Tag: Ventricular system

Ventricular system

Ventricular system


INTRODUCTION:

  • The ventricular system is a set of four interconnected cavities (ventricles) in the brain, where the cerebrospinal fluid (CSF) is produced.
  • Within each ventricle is a region of choroid plexus, a network of ependymal cells involved in the production of CSF.
  • The ventricular system is continuous with the central canal of the spinal cord (from the fourth ventricle) allowing for the flow of CSF to circulate.
  • All of the ventricular system and the central canal of the spinal cord is lined with ependyma, a specialised form of epithelium.

 DEVELOPMENT:

  • The structures of the ventricular system are embryologically derived from the neural canal, the centre of the neural tube.
  • The prosencephalon divides into the telencephalon, which forms the cortex of the developed brain, and the diencephalon. 
  • The ventricles contained within the telencephalon become the lateral ventricles, and the ventricles within the diencephalon become the third ventricle.
  • The rhombencephalon divides into a metencephalon and myelencephalon. 
  • The ventricles contained within the rhombencephalon become the fourth ventricle, and the ventricles contained within the mesencephalon become the aqueduct of Sylvius.

STRUCTURE:

The system comprises four ventricles:

  1. lateral ventricles right and left (one for each hemisphere)
  2. third ventricle
  3. fourth ventricle
  • There are several foramina, openings acting as channels, that connect the ventricles. 
  • The interventricular foramina (also called the foramina of Monro) connect the lateral ventricles to the third ventricle through which the cerebrospinal fluid can flow.
  • Trigone of lateral ventricle: Junction of the anterior horn and posterior horn of lateral ventricle

 

Name From To
interventricular foramina (Monro) lateral ventricles third ventricle
cerebral aqueduct (Sylvius) third ventricle fourth ventricle
median aperture (Magendie) fourth ventricle subarachnoid space via the cisterna magna
right and left lateral aperture (Luschka) fourth ventricle subarachnoid space via the cistern of great cerebral vein

Ventricles

  • The four cavities of the human brain are called ventricles. 
  • The two largest are the lateral ventricles in the cerebrum; the third ventricle is in the diencephalon of the forebrain between the right and left thalamus; and the fourth ventricle is located at the back of the pons and upper half of the medulla oblongata of the hindbrain.
  • The ventricles are concerned with the production and circulation of cerebrospinal fluid lined by Ependymocytes
  • Floor of 4th ventricle (Rhomboid fossa)
  • It is diamond or rhomboidal shaped and is formed by posterior surface of pons (upper triangular part or pontine part) and dorsal surface of medulla (lower triangular part or medullary part) junction of pons and medulla forms intermediate part. Features of 4th ventricle are 😕
  1. Median sulcus (a midline groove) divides the floor into two symmetrical halves.
  2. Medial eminence is present an each side of median sulcus. It presents facial colliculus formed by genu (recurving fibers) of facial nerve looping around abducent nucleus. Facial colliculus lies in pons (i.e. in pontine part of floor).
  3. Hypoglossal triangle overlying hypoglossal nucleus and vagal triangle overlying dorsal nucleus of vagus. Both of these triangle lie in the medulla (medullary part of floor).
  4. Vestibular area overlies vestibular nuclei, partly in pons and partly in medulla.
  5. Sulcus coeruleus, a bluish area due to presence of pigmented neurons containing substantia ferruginea.
  6. Superior and inferior favea.
  • Infundibulum ,Mammillary body & Optic chiasma are seen in floor of 3rd ventricles

Lateral ventricle

  • Two lateral ventricles are the cavities of cerebral hemisphere (one in each hemisphere). Each lateral ventricle communicates with third ventricle through interventricular foramen of Monro.

It is divisile into four parts 😕

1. Central part (body) : It is located in the medial parts of frontal and parietal lobes. It extends from interventricular foramen (of Monro) in front to splenium of corpus callosum behind. It has choroid plexus. It has :- o Roof : Formed by corpus callosum.

  1. Floor : Formed form lateral to medial by caudate nucleus (body), stria terminalis, thalamostriate vein, and lateral part of upper surface of thalamus.
  2. Medial wall (partition between two lateral ventricles) : By septum pellucidum and body of fornix.
  • 2. Anterior horn : It lies in front of interventricular foramen of Monro extending into the frontal lobe. It has no choroid plexus. Its bondries are :-

  • Anterior : Posterior surface of genu and rostrum of corpus callosum.
  • Roof : Anterior part of trunk of corpus callosum.
  • Floor : Head of caudate nucleus and upper surface of rostrum of corpus callosum.
  • Medial (partition) : Septum pellucidum and column of fornix.
  • 3. Posterior horn : It lies behind splenium of corpus callosum and extends into occipital lobe. It may be variable in size (may be absent). It has no choroid plexus. Its boundries are :-

  1. Floor and medial wall : Bulb of posterior horn raised by forceps major and calcar avis, an elevation raised by calcarine sulcus (anterior part).
  2. Roof and lateral wall : Tapetum
  • 4. Inferior horn : It is the largest horn and extends into temporal lobe. It has choroid plexus. Its boundries are

  1. Roof and lateral wall : Tapetum, tail of caudate nucleus, stria terminalis and amygdaloid body.
  2. Floor : Collateral eminence (elevation by collateral sulcus) and hippocampus medially.

FUNCTION:

Flow of cerebrospinal fluid

  • The cerebrospinal fluid passes out through arachnoid villi into the venous sinuses of the skull.
  • The ventricles are filled with cerebrospinal fluid (CSF) which bathes and cushions the brain and spinal cord within their bony confines.
  • CSF is produced by modified ependymal cells of the choroid plexus found in all components of the ventricular system except for the cerebral aqueduct and the posterior and anterior horns of the lateral ventricles.
  • CSF flows from the lateral ventricles via the foramina of Monro into the third ventricle, and then the fourth ventricle via the cerebral aqueduct in the brainstem.
  • From the fourth ventricle it can pass into the central canal of the spinal cord or into the cisterns of the subarachnoid space via three small foramina: the central foramen of Magendie and the two lateral foramina of Luschka.
  • The fluid then flows around the superior sagittal sinus to be reabsorbed via the arachnoid villi (or granulation villi) into the venous sinuses, after which it passes through the jugular vein and major venous system.

Protection of the brain

Exam Question

  • Junction of the anterior horn and posterior horn of lateral ventricle is called as Trigone of lateral ventricle
  • Drainage of CSF from lateral to third ventricle is through Foramen of munro
  • Floor of 4th ventricle is formed by Sulcus limitans,Post. surface of pons & Post. surface of medulla
  •  Magendie foramen or the median aperture drains CSF from 4th ventricle to the cisterna magna
  • Fourth ventricle develops from Rhombencephalon
  • Infundibulum ,Mammillary body & Optic chiasma are seen in floor of 3rd ventricles
  • Abducens nuclei, hypoglossal nuclei, vestibular nuclei & Dorsal vagal nuclei are found in floor of fourth ventricles
  • Cerebral aqueduct (Duct of Sylvius) connects III ventricle to IV ventricle.
  • CSF is produced by modified ependymal cells of the choroid plexus
  • Floor of fourth ventricle is formed by rhomboidal fossa.
  • Ventricles of brain are lined by Ependymocytes
  • Anterior horn of lateral ventricle is closed anteriorly by the genu and rostrum of corpus callosum.
Don’t Forget to Solve all the previous Year Question asked on Ventricular system

Ventricular system

Ventricular system

Q. 1

Junction of the anterior horn and posterior horn of lateral ventricle is called as?

 A

Trigone of lateral ventricle

 B

Body of lateral ventricle

 C

Foramen of Monro

 D

Cerebral Aqueduct

Q. 1

Junction of the anterior horn and posterior horn of lateral ventricle is called as?

 A

Trigone of lateral ventricle

 B

Body of lateral ventricle

 C

Foramen of Monro

 D

Cerebral Aqueduct

Ans. A

Explanation:

Trigone of lateral ventricle

Trigone of the lateral ventricle is a triangular prominence of the floor of the lateral ventricle at the transition between occipital (posterior) and temporal (anterior) horn

The lateral ventricles connect to the central third ventricle through the interventricular foramen of Monro.


Q. 2

Drainage of CSF from lateral to third ventricle is through:

 A

Foramen of munro

 B

Foramen of lushka

 C

Foramen of magendi

 D

Aqueduct of sylvius

Q. 2

Drainage of CSF from lateral to third ventricle is through:

 A

Foramen of munro

 B

Foramen of lushka

 C

Foramen of magendi

 D

Aqueduct of sylvius

Ans. A

Explanation:

Foramen of munro


Q. 3

Magendie foramen or the median aperture drains CSF from which of the following structures to the cisterna magna?

 A

Lateral ventricle

 B

3rd ventricle

 C

4th ventricle

 D

Interpeduncular fossa

Q. 3

Magendie foramen or the median aperture drains CSF from which of the following structures to the cisterna magna?

 A

Lateral ventricle

 B

3rd ventricle

 C

4th ventricle

 D

Interpeduncular fossa

Ans. C

Explanation:

The median aperture (“Foramen of Magendie”) drains CSF from the fourth ventricle into the cisterna magna. Cisterna magna occupies the interval between inferior surface of cerebellum and posterior aspect of medulla oblongata.

The two lateral apertures (foramina of Luschka), one on the left and one on the right, are the primary routes for drainage of cerebrospinal fluid from the fourth ventricle into the cerebellopontine angle cistern. The foramen on axial images is posterior to the pons and anterior to the caudal cerebellum.


Q. 4

What is the junction of anterior horn and posterior horn of lateral ventricle called?

 A

Trigone of lateral ventricle

 B

Body of lateral ventricle

 C

Foramen of Monro

 D

Cerebral Aqueduct

Q. 4

What is the junction of anterior horn and posterior horn of lateral ventricle called?

 A

Trigone of lateral ventricle

 B

Body of lateral ventricle

 C

Foramen of Monro

 D

Cerebral Aqueduct

Ans. A

Explanation:

The lateral ventricle comprises a cavity within the telencephalon. It is divided into anterior horn, body, a posterior horn and an inferior horn. The junction between the body of lateral ventricle and its posterior and inferior horn is known as the atrium or collateral trigone. 

  • Bodies of the lateral ventricle are separated by paired septi pellucidi.
  • Choroid plexus of the lateral ventricle is located anteromedially in the body and superomedially in the temporal horn. The anterior horn and posterior horn do not contain elements of the choroid plexus.
  • Lateral ventricle communicate with the third ventricle via the paired foramina of Monro at the junction of anterior horn and body of the lateral ventricle inferiorly. 

Q. 5

Foramen of magendie, drains CSF from which midline structure and exits from it?

 A

Third ventricle

 B

Fourth ventricle

 C

Lateral ventricle

 D

All of the above

Q. 5

Foramen of magendie, drains CSF from which midline structure and exits from it?

 A

Third ventricle

 B

Fourth ventricle

 C

Lateral ventricle

 D

All of the above

Ans. B

Explanation:

Fourth ventricle is the last ventricle in the cerebellum, its T shaped roof has three apertures which communicates with the subarachonoid space. Foramen of magendi a median aperture is present doraslly in the roof, it communicates with the cisterna magna. Foramen of luschka is a lateral aperture which is present on right and left side. It drains into the cerebellopontine angle cistern.


Q. 6

Fourth ventricle develops from?

 A

Telencephalon

 B

Mesencephalon

 C

Diencephalon

 D

Rhombencephalon

Q. 6

Fourth ventricle develops from?

 A

Telencephalon

 B

Mesencephalon

 C

Diencephalon

 D

Rhombencephalon

Ans. D

Explanation:

Lateral ventricle develops from the cavity of telencephalon. Third ventricle develops from diencephalon. Cavity of mesencephalon remains narrow and forms the aqueduct, while the cavity of rhombencephalon forms the fourth ventricle.


Q. 7

Which of the following foramen is responsible for the drainage of CSF from lateral to third ventricle?

 A

Foramen of Monro

 B

Foramen of Luschka

 C

Foramen of Magendie

 D

Cerebral aqueduct

Q. 7

Which of the following foramen is responsible for the drainage of CSF from lateral to third ventricle?

 A

Foramen of Monro

 B

Foramen of Luschka

 C

Foramen of Magendie

 D

Cerebral aqueduct

Ans. A

Explanation:

The two interventricular foramens, or foramens of Monro, are apertures between the column of the fornix and the anterior end of the thalamus. The two lateral ventricles communicate with the third ventricle through these foramens and drainage of CSF occurs.

 
The lateral aperture (foramen of Luschka) is the opening of the lateral recess into the subarachnoid space near the flocculus of the cerebellum. A tuft of choroid plexus is commonly present in the aperture and partly obstructs the flow of CSF from the fourth ventricle to the subarachnoid space. 
 
The medial aperture (foramen of Magendie) is an opening in the caudal portion of the roof of the ventricle. Most of the outflow of CSF from the fourth ventricle passes through this aperture.
 
The cerebral aqueduct is a narrow, curved channel running from the posterior third ventricle into the fourth.
 
Ref: Waxman S.G. (2010). Chapter 11. Ventricles and Coverings of the Brain. In S.G. Waxman (Ed), Clinical Neuroanatomy, 26e.

Q. 8

Floor of 4th ventricle is not formed by ?

 A

Sulcus limitans

 B

Anterior medullary velum

 C

Posterior surface of pons

 D

Posterior surface of medulla

Q. 8

Floor of 4th ventricle is not formed by ?

 A

Sulcus limitans

 B

Anterior medullary velum

 C

Posterior surface of pons

 D

Posterior surface of medulla

Ans. C

Explanation:

Floor of the fourth ventricle is not formed by Anterior medullary velum.Anterior medullary velum forms the roof.All the other options are associated with the floor of the ventricle.
 
Fourth ventricle: It is a tent like structure, it is situated in front of the cerebellum and behind the pons and upper half of the medulla oblongata. It is lined by ciliated epithelium.
 
Communications:
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).
 
Boundries:
 
1. Roof consists of
  • Upper portion of roof: The superior peduncle and the anterior medullary velum; 
  • Lower portion of roof: The posterior medullary velum, the epithelial lining of the ventricle covered by the tela chorioidea inferior and the taeniae of the fourth ventricle.
2. Floor:
  • Upper part :Fascial colliculus on the dorsal surface of pons.
  • Intermediate part:Vestibular nuclei medulllary striae.
  • Lower part:Upper part of medulla oblongata containing hypoglossal and vagal triangles.
3. Laterally: bounded by superior and inferior cerebellar peduncles,gracile tubercle and cuneate tubercle.
 
Apertures: Through these, the CSF leaves the fourth ventricle to the subarachnoid space
  • One median foramen (foramen of Magendie): in the lower part of the inferior medullary velum.
  • Two lateral foramens (foramens of Lushka): one in each lateral recess.
Ref:
1. Color atlas of neuroscience: neuroanatomy and neurophysiology, By Ben Greenstein, Adam. Greenstein, Page 16
2. BD Chaurasia’s Human Anatomy,Volu III, 4Th edition, Page 397

Q. 9

All are seen in the floor of 3rd ventricle except?

 A

Infundibulum

 B

Oculomotor nerve

 C

Mammillary body

 D

Optic chiasmaFourth Ventricle

Q. 9

All are seen in the floor of 3rd ventricle except?

 A

Infundibulum

 B

Oculomotor nerve

 C

Mammillary body

 D

Optic chiasmaFourth Ventricle

Ans. B

Explanation:

B i.e. Occulomotor Nerve 


Q. 10

True about 4thventricle is-

 A

Rhomboid fossa forms floor

 B

Choroid plexus lies at its floor

 C

Connection between two cerebral hemispheres

 D

Lies inferior to inferior cerebellar peduncle

Q. 10

True about 4thventricle is-

 A

Rhomboid fossa forms floor

 B

Choroid plexus lies at its floor

 C

Connection between two cerebral hemispheres

 D

Lies inferior to inferior cerebellar peduncle

Ans. A

Explanation:

A i.e., Rhomboid fossa forms the floor


Q. 11

Which nucleus is not found in the floor of the fourth ventricle

 A

Abducens N

 B

Dorsal vagal nuclei

 C

Dorsal vagal nuclei

 D

None

Q. 11

Which nucleus is not found in the floor of the fourth ventricle

 A

Abducens N

 B

Dorsal vagal nuclei

 C

Dorsal vagal nuclei

 D

None

Ans. D

Explanation:

D i.e., None


Q. 12

Cerebral aqueduct (Duct of Sylvius) – which is true:

 A

3 cms in length

 B

Connects III. ventricle to IV ventricle

 C

Connects III. ventricle to IV ventricle

 D

Connects two lateral ventricles

Q. 12

Cerebral aqueduct (Duct of Sylvius) – which is true:

 A

3 cms in length

 B

Connects III. ventricle to IV ventricle

 C

Connects III. ventricle to IV ventricle

 D

Connects two lateral ventricles

Ans. B

Explanation:

B i.e., Connects HI ventricle to IV ventricle

Rhomboid fossa or floor of 4th ventricle has abducent motor nucleus, dorsal motor nucleus of vagus, hypoglossal nucleus, and facial nucleus.

– 4th ventricle communicates through cerebral aqueduct of sylvius with 3rd ventricle.


Q. 13

CSF is principally secreted by ‑

 A

Choroid plexus

 B

Arachnoid granulation

 C

Floor of fourth ventricle

 D

Periaqueductal grey

Q. 13

CSF is principally secreted by ‑

 A

Choroid plexus

 B

Arachnoid granulation

 C

Floor of fourth ventricle

 D

Periaqueductal grey

Ans. A

Explanation:

A i.e. Choroid plexus


Q. 14

Obstruction to the flow of CSF at the aqueduct of sylvius will most likely lead to enlargement of ‑

 A

All of the ventricles

 B

Only lateral ventricle

 C

Only fourth ventricle

 D

Both lateral and third ventricles

Q. 14

Obstruction to the flow of CSF at the aqueduct of sylvius will most likely lead to enlargement of ‑

 A

All of the ventricles

 B

Only lateral ventricle

 C

Only fourth ventricle

 D

Both lateral and third ventricles

Ans. D

Explanation:

Ans. is `d’ i.e., Both lateral and third ventricle

o CSF is produced by choroid plexus in the lateral and III ventricles. Then it flows through the aqueduct ofsylvius into the 4th ventricle and from there into the subarachnoid space to be absorbed by the arachnoid villi.

o Obviously any obstruction in the aqueduct of sylvius will lead to enlargement of the proximal ventricles (i.e. both lateral and HP’ ventricles).


Q. 15

Floor of 4th ventricle has ‑

 A

Infundibulum

 B

Vagal triangle

 C

Mammillary body

 D

Tuber cincrium

Q. 15

Floor of 4th ventricle has ‑

 A

Infundibulum

 B

Vagal triangle

 C

Mammillary body

 D

Tuber cincrium

Ans. B

Explanation:

Floor of 4th ventricle (Rhomboid fossa)

  • It is diamond or rhomboidal shaped and is formed by posterior surface of pons (upper triangular part or pontine part) and dorsal surface of medulla (lower triangular part or medullary part) junction of pons and medulla forms intermediate part. Features of 4th ventricle are :‑
  1. Median sulcus (a midline groove) divides the floor into two symmetrical halves.
  2. Medial eminence is present an each side of median sulcus. It presents facial colliculus formed by genu (recurving fibers) of facial nerve looping around abducent nucleus. Facial colliculus lies in pons (i.e. in pontine part of floor).
  3. Hypoglossal triangle overlying hypoglossal nucleus and vagal triangle overlying dorsal nucleus of vagus. Both of these triangle lie in the medulla (medullary part of floor).
  4. Vestibular area overlies vestibular nuclei, partly in pons and partly in medulla.
  5. Sulcus coeruleus, a bluish area due to presence of pigmented neurons containing substantia ferruginea.
  6. Superior and inferior favea.

Q. 16

Anterior horn of lateral ventricle is closed anteriorly by –

 A

Thalamus

 B

Septum pellucidum

 C

Lamina terminalis

 D

Corpus callosum

Q. 16

Anterior horn of lateral ventricle is closed anteriorly by –

 A

Thalamus

 B

Septum pellucidum

 C

Lamina terminalis

 D

Corpus callosum

Ans. D

Explanation:

Anterior horn of lateral ventricle is closed anteriorly by the genu and rostrum of corpus callosum.

Lateral ventricle

Two lateral ventricles are the cavities of cerebral hemisphere (one in each hemisphere). Each lateral ventricle communicates with third ventricle through interventricular foramen of Monro.

It is divisile into four parts :‑

1) Central part (body) : It is located in the medial parts of frontal and parietal lobes. It extends from interventricular foramen (of Monro) in front to splenium of corpus callosum behind. It has choroid plexus. It has :- o Roof : Formed by corpus callosum.

  1. Floor : Formed form lateral to medial by caudate nucleus (body), stria terminalis, thalamostriate vein, and lateral part of upper surface of thalamus.
  2. Medial wall (partition between two lateral ventricles) : By septum pellucidum and body of fornix.

2) Anterior horn : It lies in front of interventricular foramen of Monro extending into the frontal lobe. It has no choroid plexus. Its bondries are :-

  • Anterior : Posterior surface of genu and rostrum of corpus callosum.
  • Roof : Anterior part of trunk of corpus callosum.
  • Floor : Head of caudate nucleus and upper surface of rostrum of corpus callosum.
  • Medial (partition) : Septum pellucidum and column of fornix.

3) Posterior horn : It lies behind splenium of corpus callosum and extends into occipital lobe. It may be variable in size (may be absent). It has no choroid plexus. Its boundries are :-

  1. Floor and medial wall : Bulb of posterior horn raised by forceps major and calcar avis, an elevation raised by calcarine sulcus (anterior part).
  2. Roof and lateral wall : Tapetum

4) Inferior horn : It is the largest horn and extends into temporal lobe. It has choroid plexus. Its boundries are

  1. Roof and lateral wall : Tapetum, tail of caudate nucleus, stria terminalis and amygdaloid body.
  2. Floor : Collateral eminence (elevation by collateral sulcus) and hippocampus medially.

Q. 17

Ventricles of brain are lined by ‑

 A

Ependymocytes

 B

Astrocytes

 C

Oligodendrocytes

 D

Podocytes

Q. 17

Ventricles of brain are lined by ‑

 A

Ependymocytes

 B

Astrocytes

 C

Oligodendrocytes

 D

Podocytes

Ans. A

Explanation:

Ventricles of brain are lined by ependyma (ependymocytes).

Ventricles of brain

These are cavities in the brain lined by ependyma and filled with CSF.

They contain choroid plexuses wich secrete CSF.

These are four fluid filled intercommunicating cavities within the brain :-

i) Two lateral ventricles (right and left),

ii) Third ventricle, and

iii) Fourth ventricle. o Lateral ventricle communicates with third ventricle by interventricular foramen (foramen of Monro).

Third ventricle communicates with fourth ventricle by cerebral aqueduct (aqueduct of sylvius).

Fourth ventricle communicates with subarachnoid space by a median foramen (Mangendie) and two lateral (Luschka) foramina.




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