Lecture 20 - Meninges, ventricular system, structure and layout of the main brain structures

Question 1

Meninges

Answer 1

Protective covering for the brain and spinal cord

3 layers of protective coverings between the cranium, the bone of the skull and the brain//spinal cord, vertebrae

Question 2

Meningitis

Answer 2

Inflammation of the meninges

Question 3

Three layers of the meninges

Answer 3

Dura mater, arachnoid mater and pia mater

Question 4

Dura mater

Answer 4

Outermost layer of the meninges
Dense and fibrous - tough (first layer of protection - for example if a person got a cranial fracture, the little sharp pieces of bone could potentially damage the brain therefore this is very thick in order to prevent damage to the brain
Two layers - outer and inner
Space between the layers forms venous sinuses - only in some places
Inner layer forms the dural folds
Translates to - tough mother

Question 5

Venous sinuses

Answer 5

Located where the two layers of the dura mater seperate
Collecting veins
They collect venous blood from the brain and old CSF after it has cycled through the entire ventricular system

Question 6

Dural folds

Answer 6

Formed from the inner layer of the dura mater
Seperate major divisions of the brain
Provide stability of the brain within the cranium (stabilises the position of the brain)

Sometimes called dural reflections

Question 7

Three dural folds

Answer 7

Falx cerebri, falx cerebelli and tentorium cerebelli

Note that falx means sickle shaped

Question 8

Falx cerebri

Answer 8

Dural fold
Separates cerebral hemispheres
In the media plane (seperates it into two halves)
Sickle shaped piece of tissue that foes between the two halves of the cerebrum

Question 9

Falx cerebelli

Answer 9

Dural fold
Separates cerebellar hemispheres
In the median plane

Question 10

Tentorium cerebelli

Answer 10

Dural fold
Separates the cerebrum from the cerebellum
In the horizontal plane
Gap between the cerebrum and cerebellum, fits in-between this space and separates these two structures

Question 11

Arachnoid mater

Answer 11

Spider like mother
Layer beneath the dura mater and above the Pia mater
Named because it has a spider-like appearance
Does not extend into sulci (valleys)
Contains two special features - the subarachnoid space and arachnoid granulations
Contains blood vessels (within the subarachnoid space, lying on top of Pia mater)

Directly under the dura mater, little ‘legs’ that creates a space between the arachnoid and the Pia mater

Question 12

Subarachnoid space

Answer 12

Between the arachnoid and the Pia mater
Filled with CSF - which provides It with a cushioning like feature around the CNS that protects it
Also contains the blood vessels

Question 13

Arachnoid granulations

Answer 13

Perforate the inner layer of the dura mater
Transport ‘old’ CSF from subarachnoid space into venous sinus - pierce through the inner layer of the dura mater and can shunt the CSF in the subarachnoid space out into the venous sinus (one way flow so that it can go out into the venous blood and drained from the head.

Question 14

Pia mater

Answer 14

Inner layer of the meninges
Transparent and delicate
Blood vessels in arachnoid sit on top of the Pia mater
Adheres to brain and follows gyri and extends into sulci (only layer that does this)
Adhered closely to surface of brain
Delicate mother

Question 15

The meninges of the spinal cord

Answer 15

Has the same three layers as the brain (dura mater, arachnoid mater and Pia mater)
Meninges also covers the spinal cord because it is a part of the CNS
Again the dura mater prevents sharp bits of bone when the vertebrae are damaged from piercing and injuring the spinal cord

Question 16

Features of the ventricular system

Answer 16

Network of interconnected “spaces” (=ventricles) within the brain
Filled with CSF which nourishes and protects the brain
Spaces line with ependymal cells which circulate the CSF (waving cilia) (these cells do not manufacture the CSF, they propel the circulation of CSF through the ventricular system)
CSF is produced by the choroid plexus, a special tissue present on each of the ventricles

Question 17

The ventricular system

Answer 17

Lateral ventricles (2) 
Third ventricle (1) 
Cerebral aqueduct (1) 
Fourth ventricle (1) 
Central canal (spinal cord)

Question 18

Lateral ventricles

Answer 18

Two of them

One in each cerebral hemisphere

Question 19

Third ventricle

Answer 19

Located in the diencephalon (at the midline of the brain)
One ventricle
Small hole and brain tissue runs through the tiny hole in-between

Question 20

Cerebral aqueduct

Answer 20

Connects third ventricle to the fourth ventricle
Located in the midbrain
One ventricle

Question 21

Fourth ventricle

Answer 21

Located at the level of the cerebellum

One ventricle

Question 22

Central canal

Answer 22

Goes down into the spinal cord

Question 23

Cerebrospinal fluid

Answer 23

Surrounds the CNS within the subarachnoid space
Provides support and cushioning
Transports nutrients and waste
Produced by choroid plexus within the ventricles

Question 24

CSF circulation path

Answer 24

Start at the lateral ventricles - third ventricle - cerebral aqueduct - 4th ventricle - subarachnoid space and within the subarachnoid space it flows around the brain and spinal cord - exits through arachnoid granulations into venous sinus (between hemispheres)

Question 25

CSF circulates around the brain in which layer of the meninges

Answer 25

arachnoid

Question 26

Old/used CSF is transported into the venous circulation through which strcuture…

Answer 26

Arachnoid granulations - things that pole through into the venous sinus

Question 27

The third ventricle is located with which brain region…

Answer 27

Diencephalon

Question 28

How does the CSF pass into the venous sinus?

Answer 28

The arachnoid mater has projections called arachnoid granulations. These project through the inner layer of dura mater. CSF moves from subarachnoid space to venous sinus