Ventricles Of Brain
By
Manoj Kollukkad
• The interior of brain
contain a series of
cavities that are filled
with cerebrospinal fluid
& are called as the
ventricles.
• The diencephalon
contains a median cavity
filled with cerebrospinal
fluid & is called as the
third ventricle.
• Each cerebral hemisphere
contains another cavity
called the lateral
ventricles.
• Each lateral ventricle
opens in to third ventricle
through a foramen called
the interventricular
foramen.
• The third ventricle is
continuous with the cerebral
aqueduct, which is the cavity
present in the mid brain.
• The fourth ventricle is situated
dorsal to the pons & medulla
and ventral to the cerebellum
• It communicates inferiorly with
the central canal which traverses
the lower part of the medulla &
spinal cord.
• The entire ventricular system is
lined by an epithelial layer
called the ependyma.
The Third Ventricle
• Median cleft between the two
thalamus.
• Developmentally it represents the
cavity of the diencephalon, except the
area in front of the interventricular
foramen which is derived from the
median part of the telencephalon.
• The cavity is lined by ependyma.
• Antrosuperiorly on each side it
communicates with the lateral
ventricles, through interventricular
foramen.
• Bounded anteriorly by the column of
fornix & posteriorly by the tubercle of the
thalamus.
• Posteroinferiorly in the median plane
it communicates with the 4th ventricle
through cerebral aqueduct.
Recesses are extensions of
the third ventricle.
•They are
1. The infundibular recesses
2. The optic recesses
3. Anterior recess (vulva of
the ventricle)
4. The suprapinial recesses
5. The pinial recesses
Boundaries of the third ventricle
• Anterior wall is formed by:-
• Lamina terminalis
• Anterior commissure
• Collumn of fornix
• The 2 columns are of the fornix diverge
& pass downwards & backwards & sink
in to the lateral wall of the 3rd ventricle
to reach the mamillary body.
• Posterior wall is formed by:-
• The pinial body
• The posterior commissure
• The cerebral aqueduct
• Roof is formed by
• The ependyma lining the under surface
of the tela choroidia of the 3rd
ventricle.
• The choroid plexus of 3rd ventricle
project downwards from the roof.
• At the junction of the roof with
anterior & lateral walls there are the
interventricular foramina.
• Floor is formed by:-
• The hypothalamic structures such as
• The optic chiasma
• The tuber cinerium
• The infundibulum
• The mamillary bodies
• The posterior perforator substance
• Tegmentum of mid brain
• At the junction of the floor with the
anterior wall there is optic recess.
• The Lateral wall is formed by
• The medial surface of the thalamus
• The hypothalamic sulcus
• The interthalamic adhesion
• The hypothalamus
• The column of the fornix
Applied anatomy
• The 3rd ventricle is a narrow space which is obstructed by local
brain tumours or by developmental defects.
• The obstruction leads to intracranial pressure in adults &
hydrocephalus in infants
• Tumors in the lowest part of the 3rd ventricle give rise to
hypothalamic symptoms, like Diabetes insipidus , obesity etc
• The site of obstruction can be found out by ventriculography.
• In antero post view 3rd ventricle is seen normally as a narrow
vertical midline shadow.
• Dilatation of 3rd ventricle would indicate obstruction at a lower
level eg, cerebral aqueduct.
• If the obstruction is in the 3rd ventricle, both lateral ventricles
are dilated symmetrically.
• Obstruction at an interventricular foramen causes unilateral
dilatation of the lateral ventricle of that side.
The Lateral Ventricle
• Are two irregular cavities situated
one on each cerebral hemispheres.
• Communicate with the 3rd ventricle
through an interventricular
foramen.
• Consists of
• A central part
• Three horns
• The anterior horn
• The posterior horn
• The inferior horn
Lateral view of ventricles
Superior view of ventricles
Central Part Of Lateral
Ventricle
• Roof is formed by
• The under surface of the
corpus callosum
• Floor is formed (from
lateral to medial) by
• The body of caudate nucleus
• The stria terminalis
• The thalamostriate vein
• The lateral portion of the
upper surface of the
thalamus
• Medial wall is formed by
• The septum pellucidum
• The body of fornix
Coronal sections of the brain passing through the anterior body or central part
of the lateral ventricle
Anterior Horn Of The Lateral
Ventricle
• Part of the lateral ventricle
which lies in front of the
interventricular foramen&
extends in to fontal lobe.
• Directed forwards, laterally &
downwards.
• Triangular on cross section
Boundaries
• Anteriorly
• The posterior surface of the genu & rostrum of the corpus callosum.
• Roof
• The anterior part of the trunk of the corpus callosum.
• Floor
• The head of the caudate nucleus
• The upper surface of the corpus callosum
• Medially
• The septum pellucidum
• The column of fornix
Posterior Horn Of Lateral
Ventricle
• The part of the lateral ventricle
which lies behind the splenium
of the corpus callosum &
extends in to the occipital lobe.
• Variable in size & may be
absent.
• Directed backwards & medially
Boundaries
• Medial wall
• The bulb of the posterior horn raised by the forceps major
• The calcar avis raised by the anterior part of the calcarine sulcus
• The roof, lateral wall, and floor are formed by the tapetum
of the corpus callosum
Inferior Horn Of The
Lateral Ventricle
• The largest horn of the lateral
ventricle
• It begins at the junction of the
central part with the
posterior horn of the lateral
ventricle & extends in to the
temporal lobe.
Boundaries
• Roof ( And Lateral Wall )
• Chiefly tapetum
• The tail of caudate nucleus
• The stria terminalis
• The amygdaloid body
• Floor
• The collateral eminance raised by the collateral sulcus
• Medially
• The hippocampus
The Fourth Ventricle
• The cavity of the hind brain is called the Fourth Ventricle
• It is tent shaped space situated between the pons & medulla infront & cerebellum behind.
Communications
• Superiorly it communicates with the III ventricle through the cerebral aqueduct.
• Inferiorly it is continuous with the central canal of the medulla & spinal cord.
• Dorsally in the lower part of the roof, there is a median aperture through which it communicates
with the subarachnoid space (cisterna magna )
• On either side, again it communicates with the subarachnoid space through the lateral aperture
Recesses of IV ventricle
• A median dorsal recess extends in to the
white core of the cerebellum above the
nodule
• Two lateral dorsal recesses one on each
side extend laterally between the inf
cerebellar peduncle ( in front ) and the stem
of flocculus (behind ) they reach up to the
flocculus it self.
• Each recess opens at its lateral end through
the foramen of Luschka
Boundaries
Lateral boundaries
• On each side the IV ventricle is bounded by
• Inferolaterally by
• The gracile tubercle
• The fasiculus cuneatus
• The cuneate tubercle
• Inferior cerebellar peduncle
• Superolaterally by
• The superior cerebellar peduncle
Roof of the fourth ventricle
• The roof is tent shaped & is
projecting in to the cerebellum.
• It is formed by
• The superior cerebellar peduncle
• The Superior medullary velum
• Thin sheet of white matter, the
superior medullary velum that
stretches between the two superior
cerebellar peduncles
• The Inferior medullary velum
• Thin sheet of non-nervous tissue that
is formed conjointly by the
ventricular ependyma and the pia
mater.
Tela choroidia & choroid plexus of the
IV ventricle
• The choroid plexus is a tuft of
capillaries that project into the
cavity of the 4th ventricle through
the lower part of its roof.
• The choroid plexus of the IV
ventricle is supplied by a branch
from the posterior inferior cerebellar
artery.
• Lies within the tela choroidia of the IV
ventricle
• The entire plexus is “ T “ shaped, the
vertical limb of the “T” being
double.
• The foramen of Magendie lies
between the two limbs.
• The horizontal limb extends in to
the lateral recess and protrudes
through the foramen of Luschka in
to the subarachnoid space
Floor Of Fourth Ventricle
• It is called the rhomboid fossa
• Formed by
• The posterior surface of the pons)
• The posterior surface of the open part
of the medulla.
• Lined by the ependyma
Deep to the floor there is a layer of
grey matter containing various
cranial nerve nuclei
The following features are seen in the
floor
• A median sulcus divides the floor in
to right & left halves
• On either side of the midline, there
is an elevation called the median
eminence.
• The eminence is bounded laterally
by a sulcus called the sulcus Posterior surface of the brainstem showing
limitans the floor of the fourth ventricle
The following are seen in relation to the
sulcus limitans
• A bluish colored area called the locus
coerulus, deep to which there is
substancia ferruginea.
• A depression called the superior fovea
which lies just lateral to the facial
colliculus.
• Another depression the inferior fovea
that lies above the vagal triangle
The following features are seen in
relation to the median eminens
• The facial colliculus is an elevation
over the upper part of the eminens.
• It lies opposite to the superior fovea.
• It is produced by the underlying
abduscent nucleus & fibres of the facial
nerve as they wind round the nucleus.
• The lower part of the eminens is occupied
by the hypoglossal triangle.
• The hypoglossal nucleus lies deep to this
triangle
• The vestibular area is the area that lies
lateral to the fovea.
• Part of it extends in to the lateral recess
& forms an elevation called the auditory
tubercle
• The tubercle overlies the dorsal cochlear
nucleus & the cochlear nerve
• The stria medullaris are transverse lines
running across the floor.
• They represent the fibres passing from the
arcuate nucleus to the opposite side of the
cerebellum
• The vagal triangle lies below the inferior
fovea between the hypoglossal triangle &
the vestibular area.
• It overlies the dorsal nucleus of the vagus
• The inferolateral margins
of the 4th ventricle are
marked by a narrow
white ridge called tenia.
• The two teniae meet at
the inferior angle of the
ventricle to form a small
fold called obex.
• The obex forms the roof
of the inferior angle of
the 4th ventricle
Applied Anatomy
• Vital centres are situated in the vicinity of the
vagal triangle.
• An injury to this area is there fore fatal
• Infratentorial tumours block the median &
lateral formina situated in the roof of the
ventricle.
• This results in marked & early rise of intra cranial
pressure
