Ventricles of brain

MENINGES,VENTRICLES,
CEREBROSPINALFLUIDAND
BOOLDSUPPLYOFTHEBRAIN
Mehdi Hayat Khan
BSN,M.Phill Physiolog,MSN*
Nursing Lecturer
mehdisnc05@gmail.com

Ventricle of the brain
Copyright 2017@Mehdi Hayat Khan

OverviewofTheMeninges
• TheMeningesarethe membranecoveringthe brain andspinalcord.
• TheMeningesconsistof three membranes:
1. Thedura mater,
2. Thearachnoid mater,
3. Thepia mater.

TheMeninges
1. Dura mater -
strong, "Tough mother"
a. Falx cerebri
b. Falx cerebelli
c. Tentorium cerebelli
d. Diaphragma sella
2. Arachnoid - spidery,
holds blood vessels
3. Pia mater - "delicate
mother"

TheFalxCerebri
• It is asickle-shaped fold ofdura mater that lies in the midline between
the two cerebral hemispheres.
• Its narrow end in front is attached to the internal frontal crest and the crista
galli.
• Its broad posterior part blends in the midline with the upper surface of the
tentorium cerebelli.
• Thesuperior sagittal sinus runs in its upper fixed margin, the inferior sagittal
sinus runs in its lower concave free margin, and the straight sinus runs along
its attachment to the tentorium cerebelli.

TheTentorium Cerebelli
• Thetentorium cerebelli isacrescent-shaped fold of dura mater that roofs over
theposterior cranialfossa.
• It coversthe upper surfaceof the cerebellum and supports theoccipital
lobesof the cerebral hemispheres.

TheFalxCerebelli
• Thefalx cerebelli is a small, sickle-shapedfold of dura mater that is attached to
the internal occipital crest and projects forward between the twocerebellar
hemispheres.
• Its posterior fixed margin contains the occipitalsinus.

TheDiaphragma Sellae
• Thediaphragmasellae isasmallcircular foldof dura mater that forms the roof
for the sella turcica.
• Asmall opening in its center allowspassage of the stalk of the pituitary gland

Dural Nerve Supply
• Branchesof the trigeminal, vagus,andfirst three cervicalnervesandbranchesfrom
the sympathetic systempassto thedura.
• Theduraissensitiveto stretching,which producesthe sensationofheadache.

Dural Blood Supply
– DuralArterialSupply
• Thedura mater’s arteries supply from
the internal carotid, maxillary,
ascending pharyngeal, occipital, and
vertebral arteries.
• Fromaclinical standpoint, the
most important isthemiddle
meningeal artery, which is
commonly damagedin head
injuries.
– DuralVenousDrainage
• Themeningeal veinslie in the
endosteal layer ofdura.
• Themiddle meningeal vein follows
the branchesofthe middle
meningealartery and drains into the
venousplexusor the sphenoparietal
sinus.
• Theveinslie lateral tothe arteries.

VENTRICLES(Ventricular System)
• Aventricle isaninternal cavity of
the brain.Within the brain,
which isfilled with cerebrospinal
fluid(CSF).
• Theventricular systemis
composedof two lateral
ventriclesand two midline
ventricles( third andfourth
ventricles).

Continue
– Thechambersare connected to allow the flow of cerebrospinal fluid via two
interventricular foramen(referred to asthe foramenofMonro) and the
cerebralaqueduct(referred to asthe aqueductof Sylvius).

VENTRICLES(Ventricular System)
1) Lateralventricle
2) Thirdventricle
3) Fourthventricle
4) Centralcanalof the medulla
oblongata & spinalcord

Centralcanalof
medulla
oblongata&
spinalcord
Lateralview to showthe ventricular systemof the CNS
Fourthventricle
Lateralventricle
Thirdventricle
Interventricular
foramen(Monro)
Cerebral
aqueduct

Lateral Ventricles
• Thelateral ventricles aretwo curvedshaped cavities located within the
cerebrum.
• Thelateral ventricles areseparatedbythe septumpellucidumand do not
communicate directly.

Lateral Ventricles
– These cavities lie within the cerebral hemispheres, one on each side of the
median plane just below the corpus callosum.
– They are separated from each other by a thin membrane, the septum lucidum,
and are lined with ciliated epithelium.
– They communicate with the third ventricle by interventricular foramina

o C-shapedcavity& maybedivided into :
2.Anterior
horn
1.Body
3. Posterior
horn
Third
ventricle
4.Inferior
horn
Fourth
ventricle
Lateralview of the ventricular cavitiesof thebrain
Lateralventricle

Third ventricle
o Thethird ventricle is anarrow
cavity or aslit like cleft between the
two parts of thalamus
o Communicates ;
• Anteriorly with lateral ventricles
through interventricularforamina
(of monro)
• Posteriorly with fourth
ventricle through cerebral
aqueduct(of sylvius)

Fourthventricle
• Thefourth ventricle Isa rhomboid or diamond shapedcavity.
• It isawide and flattened space located just anterior to the cerebellum
and posterior to the upper, or superior, half of the medulla oblongata
andthepons.
• It is continuous below with the central canal of the spinal cord
and communicates with the subarachnoid space by foramina in
its roof.
• Cerebrospinal fluid enters the subarachnoid space through these
openings and through the open distal end of the central canal of
the spinal cord.

Cerebellum
Pons
Medulla
oblongata
(superior
half)
Sagittalsectionof the 4th ventricle
Cerebral
aqueduct
Central
canal
(spinal
cord)
Fourthventricle
Fourth
ventricle
ANTERIOR
POSTERIOR

CHOROIDPLEXUS
– It is formed by invaginating of vascularpia mater intothe ventricular cavity
• It becomeshighlyconvoluted & produce aspongy-like appearance
• It enters the3rd and 4th ventricles through their roofs, and the lateral
ventricles through the choroid fissure produces cerebrospinalfluid (CSF)

Sitesof formation
1. Choroidplexusof the ventricle cavities, mostly is formed in the LATERAL
VENTRICLES
2. Someoriginate from the ependymalcells liningthe ventricles
3. Somefrom the brain substancesthroughperivascular spaces

Movement of CSFinside the
ventricle is controlled by the:
1. Pulsation of the artery in the choroid plexus
2. Bythe aid of the cilia & microvilli of the ependymal cells

Cerebrospinalfluid Circulation
• TheCSFis formed in the lateral ventricles escapesby the foramen of monro
into the third ventricle
• From the third ventricle bythe aqueduct into the fourthventricle.
• Then from the fourth ventricle the fluid is poured into thesubarachnoid
spacesthrough the medial foramen of majendie and the two lateral
foramina of luschka.
• There is no evidence that functional communications between the cerebral
ventricles and the subarachnoid spacesexist in any region except from the
fourth ventricle.

Functionof the CSF
1. Cushions& protectsthe CNS fromtrauma
2. Providesmechanicalbuoyancy&support for the brain
3. Serves asareservoir& assistsin the regulation ofthe contents of theskull
4. NourishestheCNS
5. Removesmetabolites from theCNS
6. Servesasapathwayfor pineal secretionsto reach the pituitary gland

Siteof formation
Choroidplexusof the
lateral ventricle
1. Lateralventricle
2. Thirdventricle
Interventricular foramina
3. Fourthventricle
Cerebral aqueduct
3.2Lateral
foramina
(Luschka)
3.2Lateral
foramina
(Luschka)
3.1 Median
foramen
(Magendie)
4. Subarachnoidspace
Inferiorly
Superiorly
Absorbed
Superiorly
Absorbed

Factors that facilitate the flow of
CSFin subarachnoid space
1. Pulsation of the cerebral &spinal arteries
2. Movements of the vertebralcolumn
3. Respiration & coughing
4. Changingof thepositions

Absorption of CSFinto dural
venoussinuses
• Main sites- arachnoid villi (project into dural venous sinuses,
especially,superior sagittalsinus).
• Arachnoid villi arecoveredby endothelium of the venous sinus
• Arachnoid villi tend to be grouped together & form elevationsknown
as arachnoid granulations
• CSFpressure>>the pressure in thesinus
• Therate of absorption ofCSFthrough the arachnoid villi controls the
CSF pressure.

Hydrocephalus
• Theterm hydrocephalusis derived from the Greek words "hydro" meaning
water and "cephalus" meaninghead.
• It is excessive accumulation of fluid in the brain

References
– Medical Physiology Guyton and hall
– Anatomy and physiology by Ross and Wilson 12e

Ventricles of brain

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