Lesson 3 - Ventricles and CSF Flashcards by Lauren Carroll

What is the ventricular system in the brain?

The ventricular system consists of fluid filled interconnected spaces within the brain called ventricles

It is a continuation of the central spinal canal.

These ventricles consist of 2 lateral ventricles, the 3rd ventricle and the 4th ventricle and they are connected via narrow canals

This system functions to produce, transport and remove CSF.

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What is CSF?

Cerebrospinal Fluid

It has a protective, excretory, endocrine (carries hormones), nourishment (carries vitamins) and buoyancy, immunological and shock absorbing function

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The ventricles are internal cavities in the brain filled with ——- ———- ———–

The ventricles are connected

cerebrospinal fluid

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Development of the brain

During embryonic development, the rostral portion of the ———–
——–s undergoes significant growth and differentiation to form the brain.

By week 5, the primary brain vesicles (———–, ———— and ———–) can be identified

neural tubes
prosencephalon, mesencephalon and rhombencephalon

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Development of the brain

By week 7, five secondary brain vesicles are produced by division of prosencephalon (———–, ————) and the rhombencephalon (————, ————-)

telencephalon, diencephalon

metencephalon, myelencephalon)

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Development of the ventricles

The neural canal dilates within the prosencephalon, leading to the formation of the ——– ventricles (Telen) and ——- ventricle (Dien).

The dilation of the neural canalwithin the rhombencephalonforms the ——— ventricle.

The cavity of the mesencephalon or midbrain forms the ——– ————

lateral
fourth
third
cerebral aqueduct

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Development of the brain

Developmentally, the brain consists of 3 regions: forebrain, midbrain, hindbrain:

The forebrain region of the developing brain forms from the —————-

The midbrain (mesencephalon) arises from the ———- vesicle of the neural tube

The hindbrain arises from the developing ——————

The metencephalon develops into the pons and the overlying cerebellum

The myelencephalon develops into the ———- ———–

The midbrain, pons and medulla oblongata form the ————-

prosencephalon
second
rhombencephalon
medulla oblongata
brainstem

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The forebrain region of the developing brain forms from the prosencephalon, which includes;
the —————, which contains the cerebral hemispheres (cerebrum)
the ————, which contains the thalamus, hypothalamus.

telencephalon
diencephalon

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The midbrain (mesencephalon) arises from the ——— vesicle of the neural tube, while the interior of this portion of the tube becomes the ———- ————-.

second
cerebral aqueduct

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The hindbrain arises from the developing ————– and consists of the cerebellum, pons, and medulla

rhombencephalon

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Development of the ventricles

The ventricular system in the brain develops froma single cavity, i.e. ——— of the neural tube. The neural tube is formed around the fourth week of gestation.

In the spinal cord, this is represented by the ——— and insignificant central canal.

The neural canal dilates within the prosencephalon, leading to the formation of the ——– ventricles (Telen) and ——– ventricle (Dien).

The dilation of the neural canalwithin the ————-forms the fourth ventricle.

The cavity of the mesencephalon forms the ———- ———-

lumen
vestigial
lateral
third
rhombencephalon
cerebral aqueduct

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Topography of the ventricular system

4th Ventricle

The central canal moves more dorsal as it passes from spinal cord to ——- ——– and opens out into the 4th ventricle which lies on the dorsal surface of the brain beneath the ———– (forms the roof of 4th ventricle for most part).

brain stem
cerebellum

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4th ventricle is a wide and shallow ————– -shaped depression.

diamond (rhomboid)

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On each side of the 4th ventricle, a lateral recess extends towards the lateral margin of the brain stem and is in continuity with the subarachnoid space of the ————– angle via the foramen of ———- (lateral aperture).

cerebellopontine
Luschka

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The 4th ventricle extends rostrally as far as the ————– junction where it becomes continuous with the cerebral aqueduct.

pontomesencephalic

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The 4th ventricle

The ———— ———— passes throughout the length of the midbrain, beneath the inferior and superior colliculi.

cerebral aqueduct

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At the rostral margin of the midbrain, the cerebral aqueduct opens into the —— ventricle.

3rd

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Lateral walls of the 3rd ventricle are formed by ———– and ————- on either side

thalamus
hypothalamus

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Roof of 3rd ventricle formed by —- ————–

pia-ependyma

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In the rostral part of 3rd ventricle lies an aperture, the interventricular foramen (foramen of ———–), which is located between the column of the ———- and the anterior pole of the thalamus.

monroe
fornix

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Remember the ——— ———–facilitates communication with the 4th ventricle.
And the ———– ———- facilitates communication on either side with the lateral ventricle in the cerebral hemisphere.

cerebral aqueduct
interventricular foramen

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The lateral ventricle is — shaped

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The lateral ventricle consists of an ——— (frontal) horn, body, ——— (occipital) horn and ———-(temporal) horn.

anterior
posterior
inferior

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The anterior horn of the lateral ventricle is that part anterior to the ————- ———–

interventricular foramen

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Lateral wall of lateral ventricle = head of the ----------- -----------

caudate nucleus

Roof of lateral ventricle = --------- --------

corpus callosum

Medial wall = ---------- ----------- This sheet spans between the corpus callosum and fornix in the midline and separates the anterior horns of the 2 lateral ventricles

septum pellucidum.

Body of lateral ventricle extends behind the interventricular foramen with its floor as ------------- and tail of ------ ------------

thalamus caudate nucleus.

The inferior horn lies in the ------------- lobe and in its floor lies the ---------- while in its roof runs lies the tail of the caudate nucleus.

temporal hippocampus

Remember the 2 lateral ventricles communicate with 3rd ventricle via the ------------ ----------

interventricular foramen.

The Third and Fourth ventricles are bounded by the ---------- and ----------

thalamus and hypothalamus

the narrow slit-like 3rd ventricle is connected to the fourth ventricle by the ---------- ----------- (---------- of --------)

cerebral aqueduct aqueduct of sylvius

The tent-like fourth ventricle is continuous with the narrow central canal of the spinal cord and through the three foramina in its roof with the subarachnoid space. It's located behind the -------------- ---------------- and the pons, anterior to the cerebellum

medulla oblongata

The foramina of the 4th ventricle are called the foramen of -------- x2 (Lateral) and -------------- x1 (Posterior)

Lushka and Magendie

The central canal of the spinal cord has a small dilation at its inferior end the ----------- ventricle

terminal

2 lateral ventricles communicate with the third ventricle through the ------------- foramen of -----------

interventricular foramen of Monro

Roof of the lateral ventricles is under the surface of the ----------- --------

corpus callosum

The floor of the lateral ventricles is the body of the ------------- -------- and the lateral margin of the --------

caudate nucleus thalamus

The medial wall of the lateral ventricles is the ---------- ---------- anteriorly

septum pellucidum

Foramen of the lateral ventricles is bounded anteriorly by the anterior column of the ------- and posteriorly by the anterior end of the ------------

fornix thalamus

The ---------- ---------- of the lateral ventricles projects into the body of the ventricle

choroid plexus

What colour is the CFS?

Colourless Any colour is abnormal eg. subarachnoid haemorrhage or blood contamination during spinal tap

The CSF contains inorganic -------s similar to those in blood plasma (0.3%), glucose, protein, and ------------s

salts lymphocytes

CFS pressure is kept -------- 8-15 mmHg

constant

What is the total volume of CSF?

Usually 135-150 ml

What is the functions of CSF?

Protection Buoyancy Excretion of waste products Endocrine medium for the brain

The CSF protects the brain from damage by '-----------' the brain

buffering

CSF and Buoyancy: Immersion in fluid reduces the net ------- of the brain from about 1,400 gm to about 50gm Pressure at the ----- of the brain is reduced concussion

weight base

How the CSF excrete waste products?

the one-way flow of CSF to the blood takes potentially harmful metabolites, drugs and other substances away from the brain

How does CSF act as an endocrine medium for the brain?

The CSF serves to transport hormones to other areas of the brain. Hormones released into the CSF can be carried to remote sites of the brain where they may act.

What does a high level of proteins in the CSF indicate?

indicative of meningitis and multiple sclerosis

Where is most CSF formed?

in the choroid plexuses of the lateral, third, and fourth ventricles

What is the choroid plexus?

where most CFS in formed in the lateral, third and fourth ventricles Cuboidal epithelial cells (ependyma) surrounding a core of capillaries and loose connective tissue much folded

Some CSF originates from ---------- cells that line the ventricles

ependymal

How much CSF does the choroid plexus produce a day?

Around 500ml

Why is the CSF recycled 4 times a day?

to remove metabolites and toxins like beta amyloid (plaques that cause Alzheimer's)

Large amounts of CSF are drained primarily into the ---------

blood

Most CSF is produced by the ----------- ------------ of the ------------- ventricle

choroid plexus lateral ventricle

Describe the flow of the CSF

Most CSF is produced by the choroid plexus of the lateral ventricle  From here, it flows into the interventricular foramen into the 3rd ventricle. From the 3rd ventricle, it enters the 4th ventricle via the cerebral aqueduct  CSF leaves the ventricular system via the 3 apertures of the 4th ventricle (i.e. 2 Lateral apertures (foramen of Luschka), median aperture(foramen of Magendie)) enters the subarachnoid space. Most CSF enters cisterna magna via median aperture, but some enters the subarachnoid space via lateral apertures.  From here, CSF flows superiorly around the cerebral hemispheres to the sites of reabsorption

CSF is reabsorbed into the venous system by passing into the ----- venous sinuses, mainly the -------- ---------- sinus.

dural superior sagittal

----------- -------- can be found along the dural venous sinuses which are formed by invaginations of the arachnoid mater through the dural wall and into the lumen of the venous sinus.

Arachnoid villi

Why does the reabsorption of CSF occur by passing into the dural venous sinuses (mainly the superior sagittal sinus)?

Reabsorption occurs here because the hydrostatic pressure in the subarachnoid space is higher than that in the lumen of the sinus and because of the greater colloid osmotic pressure of blood compared to CSF

What is Hydrocephalus?

swelling of the ventricles (AKA fluid build-up in brain)

When does Hydrocephalus occur?

1. The flow of CSF is obstructed. This usually presents as non-communicating hydrocephalus when there is an obstruction between the subarachnoid space and the ventricles. Can be caused by tumours or adhesions following head trauma or infection 2. There is overproduction of CSF which can be caused by CSF infection, choroid plexus hypertrophy or tumor 3. There are issues with CSF absorption – usual presents as communicating hydrocephalus, This can present during laparoscopic surgery involving insufflation of a gas (usually carbon dioxide) into the peritoneal cavity producing a pneumoperitoneum causing an increase in intra-abdominal pressure (IAP). 4. There is a congenital abnormality

Name some symptoms of Hydrocephalus

headaches, unsteadiness, mental impairment. Papilloedema can occur which is swelling of the optic disks and can result in blindness

Name the treatment for Hydrocephalus

Decompression of dilated ventricles by inserting a shunt connecting the ventricles and the jugular vein or the abdominal peritoneum.