The Eye and Raised ICP

Question 1

what are meninges?

Answer 1

protective coverings of the brain and spinal cord

Question 2

what are the three layers of the meninges?

Answer 2

dura mater
arachnoid mater
pia mater

Question 3

what provides the sensory nerve supply to the dua mater?

Answer 3

CN V

Question 4

what is enclosed in the dura mater?

Answer 4

the dural venous sinuses

Question 5

what are the two layers the dura mater splits into around venous sinuses?

Answer 5

periosteal layer (outer)
meningeal layer (inner)

Question 6

what does the pia mater adhere to?

Answer 6

the brain and any vessels entering/leaving

Question 7

what is found between the arachnoid mater and the pia mater?

Answer 7

the subarachnoid space

Question 8

what is found in the subarachnoid space?

Answer 8

CSF

blood vessels

Question 9

how can the subarachnoid space be accessed clinically and why would this be done?

Answer 9

lumbar puncture

to get a CSF sample

Question 10

where is a lumbar puncture done?

Answer 10

L3/4 or L4/5 levels

Question 11

when does the subarachnoid space end?

Answer 11

vertebral level S2

Question 12

what are the four ventricles of the brain?

Answer 12

lateral x 2 (left and right)
third ventricle
fourth ventricle

Question 13

what secretes CSF?

Answer 13

the choroid plexus in the lateral and third ventricles

Question 14

what connects the third and fourth ventricles?

Answer 14

the cerebral aqueduct

Question 15

how is CSF reabsorbed and where?

Answer 15

via arachnoid granulations

into the dural venous sinuses

Question 16

what is raised ICP?

Answer 16

increased pressure in the cranial cavity

Question 17

what causes raised ICP?

Answer 17

increased pressure either in the CSF or within the brain itself

Question 18

why is raised ICP a serious emergency?

Answer 18

can damage the brain and spinal cord by compressing them

Question 19

what is a common symptom experienced by patients with raised ICP?

Answer 19

visual problems

Question 20

what is CN II?

Answer 20

the optic nerve

Question 21

what covers CN II?

Answer 21

meninges

Question 22

what does the optic nerve being surrounded by meninges mean?

Answer 22

increased ICP will be transmitted around the optic nerve = results in papilloedema

Question 23

what is papilloedema?

Answer 23

swollen optic discs

Question 24

what are dural septae?

Answer 24

folds of dural matter that create septae in the cranial cavity

Question 25

what are the four dural septae?

Answer 25

falx cerebri
tentorium cerebelli
falx cerebelli
diaphragma sellae

Question 26

what is the largest dural septa?

Answer 26

falx cerebri

Question 27

what does falx cerebri divide?

Answer 27

the two cerebral hemispheres

Question 28

what does the tentorium cerebelli divide?

Answer 28

the cranial cavity into supratentorial and infratentorial areas

Question 29

what does the falx cerebelli divide?

Answer 29

the cerebellum into the right and left halves

Question 30

what does the diaphragma sellae cover?

Answer 30

the roof of the pituitary fossa

Question 31

what is CN III?

Answer 31

the oculo motor nerve

Question 32

how can raised ICP compress CN III?

Answer 32

if the medial temporal lobe herniates through the tentorial notch

Question 33

what is the tentorial notch?

Answer 33

the free edge of the tentorium cerebelli where the brainstem exits

Question 34

how does CN III compression present?

Answer 34

absent pupillary light reflex
dilated pupil
ptosis
eye turned inferolaterally (out and down)

Question 35

what is CN IV?

Answer 35

the trochlear nerve

Question 36

what does damage to CN IV cause?

Answer 36

paralysis of the superior oblique muscle