -Floor - TegmentumTegmentum ASAS

Ventricles of the BrainVentricles of the Brain Posterior wallPosterior wall From supra pineal From supra pineal

recess to ASrecess to AS Superior – inferiorSuperior – inferior Supra pineal recess – Supra pineal recess –

slack roof pia + slack roof pia + ependymaependyma

Habenular comm.Habenular comm. Pineal body and Pineal body and

recessrecess Posterior comm. -Sup Posterior comm. -Sup

colliculicolliculi


ASAS Through midbrainThrough midbrain Into 4Into 4thth ventricle ventricle


FOURTH FOURTH VENTRICLEVENTRICLE

Extends from the AS Extends from the AS to the central canalto the central canal

Rhomboid shaped Rhomboid shaped cavity over pons and cavity over pons and medullamedulla

Roof is tent shapedRoof is tent shaped Mainly ependymaMainly ependyma


Covered by the Covered by the cerebellumcerebellum

Upper part – over Upper part – over pons – thin sheet of pons – thin sheet of white matter – white matter – superior medullary superior medullary velumvelum

Bounded by superior Bounded by superior cerebellar pedunclescerebellar peduncles

Ventricles of the BrainVentricles of the Brain Lower part – over Lower part – over

medulla medulla Superiorly Superiorly Ependyma + white Ependyma + white

matter from base of matter from base of flocculus –Inferior flocculus –Inferior medullllary velummedullllary velum

Inferiorly Inferiorly Only ependyma and Only ependyma and

piapia Attached to margins Attached to margins

of cuneate and gacile of cuneate and gacile nucleinuclei


Midline slit Foramen Midline slit Foramen of Magendieof Magendie

Comunicates with Comunicates with cerebellomedullary cerebellomedullary cisterncistern


Lateral recess – Lateral recess – laterallylaterally

Around and behind Around and behind the inferior cerebellar the inferior cerebellar pedunclepeduncle

Narrow and tubularNarrow and tubular Opening – lateral Opening – lateral

aperture-foramen of aperture-foramen of LuschkaLuschka


Opens anteriorly just Opens anteriorly just behind the VIII nervebehind the VIII nerve

Into pontine cisternInto pontine cistern These are the only These are the only

exits from the exits from the ventriclesventricles


Choroid plexus is Choroid plexus is separateseparate

Small L – shapedSmall L – shaped Indents the medullary Indents the medullary

part of the roofpart of the roof Starts at the lateral Starts at the lateral

aperture from a aperture from a branch of PICAbranch of PICA

Lies below flocculusLies below flocculus


Passes medially Passes medially Meets the opposite Meets the opposite

choroid plexuschoroid plexus Run down as parallel Run down as parallel

structures to foramen structures to foramen of Magendie of Magendie

Drains into occipital Drains into occipital sinus sinus


The FloorThe Floor Diamond shaped – Diamond shaped –

Rhomboid fossaRhomboid fossa Upper boundaries – Upper boundaries –

superior and inferior superior and inferior cerebellar pedunclescerebellar peduncles

Lower boundaries – Lower boundaries – gracile and cuneate gracile and cuneate nucleusnucleus


Median sulcus – deep Median sulcus – deep grove from AS to grove from AS to central canalcentral canal

Floor symetrical on Floor symetrical on each sideeach side

Medullary striae – Medullary striae – crosses the floor at its crosses the floor at its widest part aberrant widest part aberrant fibres from pontine fibres from pontine nuclei to cerebellum nuclei to cerebellum via inferior pedunclevia inferior peduncle


Demarcates Demarcates medullary and pontine medullary and pontine partsparts

Overly vestibular area Overly vestibular area at lateral angle at lateral angle


Pontine PartPontine Part Vestibular areaVestibular area Median eminence Median eminence

insignificantinsignificant Lower part – bulge – Lower part – bulge –

Facial collliculusFacial collliculus Overly the recurving Overly the recurving

fibres of CN VII and fibres of CN VII and the underlying CN VI the underlying CN VI nucleusnucleus


Superior fovea – Superior fovea – between vestibular between vestibular area and facial area and facial colliculuscolliculus

Locus caerulus – Locus caerulus – bluish colour due to bluish colour due to noradrenergic noradrenergic pigmented cells – part pigmented cells – part of Reticular Formationof Reticular Formation


Medullary partMedullary part Smaller than Pontine Smaller than Pontine

partpart Vestibular areaVestibular area Inferior fovea divides Inferior fovea divides

the floor into 2 smaller the floor into 2 smaller trainglestraingles

Superior triangle – Superior triangle – hypoglossal triangle hypoglossal triangle CN XII nucleusCN XII nucleus


Inferior/lateral triangle Inferior/lateral triangle – Vagal triangle– Vagal triangle

CSF PhysiologyCSF Physiology

Entire CNS cavity –Entire CNS cavity –Brain and spine 1600 Brain and spine 1600 to1700mlto1700ml

150ml CSF150ml CSF VentriclesVentricles CisternsCisterns Subarachnoid space Subarachnoid space

– brain and cord– brain and cord All connected and All connected and

pressure regulated pressure regulated


FormationFormation 500 ml/day – 3 to 4 times total vol500 ml/day – 3 to 4 times total vol 2/3 from choroid plexuses2/3 from choroid plexuses Rest mostly from ependymal surfaces and Rest mostly from ependymal surfaces and

arachnoidal membranesarachnoidal membranes Small amount from brain itself, through the Small amount from brain itself, through the

perivascular spacesperivascular spaces Outflow – arachnoid villi in the venous Outflow – arachnoid villi in the venous

sinusessinuses


Secretion by the Choroid PlexusSecretion by the Choroid Plexus Depends on active transport of sodium Depends on active transport of sodium

ions through the epithelial cells that line ions through the epithelial cells that line the plexusthe plexus

Chloride followsChloride follows Water follows by osmosisWater follows by osmosis Also small amount of glucose is pumped Also small amount of glucose is pumped

out and potassium and bicarbonate into out and potassium and bicarbonate into the capillariesthe capillaries


CSF –CSF – Osmotic pressure =plasmaOsmotic pressure =plasma Sodium conc = plasmaSodium conc = plasma Cl 15% > plasmaCl 15% > plasma K 40% < plasmaK 40% < plasma Glucose 30%< plasmaGlucose 30%< plasma


AbsorptionAbsorption Arachnoid villi – Arachnoid villi –

microscopic fingerlike microscopic fingerlike projections of the projections of the arachnoid membrane arachnoid membrane into the venous into the venous sinusessinuses

Conglomerates – Conglomerates – macroscopic macroscopic arachnoid arachnoid granulationsgranulations

CSF physiologyCSF physiology

Endothelial cells - Large holes through the Endothelial cells - Large holes through the bodies of the cellbodies of the cell

Free flow of prot red and white cells into Free flow of prot red and white cells into venous sinusvenous sinus

Some absorbtion around the spinal nerve Some absorbtion around the spinal nerve rootsroots


Perivascular spacesPerivascular spaces Blood vessels Blood vessels

penetrate the brain penetrate the brain parenchyma carying a parenchyma carying a layer of pia materlayer of pia mater

Loosely packed Loosely packed around – perivascular around – perivascular spacespace

Up to arterioles and Up to arterioles and venulesvenules

Not capillariesNot capillaries


Lymphatic Funtion of Perivascular SpaceLymphatic Funtion of Perivascular Space No lymphatics in brainNo lymphatics in brain Protein leaks into brain tissueProtein leaks into brain tissue Leaves brain tissue into perivasc spaces Leaves brain tissue into perivasc spaces

then subarachnoid spacethen subarachnoid space Thus the protein is scavenged into the Thus the protein is scavenged into the

CSF.CSF. Also removes debris – dead white cells etcAlso removes debris – dead white cells etc


CSF pressureCSF pressure Normal 13 mm Hg – lying down(5 – 20 mmHg)Normal 13 mm Hg – lying down(5 – 20 mmHg) Regulation of pressure by absorption by the Regulation of pressure by absorption by the

arachnoid villi mainlyarachnoid villi mainly Production is fairly constantProduction is fairly constant Villi functions as valvesVilli functions as valves No back flow of bloodNo back flow of blood ‘‘Opening pressure’ of 1.5mmHgOpening pressure’ of 1.5mmHg


Blood / fibrosis / particles / proteins can Blood / fibrosis / particles / proteins can block the villiblock the villi

Also mechanical blockage around incisuraAlso mechanical blockage around incisura HydrocephalusHydrocephalus


Blood-brain barrier and blood-CSF barrierBlood-brain barrier and blood-CSF barrier CSF and brain interstitial fluid differentCSF and brain interstitial fluid different Tight junctions – only selective diffusionTight junctions – only selective diffusion Permeable to water, carbon dioxide, Permeable to water, carbon dioxide,

oxygen, and most lipid soluble oxygen, and most lipid soluble substances(alcohol and anaesthetic substances(alcohol and anaesthetic drugs)drugs)

Slightly permeable to electrolytesSlightly permeable to electrolytes Impermeable to protein and hydrophillicsImpermeable to protein and hydrophillics


Pia and ependyma are permeablePia and ependyma are permeable Most substances in the CSF can diffuse Most substances in the CSF can diffuse

into the brain parenchymainto the brain parenchyma Drugs that do not cross the blood-brain Drugs that do not cross the blood-brain

barrier can be injected intrathecallybarrier can be injected intrathecally


Mechanical CushioningMechanical Cushioning Major function of CSF !Major function of CSF ! Brain and CSF have the same SG(4%diff)Brain and CSF have the same SG(4%diff) Brain is ‘suspended’ in the vaultBrain is ‘suspended’ in the vault A blow to the head moves the entire brain A blow to the head moves the entire brain

simultaneouslysimultaneously

CSF PhysiologyCSF Physiology ContrecoupContrecoup Severe blow – cause damage on the opposite Severe blow – cause damage on the opposite

sideside How? Rapid acceleration and deccelrationHow? Rapid acceleration and deccelration Due to inertiaDue to inertia On the initial mvt the brain is cushioned On the initial mvt the brain is cushioned

(momentum is diffused) by the CSF – crumple (momentum is diffused) by the CSF – crumple zonezone

Due to the inertia relative CSF deficiency at Due to the inertia relative CSF deficiency at opposite end.opposite end.

On decceleration brain hits vault with no CSF On decceleration brain hits vault with no CSF cushion – No crumple zone - CONTUSIONcushion – No crumple zone - CONTUSION

ventricular anatomy and csf physiology

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