Week 1: Lecture 3- Meninges and ventricles

Question 1

What are the 3 meningeal layers that surround the CNS?

Answer 1

1. Dura matter (outer)
2. Arachnoid mater (middle)
3. Pia mater (inner)

Question 2

Which artery supplies dura mater?

Answer 2

middle meningeal artery

Question 3

Which layer is below the skin and above the dura mater?

Answer 3

cranium

Question 4

What are each of the 3 meningeal layers like?

Answer 4

1. dura - tough, fibrous, protective layer
2. arachnoid- thin, delicate, spiders-web like, vascular
3. pia - microscopically thin, follows gyri and Sulci

Question 5

what are the two layers of dura mater?

Answer 5

1. periosteal dura mater

2. meningeal dura mater

Question 6

What is the periosteal dura mater layer tightly adhered to?

Answer 6

skull

Question 7

What is the meningeal dura mater layer tightly adhered to?

Answer 7

arachnoid mater

Question 8

Where is CSF found?

Answer 8

sub-arachnoid space between the arachnoid and Pia mater

Question 9

What is a dural fold?

Answer 9

At some areas, the inner dural layer (meningeal) separates from the outer dural layer (periosteal) and protrude int he cranial cavity forming double layered dural folds

Question 10

What are the 3 dural folds called and where are they found?

Answer 10

1. falx cerebri - located between the two hemispheres
2. tentorium cerebelli - seperates cerebral hemispheres from the cerebellum
3. falx cerebelli - separates two cerebellum

Question 11

What is the falx cerebri attached to anteriorly and posteriorly?

Answer 11

anterior - crista Galli of the ethmoid bone

posterior - internal occipital protuberance

Question 12

What is a sinus?

Answer 12

a channel

venous blood from brain and CSF travels through these channels

Question 13

What are the names of the important dural venous sinuses?

Answer 13

• inferior sagittal sinus
• superior sagittal sinus
• straight sinus
• confluence of sinuses
• right transverse sinus
• sigmoid sinus
• cavernous sinus

Question 14

Which sinus is formed from the falx cerebri?

Answer 14

superior sagittal sinus

Question 15

What are denticulate ligaments?

Answer 15

projections from the Pia mater that attaches the spinal cord to the arachnoid mater, through the arachnoid mater and into the dura
function is to secure spinal cord on either side

Question 16

What is between the bone and the dura?

Answer 16

epidural space

Question 17

Which of the following are real spaces and which are potential spaces?

1. between the dura and the skull
2. between the dura and the arachnoid
3. subarachnoid space
4. epidural space

Answer 17

1. potential
2. potential
3. real - as it has blood vessels, CSF etc
4. real - as it has fat inside

Question 18

What is the space between the dura and the arachnoid?

Answer 18

subdural space - very thin potential space

Question 19

what’s the difference between dura mater in the cranium and in the spine?

Answer 19

in the spine, dura mater has no periosteal component, just meningeal

Question 20

What is CSF?

Answer 20

• blood derived
• clear, colourless fluid
• contains glucose and inorganic salts, little protein, few cells
• fills subarachnoid space and ventricular system of brain

Question 21

What is CSF produced by?

Answer 21

produced in ventricles by the choroid plexus - specialised areas of ventricular lining

Question 22

What is the function of CSF?

Answer 22

1. buoyancy - brain and spinal cord float to reduce traction
2. cushioning effect to dampen trauma
3. transport of substances: nutrients, dissolved gases, removal of metabolites
4. provides stable environment

Question 23

What are ventricles in the brain?

Answer 23

-fluid filled cavities inside the adult brain

Question 24

what are 3 important ventricles?

Answer 24

• lateral ventricles
• third ventricle
• fourth ventricle

Question 25

What are each of the ventricles derived from in embryonic development?

Answer 25

lateral ventricle - telencephalon 3rd ventricle - diencephalon 4th ventricle - mesencephalon and myelencephalon

Question 26

What connects the lateral ventricle to the 3rd ventrcile?

Answer 26

interventricular foramina (of Monroe)

Question 27

What connects the 3rd ventricle to the 4th ventricle?

Answer 27

cerebral aquaduct

Question 28

From which part of the ventricular system does CSF escape from?

Answer 28

foramina of luschka - lateral apertures on the 4th ventricle

Question 29

the body of the lateral ventricle courses through which lobes?

Answer 29

frontal and parietal

Question 30

Which lobe is the posterior horn of the LV found in?

Answer 30

occipital

Question 31

Which lobe is the inferior horn of the LV found in?

Answer 31

temporal

Question 32

Where is the 3rd ventricle found?

Answer 32

between two thalami

Question 33

Where is the 4th ventricle found?

Answer 33

between pons (anteriorly) and cerebellum (posteriorly)

Question 34

What is the choroid plexus?

Answer 34

- collection of blood vessels and specialised cells | - filters blood from the capillaries, change ion concentration, remove protein and produces CSF

Question 35

Explain how CSF travels from the choroid plexus to the subarachnoid space?

Answer 35

1. Produced by choroid plexus in lateral ventricle 2. Flows through foramina of Monroe to 3rd ventricle 3. Travels through cerebral aqueduct to 4th ventricle 4. Flows through foramina of Luschka (lateral) and foramen of magendie (medial) to reach the subarachnoid space 5. Uses the arachnoid granulations/villi to travel back

Question 36

what are cisterns?

Answer 36

expansions of the subarachnoid space / wider areas

Question 37

which site do we use to sample CSF and why?

Answer 37

The lumbar cistern - because a needle can be inserted here with little risk of damaging CSF - as the spinal cord ends before the dural sac ends so we can access the subarachnoid space and don't puncture the spinal cord

Question 38

How does venous blood from the superficial veins reach the internal jugular vein?

Answer 38

1. Superficial vein 2. Superior sagittal sinus 3. Confluence of sinuses 4. Transverse sinuses 5. Sigmoid sinus 6. IJV

Question 39

How does CSF from the deep veins reach the internal jugular vein?

Answer 39

1. deep veins 2. internal cerebral veins 3. great vein of galen 4. straight sinus 5. confluence of sinuses 6. transverse sinus 7. sigmoid sinus 8. IJV

Question 40

What condition might occur if there is a blockage in CSF circulation?

Answer 40

hydrocephalus: | CSF will accumulate upstream of blockage in ventricular system

Question 41

What would happen if there is a blockage in the cerebral aqueduct?

Answer 41

hydrocephalus and expansion of the lateral and 3rd ventricle