Meninges, Dural Folds and Dural Venous Sinuses

Question 1

What are the 3 membranous layers that surround the brain?

Answer 1

Dura = tough fibrous membrane, firmly adhered to skull (outermost)

Arachnoid = soft translucent (middle)

Pia = thin, adherent to brain surface (innermost)

Question 2

Name the potential spaces between the meninges and where they lie

Answer 2

Subarachnoid = space between arachnoid and pia

Subdural = space between dura and arachnoid

Question 3

What is between the layers of the meninges?

Answer 3

Potential space

Can fill

Question 4

What lies between the dura and inner table of bone?

Answer 4

Meningeal arteries = supply dura and bones of the skull

Question 5

What are the layers of the dura?

Answer 5

Periosteal = endosteum lining inner table of skull (outer)

Meningeal = layer adjacent to arachnoid (inner)

Question 6

What are dural folds?

Answer 6

Separations of the two layers of the dura

Meningeal layers pulling away from the periosteal layer = stuck together = fold

Question 7

What are dural venous sinuses?

Answer 7

Space created at the top of a dural fold = becomes venous channels

Cranial floor = separation of the 2 layers of dura allowing for channels

Question 8

Where do major dural venous sinuses lie?

Answer 8

Margins of borders of falx cerebri and tentorium cerebelli

Question 9

Where is the CSF located?

Answer 9

Within the subarachnoid space (cerebral blood vessels also here)

Question 10

Name the 2 important dural folds

Answer 10

Falx cerebri = between the 2 hemispheres

Tentorium cerebelli = tent sitting above cerebellum, covering posterior cranial fossa

Question 11

What is the function of the dural folds?

Answer 11

Stabilise the brain

Rigid dividers

However when vol is added = brain compression = herniation = neurological symptoms/signs

Question 12

How can you tear the dura?

Answer 12

Via crista galli bone (attachment of falx cerebri)

Potentially take the arachnoid layer with it = leaking of CSF through the nose

Question 13

Where do cerebral veins that drain the brain drain into?

Answer 13

Dural venous sinuses – IJV

Question 14

Name the venous sinuses

Answer 14

Question 15

Where are the cerebral veins found?

Answer 15

Subarachnoid space

Question 16

What layer is the dural venous sinus found?

Answer 16

Dural layer

Question 17

What are bridging veins

Answer 17

Allow cerebral veins to traverse subdural space to drain into the dural venous sinus

Connect subarachnoid space to dural sinus

Question 18

Bleeding can occur between which layers of the meninges?

Answer 18

All potential spaces

Extradural

Subdural

Subarachnoid

Question 19

What is an intracerebral haemorrhage?

Answer 19

Bleeding within the brain tissue itself

Question 20

What is a subarachnoid haemorrhage?

Answer 20

Usually ruptured branch of circle of willis = arterial circuit

Mixing with CSF

Hard to identify on CT after 24h = so sample CSF for presence of blood

Question 21

Outline the radiographic appearance of extra and sub-dural haemorrhages

Answer 21

Extra = between bone and periosteal dura, lens shape, cant pass suture lines

Sub = bleed from bridging vein (risk increases with age), banana shape, can spread 1 half of skull

Question 22

What permits entry of infections into the cranial cavity and brain?

Answer 22

Connection between the dural venous sinuses and extra-cranial veins of the scalp, orbit and face