meninges and raised ICP

Question 1

describe the dura mater

Answer 1

protective covering on the brain
“Hard mother”
Sensory supply from CN V
- Encloses dural venous sinuses

Question 2

describe the arachnoid mater

Answer 2

looks spider like, has arachnoid granulations projecting upwards

Question 3

what is the purpose of the meninges?

Answer 3

protective coverings of the brain and spinal cord

Question 4

what does the pia mate adhere to?

Answer 4

the brain

Question 5

what is found within the subarachnoid space?

Answer 5

circulating CSF and blood vessels

Question 6

where does the subarachnoid space end?

Answer 6

inferiorly at S2

Question 7

what are the 2 causes of raised ICP?

Answer 7

increased pressure in the fluid surrounding the brain or increase in pressure within the brain itself

Question 8

what is the order of the meninges from superficial to deep?

Answer 8

dura
arachnoid
pia

Question 9

what does raised ICP do to the eyes?

Answer 9

compresses optic nerve which can lead to papilloedema (bulging / swelling of optic discs)

Question 10

what kind of visual symptoms can occur in papilloedema?

Answer 10

transient visual obscurations (graying-out of vision)
transient flickering
blurring of vision
constriction of the visual field
decreased colour perception

Question 11

describe the dural septae

Answer 11

Folds of dura mater

Create septa in cranial cavity

Divide cranial cavity
- Falx cerebri
- Tentorium cerebelli

• Falx cerebelli
• Diaphragma sellae

Brain can herniate through openings

Question 12

what can happen to the oculomotor nerve in raised ICP?

Answer 12

can be compressed / stretch if medial temporal lobe herniated through tentorial notch

Question 13

what would happen is the oculomotor nerve was compressed?

Answer 13

Paralysis of somatic motor innervation
4 extra-ocular muscles and eyelid

Paralysis of parasympathetic innervation sphincter of pupil

lose/slowness of pupillary light reflex, dilated pupil, ptosis, eye turned inferolaterally
‘Down and Out’

Question 14

what happens when the trochlear nerve is compressed / stretched?

Answer 14

long course so susceptible to damage

Paralysis of superior oblique muscle - only extraocular muscle supplied by CN IV

Inferior oblique is now unopposed
eye cannot move inferomedially

diplopia when looking down

Question 15

what happens when abducens nerve is compressed or stretched?

Answer 15

Paralysis of lateral rectus muscle - only extraocular muscle it supplies

Eye cannot move laterally in horizontal plane

Medial deviation of the eye