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Brain

1. VENTRICLES OF
THE BRAIN
BY : HARSHITA HADA, 232E

2. TABLE OF CONTENTS
FOURTH
VENTRICLE04
LATERAL
VENTRICLES
INTRODUCTION
01
02
What are the ventricles of
the brain.
THIRD
VENTRICLE03

3. The ventricles of the brain are a communicating network
of cavities filled with cerebrospinal fluid (CSF) and
located within the brain parenchyma.
●The ventricular system is composed of
● 2 lateral ventricles (PAIRED)
● the third ventricle,
● and the fourth ventricle.
The choroid plexuses are located in the ventricles
produce CSF, which fills the ventricles and subarachnoid
space, following a cycle of constant production and
reabsorption.

●
●

What are
ventricles

4. VENTRICLES
The lateral ventricles communicate with the third ventricle
through interventricular foramen( foramen of monro ), and
the third ventricle communicates with the fourth ventricle
through the cerebral aqueduct.
Cerebrospinal fluid (CSF) is secreted by the epithelial cells
of choroid plexuses, filling the ventricular system.

5. LATERAL
VENTRICLE
The largest cavities of the ventricular
system are the lateral ventricles. They are
two irregular cavities situated one in each
cerebral hemisphere.
Each lateral ventricle communicates with
the third ventricle through an
interventricular foramen (foramen of
Monro). Each lateral ventricle consists of:
1. A central part or Body.
2 .Three horns: Anterior, posterior and
inferior
01

6. BODY OR CENTRAL PART
The central part of the lateral ventricle is elongated
anteroposteriorly. Anteriorly, it becomes continuous with the
anterior horn at the level of the interventricular foramen.
Posteriorly, the body reaches the splenium of the corpus
callosum.

It is triangular in cross section and has a roof, floor, and a medial
wall; the roof and floor meeting on the lateral aspects.

1. The ROOF is formed by the trunk of the corpus callosum
2.The MEDIAL WALL is formed by the septum pellucidum and by
the body of the fornix, which is common to two lateral ventricles.
3.The FLOOR is formed mainly by the superior surface of the
thalamus, medially, and by the caudate nucleus laterally.
Between these two structures are the stria terminalis and the
thalamostriate veins.

7. INFERIOR HORN

This is the largest horn of the lateral ventricle. It begins at the junction of the
central part with the posterior horn of the lateral ventricle; and extends into
the temporal lobe .
Boundaries

Roof and lateral wall
1 Chiefly the tapetum
2 Tail of caudate nucleus
3 Stria terminalis
4 Amygdaloid body

Floor
1 Collateral eminence raised by the collateral sulcus
2 Hippocampus, medially.
In the inferior horn, the line of ependymal invagination by the choroid plexus
(i.e. the choroid fissure) lies between the stria terminalis and the fimbria.

8. This is the part of the lateral ventricle which lies in front of the
interventricular foramen and extends into the frontal lobe. It is
directed forwards, laterally and down-wards, and is triangular on
cross-section.

Boundaries
Anterior
Posterior surface of genu and rostrum of the corpus callosum.
Roof
Anterior part of the trunk of the corpus callosum.
Floor
1 Head of the caudate nucleus.
2 Upper surface of the rostrum of the corpus callosum.
Medial
1 Septum pellucidum
2 Column of fornix

ANTERIOR HORN

9. This is the part of the lateral ventricle which lies behind the
splenium of the corpus callosum and extends into the occipital
lobe. It is directed backwards and medially (Fig. 9.8).
Boundaries
Floor and medial wall
Bulb of the posterior horn raised by the forceps major.
2 Calcar avis raised by the anterior part of the calcarine sulcus.
Roof and lateral wall
Tapetum fibres of optic radiation.
POSTERIOR HORN

10. The third ventricle is a narrow funnel-shaped cavity of the
brain. It is located in the midline between the two hemispheres
of the diencephalon of the forebrain . As such, the third
ventricle directly communicates with other ventricles:

It communicates with each lateral ventricle via the foramen of
Monro,
It communicates with the fourth ventricle via the cerebral
aqueduct (of Sylvius).
The third ventricle can be described as a cuboid structure that
has a roof, floor and four walls (anterior, posterior, and two
lateral). Similar to the other brain ventricles, the main function
of the third ventricle is to produce, secrete and convey
cerebrospinal fluid.
THIRD VENTRICLE
02

11. RECESSES
Recesses are extensions of the cavity. These are :
The cavity of the third ventricle extends into four recesses:
The supra-optic recess is located superior to the optic chiasm and inferior to
the lamina terminalis.
The infundibular recess is found on the floor of the third ventricle, between
the optic chiasm and the mamillary bodies. It extends inferiorly, into the
pituitary stalk.
The pineal recess extends posteriorly. More specifically, it projects into the
pineal body, between the cranial and caudal lamina of the pineal gland.
The suprapineal recess is located between the superior portion of the pineal
gland and the inferior aspect of the tela choroidea in the roof of the ventricle.
It extends posteriorly, behind the posterior wall of the third ventricle


THIRD VENTRICLE

12. THIRD VENTRICLE
ANTERIOR WALL:
Lamina terminalis
Anterior commissure
Anterior columns of fornix. The two column of ene fornix diverge, pass downwards and
backwards, and the mammillary body.
sink into the lateral wall of the third ventricle terrarit
Posterior Wall
Pineal body
Posterior commissure (in the lower lamina of the pineal stalk)
Cerebral aqueduct

Posterior Wall
Pineal body
Posterior commissure (in the lower lamina of the pineal stalk)
Cerebral aqueduct

13. THIRD VENTRICLE

Roof
It is formed by body of fornix and the ependyma lining the under surface of the tela
choroidea of the third ventricle. The choroid plexus of the third ventricle projects
downwards from the roof.
At the junction of the roof with the anterior and lateral walls, there are the interventricular
foramina.
Floor
It is formed by hypothalamic structures:
1 Optic chiasma
2Tubercinerium
3 Infundibulum (pituitary stalk)
4 Mammillary bodies
5 Posterior perforated substance
6 Tegmentum of the midbrain.
At the junction of the floor with the anterior wall, there is the optic recess

14. THIRD VENTRICLE
Lateral Wall
It is formed by the following.
1 Medial surface of thalamus (in its posterosuperior part)
2 Hypothalamus (in its anteroinferior part)
The hypothalamic sulcus which separates the thalamus from the hypothalamus.
The sulcus extends from the interventricular foramen to the cerebral aqueduct.
Note that
a. The interthalamic adhesion connects the medial surfaces of the two thalami
and crosses the ventricular cavity.
b. The habenular stria lies at the junction of the roof and the lateral wall. The two
striae join posteriorly at the habenular commissure.
c. The columns of the fornix, as already indicated, run downwards and backwards
to reach the mammillary bodies. The columns lie beneath the lateral wall of the
ventricle.

15. FOURTH VENTRICLE
The fourth ventricle is one of the interconnected fluid-filled cavities
within the human brain. There are four of these cavities in the brain,
three of which are located within the cerebrum (two lateral ventricles
and the third ventricle). These cavities and their content constitute the
ventricular system of the brain.

The fourth ventricle lies dorsal to the pons and medulla (of the
brainstem) and ventral to the cerebellum. It extends from the cerebral
aqueduct (aqueduct of Sylvius) superiorly, extending inferiorly into the
central canal of brainstem and spinal cord. Its surface is lined by an
epithelial layer called the ependyma, and is bathed with cerebrospinal
fluid (CSF).
03

16. The lateral walls of the fourth ventricle are formed by the
cerebellar peduncles. The superior part of these walls is
formed by the superior cerebellar peduncle. The inferior part is
formed by the inferior cerebellar peduncle and by the gracile
and cuneate tubercles of the brainstem.

It has two major extensions, known as the lateral recesses,
one on either side of the midline. These recesses extend
laterally between the inferior cerebellar peduncle and the
peduncle of the flocculus of the cerebellum, to open into the
subarachnoid space as the lateral apertures (foramina of
Luschka).
LATERAL WALLS

17. The roof of the fourth ventricle has presents a 'tent-like' apex at the intersection of it's
superior and inferior parts. This apex, also known as the fastigium, extends into the white
core of the cerebellum.

The superior part of the roof is formed by the superior cerebellar peduncles and the
superior medullary velum (thin sheet of white matter). The inferior part of the roof is
made of non-nervous tissue, the inferior medullary velum. However, like other parts of
the ventricle, it is lined by a membrane consisting of ependyma and a double fold of pia
mater which constitutes the tela choroidea of the fourth ventricle. Laterally on each side
of the midline, this membrane extends and joins the inferior cerebellar peduncles. The
lower part of the membrane has a large aperture, the foramen of Magendie. This is the
median aperture of the fourth ventricle, through which the entire ventricular system
communicates.
ROOF

18. The cavity or fossa of the fourth ventricle communicates with the third
ventricle superiorly as a continuation of the cerebral aqueduct. The inferior
portion of the cavity is known as the obex (Latin for barrier), and extends
into the central canal of the brainstem, which in turn runs through the
vertebral column. The cavity also communicates with the subarachnoid
space through the three apertures mentioned above.
CAVITY

19. A PICTURE
ALWAYS
REINFORCES
THE CONCEPT

20. The floor of the fourth ventricle is also referred to as the rhomboid fossa
because of its shape. It is divisible into a right and left half by the posterior
median sulcus, and into a superior and inferior triangle by the striae
medullares.

1.The upper triangular part is formed by the posterior surface of the
pons.
2 . The lower triangular part is made up of the upper part of the posterior
surface of the medulla and an intermediate part at the junction of the
medulla and pons.
3. The intermediate part is prolonged laterally over the inferior cerebellar
peduncle as the floor of the lateral recess. Its surface is marked by the
presence of delicate bundles of transversely running fibres that constitute
the striae medullares.
4. The lowest part of the floor of the fourth ventricle is referred to as the
calamus scriptorius. Each inferolateral margin of the floor is marked by a
narrow white ridge called taenia. The right and left taeniae meet at the
inferior apex of the floor to form a small fold called the obex.
FLOOR

21. Tela choroidea and choroid plexuses
The tela choroidea and choroid plexus of the fourth ventricle
are other notable features of the fourth ventricle. The tela
choroidea is made up of two layers of pia mater. The choroid
plexus is a highly vascular structure, and is similar in structure
to those of the lateral and third ventricles. It lies within the folds
of pia mater forming the tela choroidea.

These structures are responsible for the production of the
cerebrospinal fluid (CSF), which has several functions:

Fills the subarachnoid space and ventricles
Plays a protective role to the brain;
Supplies nutrients to the brain;
Removes waste products from the brain, which are absorbed by
the arachnoid villi.

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THANKS FOR YOUR
ATTENTION
BY ; HARSHITA HADA, 232E
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