s3 meninges and dural folds

Question 1

what are the layers of the meninges? spaces? leptomeninges?

Answer 1

• Pia mater- microscopic layer stuck to surface of brain tissue
• Arachnoid mater - soft, fibrous, translucent membrane extends down longitudinal fissure NOT lateral fissure

Dura mater- tough fibrous membrane

> subarachnoid space between Pia and arachnoid is filled with CSF + cerebral arteries and veins
there’s a potential subdural space between dura and arachnoid matter

*= leptomeninges

(remember PAD inside out (pee is on the inside)

Question 2

gyri vs sulci

Answer 2

gyri- bumps

sulci- dips

irregular surface of brain

Question 3

layers of dura?

Answer 3

periosteal= part against inner table of bone
meningeal= part adjacent to arachnoid

Question 4

how are dural folds/sinuses created

Answer 4

separation of two layers of dura

> forms dural fold when meningeal layer extends downwards from cranial vault

> forms cavernous sinus on cranial floor

Question 5

name two dural folds and their position

Answer 5

falx cerebri>midline extends down between two hemispheres

tentorium cerebelli>lateral aspect teased in horizontal direction

*dural venous sinus formed where these two meet

Question 6

name of the opening for brainstem to pass through posterior cranial fossa

Answer 6

tentorium notch

Question 7

function of dural folds

Answer 7

help to stabilise brain and act as. rigid dividers

limitation> rise in pressure inside skull secondary to a bleed can lead to compression and displacement (herniation) of parts of brain against the rigid dural folds or through the foramen magnum

Question 8

what’s a dural venous sinus?

Answer 8

venous blood filled space created by separation of the two dural layers

• connect to each other and receive blood from cerebral veins
• exit through base of skull> drain into internal jugular vein

Question 9

what are the connections between the dural venous sinuses and other venous structures ?

Answer 9

cerebral veins via bridging veins

scalp veins via emissary veins

Question 10

weakest point of bridging veins?

Answer 10

point at which it feeds into dural venous sinus>can snap and blood fill subdural space

Question 11

clinical complication of emissary veins?

Answer 11

infection may develop in scalp due to wounds and can spread deep inside skull through these veins

Question 12

name of bleeding within brain tissue

Answer 12

intracerebral haemorrhage

Question 13

what causes extra dural haemorrhage? patient presentation?

Answer 13

arterial bleed- patient deterioration more rapid
- bleed between periosteal layer of dura and inner table

patient loses consciousness after head bump, seem normal, headache, rapid neurological function decline 1hr after (lucid interval)

Question 14

what causes subdural haemorrhage? patient presentation? likely in who?

Answer 14

venous bleed usually from bridging veins

patient initially appears normal then gradual decline as pressure rises

likely occur in elderly with only minor head injury due. to cortical shrinkage> bridging veins under higher tension due to shrinking of brain so more easily snapped.

Question 15

what causes subarachnoid haemorrhage? patient presentation?

identify via which investigations?

Answer 15

Arterial bleed
> secondary to trauma or spontaneous rupture
- usually a branch of ‘ Circle of Willis’

> blood leaks into subarachnoid space mixing with CSF
- often fatal

blood irritant to meninges so headache. and feel like been hit with a bat

identify via CT head or lumbar puncture if CT inconclusive >shows hb degradation products in CSF