NEUROANATOMY

Lecture : 6

The Ventricles and Meninges of the Brain ,The Cerebro-Spinal Fluid

Prepared and presented by:Dr. Iyad Mousa Hussein ,

MD, Ph.D in NeurologyHead of Neurology Department

Nasser Hospital

1. The Ventricles of the Brain.

2. Definition, Site, Communicates, and Parts of the Lateral Ventricle.

3. Definition, Site, Communicates, and Parts of the Third Ventricle.

4. Definition, Site, Communicates. and Parts of the Fourth Ventricle.

5. The Meninges and Intracranial Spaces of the Brain.

6. Dural Nerve Supply.

7. Headaches due to Diseases of the Teeth, Paranasal Sinuses, and

Eyes.

9. Definition, Production, Circulation, Absorption, and Functions of the

Cerebro-Spinal Fluid.

10. Characters of the normal Cerebro-Spinal Fluid.

LECTURE OBJECTIVES:

► The brain and spinal cord float within a protective bath of

cerebrospinal fluid (CSF), which is produced by the

choroid plexus within the ventricles of the brain.

► Each part of the CNS contains a component of the

ventricular system.

► The ventricles contains about 35 ml of CSF.

The Ventricles of the Brain

There are four interconnected ventricles in the brain:

1. Two lateral ventricles (Right and Left).

2. Third ventricle.

3. Fourth ventricle.

The Ventricles of the Brain

The Ventricles of the Brain

Definition: it is the cavity of the cerebral hemispheres.

There are two lateral ventricles (Right & Left), one in

each cerebral hemisphere.

Site: it is the cavity present in each cerebral hemisphere.

Communications:

It communicates with the third ventricle through the

interventricular foramen of Monro.

The Lateral Ventricle

1. The body (central part): lies in the parietal lobe. It

communicates with the three horns.

2. Anterior horn (frontal): lies in the frontal lobe.

3. Posterior horn (occipital): lies in the occipital lobe.

4. Inferior horn (temporal): lies in the temporal lobe.

Parts of the lateral ventricle

The Third VentricleThe Third Ventricle

Definition: It is a narrow cavity situated in the midline

between two thalami.

it is the a cavity of the diencephalon.

Site: it is lying in the median plane between the right

and left thalami.

1. Anterosuperiorly: on each side, it communicates

with each lateral ventricle by an interventricular

foramen of Monro.

2. Posteroinferiorly: in the median plane, it

communicates with the fourth ventricle through the

cerebral aqueduct (of Sylvius), which passes

through the midbrain.

Communications of the Third Ventricle

1. Optic recess: just in front of the optic chiasma.

2. Infundibular recess: in the infundibulum.

3. Supra-pineal recess: just above the pineal body.

4. Pineal recess: in the pineal body.

Recesses of the third ventricle

Choroid Plexus of the Lateral and Choroid Plexus of the Lateral and Third Third !!!!!!! !!!!!!! VentriclesVentricles

Definition: It is the cavity of the hindbrain (Rhombencephalon)Rhombencephalon).

Position: it lies between:

1. The dorsal surfaces of the pons and upper part of the

medulla anteriorly.

2. The ventral surface of the cerebellum posteriorly.

The Fourth Ventricle

1. Superior angle: where the fourth ventricle is continues

with the aqueduct of the midbrain.

2. Inferior angle: where the fourth ventricle is continuous

with central canal of the closed medulla.

3. Right & Left lateral angle: each lateral recess opens into

the subarachnoid space (by right and left foramen

Luschka).

Angles of the fourth ventricle

1. cerebral aqueduct (of Sylvius): in the superior

median plane (superior angle), it communicates with

third ventricle.

2. Central spinal canal: in the inferior median plane

(inferior angle).

3. One median foramen (foramen of Magendie): in

the lower part of the inferior medullary velum.

4. Two lateral foramens (foramens of Lushka): one in

each lateral recess.

Through foramens of Magendie and Lushka, the CSF

leaves the fourth ventricle to the subarachnoid space.

Communications of the Fourth Ventricle

It is protective coverings (membranes) over the surface of

the brain and spinal cord.

The brain is surrounded by 3 membranes, from inside

outwards they are:

1. Pia mater.

2. Arachnoid mater.

3. Dura mater.

The Meninges of the Brain

► It is a vascular membrane forming the inner most

covering membrane of the brain.

► The choroid plexus of the lateral and third ventricles

are formed by invagination of th pia mater.

► It send sheaths around the cranial nerves in the

cranial cavity.

I. The Pia Mater

► It is a thin membrane lying outside the pia mater.

► It send sheaths around the cranial nerves till their

points of exit from the skull.

► It is consist of arachnoid villi (microscopic) and

arachnoid granulations (macroscopic).

► It is separated from the pia mater by a narrow space

called subarachnoid space containing CSF.

II. The Arachnoid Mater

► It is a thick membrane forming the outermost

covering of the brain.

► It consist of two layer:

1. Outer or endosteal layer: lines the inner surface

of the skull bones.

2. Inner or meningeal layer.

► Surrounds and protects the brain.

► The two layers of the dura are fused together except

in certain places where they separate to form

venous sinuses.

III. The Dura Mater

1. Epidural space: it is located between the two layers of

the dura mater.

2. Subdural space: it is located between the dura mater and

arachnoid mater. It contains a small amount of serous

fluid.

3. Subarachnoid space: it is located between the arachnoid

and pia mater. It contains CSF and blood vessels.

The Intracranial Spaces

1. Trigeminal nerve:

a. Ophthalmic nerve: supplies the dura mater of

anterior cranial fossa.

b. Maxillary and Mandibular nerves: supply the

dura matter of middle cranial fossa.

2. Vagus and Glossopharyngeal nerves: supply the

dura matter of middle cranial fossa.

3. The first three cervical spinal nerves.

4. Sympathetic trunk.

Dural Nerves Supply

Dental infection and sinusitis are common causes of

headache. The pain is referred to the skin of the face

and head along the branches of the trigeminal nerve.

Headaches due to Diseases of the Teeth, Paranasal Sinuses, and Eyes

Definition: it is the fluid which circulates in the

ventricles and central canals of the CNS and also

fills the subarachnoid space.

Production of the CSF:

It is secreted by the choroid plexuses of lateral,

third and fourth ventricles.

The Cerebro-Spinal Fluid

The CSF in each lateral ventricle → interventricular

foramen of Monro → third ventricle → aqueduct of

midbrain → fourth ventricle → some fluid enter the

central canal of spinal cord but the majority passes

through the 3 foramina (one median of foramen

Magendie & two lateral foramins of Lushka) →

subarachnoid space were it flows over the surface of

the brain and spinal cord.

Circulation of the Cerebro-Spinal Fluid

Absorption of the Cerebro-Spinal Fluid

The CSF is absorbed by means of arachnoid villi and

arachnoid granulations which absorbs the CSF from

the subarachnoid space into the dural venous sinuses

to reach the blood stream.

1. Cushions and protects the central nervous system

from trauma.

2. It takes the place of the lymph in the CNS which is

devoid of lymphatic vessels.

3. Regulation of the intracranial pressure.

4. Removes metabolites and toxics from the central

nervous system.

5. Nourishes the central nervous system.

Functions of the Cerebro-Spinal Fluid

Appearance: clear watery fluid, isotonic.

Amount: 100- 150 cc.

Replacement: it continuously produced and

absorbed at a rate of 400-500 cc daily (it is replaced

3 times per day).

Pressure: 100-180 mm. of water.

Rate of production: 0,3-0,4 ml/min.

Cells: 0-5 WBCs per cubic millimeter.

Glucose: 60 mg/dl (70% of serum glucose).

Total protein: 15-50 mg/dl.

Characters of the Normal Cerebro-Spinal Fluid