BMC L4

Question 1

What are the meninges?

Answer 1

3 layers of protective tissue:

Dura mater
Arachnoid mater
Pia mater

Surrounding the brain + spinal cord.
Meninges of brain + spinal cord connected via magnum foramen

Question 2

Describe the position of the dura mater

Answer 2

Most superior of the meninges - outermost layer

Question 3

Describe the structure and function of the dura mater

Answer 3

dura mater = hard mother
dura - durable

-2 layers:
-fibrous outer layer - fibrous because containds collagen - fibrous layer fuses with endosteum
-smooth meningeal inner layer

Fibrous outer layer makes it tough + inflexible, therefore, this allows it to protect the brain from displacement

Question 4

Epidural Space

Answer 4

Potential space between dura mater of spinal cord and wall of vertebral column. Contains
-arteries
-lymphatics
-fatty tissue

Question 5

Describe the position of the arachnoid mater

Answer 5

Middle layer of meninges

Question 6

State the function of the arachnoid mater

Answer 6

Arachnoid mater has projections which project into the sinuses of the dura mater, called arachnoid granulations / arachnoid villi

These transfer CSF from ventricles into blood (CSF ABSORPTION)

Question 7

Subarachnoid Space

Answer 7

Space between arachnoid mater and pia mater
Filled with CSF
All blood vessels + cranial nerves which enter the brain run through the subarachnoid space

arachnoid - blood vessels run through similar to shape of “spider web”

Question 8

Describe the location and function of the Pia Mater

Answer 8

Inner most layer of meninges - soft

Adheres closely to the brain and runs through into sulci + fissues of cortex

It then projects into ventricles

Then fuses with ependyma

Ependyma is a membronous lining of the ventricles

Forms choroid plexi - (where ependyma and pia mater meet)

Which produce CSF

Question 9

Diagram of meninges

Answer 9

1. Skin of Scalp
2. Perosteum
3. Bone of skull
4. Dura mater - both layers
5. Subdural space
6. Arachnoid mater
7. Arachnoid villus
8. Subarachnoid space
9. Pia mater

Question 10

Where is cerebrospinal fluid produced

Answer 10

Produced by choroid plexi in ependyma of ventricles of brain

Question 11

Where is cerebrospinal fluid found?

Answer 11

In ependyma, membraneous lining in ventricles of brain

Subarachnoid space

Central canal, a space within the spinal cord

Question 12

Functions of CSF

Answer 12

1. Cushions brain + spinal cord
2. Supplies nutrients to brain + spinal cord + removes waste

CLEAR LIQUID, IT IS A FILTRATE OF BLOOD, produced by filtering blood

Question 13

Why is CSF similar to saliva?

Answer 13

Filtrate of blood (both produced by filtering blood)

Question 14

CSF circulation

Answer 14

Lateral ventricle choroid plexus - CSF - Lateral ventricle

INTRAVENTRICULAR FORAMEN

3rd ventricle choroid plexus - CSF - 3rd ventricle

CEREBRAL AQUADUCT

4th Ventricle choroid plexus - CSF - 4th ventricle

LATERAL + MEDIAL APERTURES
Subarachnoid space

Arachnoid Villi

Heart Lungs

REFER TO DIAGRAM L4

Question 15

What is glymphatics

Answer 15

Drainage system of the brain

Question 16

Explain how glymphatics works as a drainage system of the brain

Answer 16

1. AQP4 channels between astrocyte end feet + blood vessels carry CSF into parenchyma
2. In parenchyma, CSF mixes with intersititual fluid (ISF)
3. This mixture, is known as the drainage system of the brain
4. This mixture of CSF and ISF enters the perivascular space which surrounds the veins
5. It removes waste (drains the waste), e.g. beta amyloid peptide

Question 17

What affect does sleep have on glymphatics

Answer 17

More CSF enters the glymphatic system during sleep

Question 18

Give 2 special features of ependymal cells

Answer 18

1. Rich blood supply
2. Modified ependymal cells pump Na+, H2O, folllowed by osmosis

Question 19

Subdural space

Answer 19

Potential space between dura mater and arachnoid mater

Question 20

The cranial cavity

Answer 20

The cranial cavity is the skull / crainium
It is a rigid box
It consists of blood vessels, CSF, brain

Question 21

How does the cranial cavity communicate with the vertebral column?

Answer 21

Via the foramen magnum

Question 22

Intracranial pressure

Answer 22

• If extensive bleedig, excessive tumout growth in cranial cavity, this leads to increased intracranial pressure
  -This is because cranial caivity is a rigid box
  -Not enough space for growth

Question 23

What is the blood brain barrier?

Answer 23

BBB

Highly selective permeable barrier between circulating blood + extracellular CNS fluid

Formed by blood capillary endothelial cells - joined together by tight junctions

Question 24

Function of BBB

Answer 24

Restrict filtration of materials into CSF by choroid plexi

including

-bacteria
-toxins
-drugs

Question 25

What is the BBB made of?

Answer 25

1. Blood capillary endothelial cells
2. Basement membrane
3. Feet of astrocytes (wrap around capillaries)

Question 26

What are the 4 levels of protection of brain?

Answer 26

1. Skull / Cranial Cavity / Cranium
2. Meninges
3. Blood Brain Barrier
4. Cerebrospinal Fluid

Question 27

Circumventricular organs

Answer 27

• Not protected by BBB
  -interact directly with peripheral blood

if we monitor blood chemistry, we see hormone released from circumventricular organs to blood stream

Question 28

Two examples of circumventricular organs

Answer 28

-pituitary gland
-pineal gland