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Dr. Nimir
Dr. Safaa
Objectives
 Describe the ventricles of brain and importance of their
choroids plexus.
 Summarize the pathway of cerebrospinal fluid (CSF)
circulation.
 Locate the safe sites for the lumbar puncture.
 Identify brain ventricles in CT scan, MRI and
ventriculograms.
 Ventricles:
 They are four fluid-filled
cavities located within
the brain, there are two
lateral ventricles, third
ventricle, and fourth
ventricle.
 Lateral ventricles(one in
each hemisphere)
communicate through
interventricular foramina
(of Monro) with third
ventricle.
 The third is connected to
the fourth by cerebral
aqueduct (of Sylvius).
 Lateral Ventricles:
 The ventricle is C-shaped
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cavity divided into a body,
whithin parietal lobe,
anterior horn in frontal
lobe, posterior in
occipital lobe, and
inferior in temporal lobe.
The body has:
Roof & lateral wall
formed by corpus
callosum.
Floor by body of caudate
nucleus & thalamus.
Medial wall by septum
pellucidum.
 Anterior horn has:
 Roof & lateral wall formed
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by anterior part of corpus
callosum.
Floor by head of caudate
nucleus.
Medial wall by septum
pellucidum.
Posterior horn has:
Roof & lateral wall formed
by fibers of tapetum of
corpus callosum.
Medial wall formed
superiorly by forceps major
of corpus callosum &
inferiorly by calcar avis of
calcrine sulcus.
 Inferior horn has:
 Roof formed by fibers of tapetum of corpus callosum &
tail of caudate nucleus .
 Floor formed laterally by collateral eminence, produced
by collateral fissure, and medially by hippocampus.
 Choroid plexus of the
lateral ventricle:
 It is a vascular plexus
composed of pia mater
covered with ependymal
lining of the ventricular
cavity.
 It enters the ventricle
through choroid fissure
between fornix &
thalamus.
 Its function is to produce
cerebrospinal fluid.
 Third Ventricle:
 Is space between two
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thalami.
Its anterior wall is formed
by lamina terminalis.
Its posterior wall is
formed by epithalmus.
Its roof formed by tela
choroidea which is below
fornix and corpus
callosum.
Its floor is formed by:
Optic chiasma
Tuber cinereum,
Infundibulum
Mammillary bodies.
 Its choroid plexuses is
formed from tela
choroidea.
 The tela choroidea is a
two-layered fold of pia
mater that projects
through the roof of the
ventricle and is covered
by ependyma.
 It communicates with
lateral ventricles through
interventricular
foramina (of Monro), and
it communicates fourth
ventricle through
cerebral aqueduct.
 Fourth ventricle:
 It is anterior to
cerebellum and posterior
to pons and superior half
of medulla oblongata.
 Its floor (Rhomboid
Fossa) formed by
posterior surface of pons
& upper medulla.
 Its roof formed by
superior medullary velum
& inferior medullary
velum.
 Inferior medullary
velum contains median
aperture of Magendie &
lateral apertures of
Luschka through which
CSF pass to
subarachnoid space.
 Its choroid plexus has a
T shape which formed
from highly vascular
tela choroidea.
 Cerebrospinal fluid (CSF)
is formed in ventricles by
choroid plexuses.
 Pass from lateral
ventricles to third
through interventricular
foramina then through
cerebral aqueduct to
fourth ventricle.
 From fourth to
subarachnoid space
through foramina of
Luschka & Magendie
Absorption(Drainage)
 The main sites for the
absorption of the
cerebrospinal fluid are
the arachnoid villi that
project into the dural
venous sinuses
 Especially the superior
sagittal sinus.
 The arachnoid villi tend
to be grouped together
to form elevations
known as arachnoid
granulations.
 Lumbar puncture:
 With a careful
aseptic technique
and under local
anesthesia,
Lumbar puncture
(spinal tap)
needle, fitted
with a stylet, is
passed into the
vertebral canal
above or below
the fourth lumbar
spine.
 A) Pre-operative axial
head CT scan
demonstrating
enlarged ventricles.
 B) Post-operative
axial head CT
demonstrating
decrease in the size of
the lateral and third
ventricles after shunt
placement.