Download - 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 of the BrainVentricles of the Brain
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 ??
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
Lateral VentriclesLateral Ventricles 5 Parts5 Parts Frontal(anterior) HornFrontal(anterior) Horn BodyBody Atrium(Trigone) Atrium(Trigone) Occipital(posterior)Occipital(posterior) Temporal(inferior)Temporal(inferior)
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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)
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
Floor –Floor – Hipppocampus Hipppocampus
mediallymedially Collateral eminence Collateral eminence
laterallylaterally
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
Lateral wall – Lateral wall – TapetumTapetum
Ventricles of the BrainVentricles of the Brain
Medially –Medially – Choroid fissureChoroid fissure Lower lip - fimbria Lower lip - fimbria Upper lip – tail of Upper lip – tail of
caudatecaudate
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
THIRD VENTRICLETHIRD VENTRICLE Slit likeSlit like space in space in
sagital planesagital plane Lateral wall - Lateral wall -
thalamus mainlythalamus mainly
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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)
Ventricles of the BrainVentricles of the Brain
Columns of fornix – Columns of fornix – prominence from FoM prominence from FoM blends in the lateral blends in the lateral wall wall
Ventricles of the BrainVentricles of the Brain
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.
Ventricles of the BrainVentricles of the Brain
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)
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
Floor – Floor – From Optic chiasm to From Optic chiasm to
ASAS Ant ½ diencephalicAnt ½ diencephalic Post ½ Post ½
mesencephalicmesencephalic
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
ASAS Through midbrainThrough midbrain Into 4Into 4thth ventricle ventricle
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
Midline slit Foramen Midline slit Foramen of Magendieof Magendie
Comunicates with Comunicates with cerebellomedullary cerebellomedullary cisterncistern
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
Demarcates Demarcates medullary and pontine medullary and pontine partsparts
Overly vestibular area Overly vestibular area at lateral angle at lateral angle
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
Ventricles of the BrainVentricles of the Brain
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
CSF PhysiologyCSF Physiology
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
CSF PhysiologyCSF Physiology
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 PhysiologyCSF Physiology
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
CSF PhysiologyCSF Physiology
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
CSF PhysiologyCSF Physiology
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
CSF PhysiologyCSF Physiology
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 physiologyCSF physiology
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
CSF PhysiologyCSF Physiology
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
CSF physiologyCSF physiology
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
CSF physiologyCSF physiology
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
CSF PhysiologyCSF Physiology
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