The Eye and the Brain

Question 1

what are the 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 are the 2 layers of the dura mater and their attachments

Answer 3

• periosteal - attached to bone

- meningeal - attached to meninges

Question 4

when do the 2 layers of the dura mater split

Answer 4

to enclose the dural venous sinuses

Question 5

what is the function of dural venous sinuses

Answer 5

drain deoxygenated blood from the brain and into the IJV

Question 6

where is the subarachnoid space located

Answer 6

between the arachnoid and pia

Question 7

what lies in the subarachnoid space

Answer 7

CSF and blood vessels

Question 8

what are arachnoid granulations

Answer 8

outpouchings of tissue the arachnoid that pass into the dural venous sinuses

Question 9

where does the pia mater adhere to

Answer 9

the brain, vessel and nerves exiting/entering

it follows all the contours

Question 10

what does the CSF surround

Answer 10

the brain and spinal cord

Question 11

at what spinal level does the spinal level end at

Answer 11

S2

Question 12

describe the communication between the ventricles and the subarachnoid space

Answer 12

the lateral ventricles meet the midline 3rd which then meets the 4th, the 4th drains into the subarachnoid space

Question 13

what does the subarachnoid space surrounds

Answer 13

the external aspect of the brain and the central canal travels down the spinal cord

Question 14

what is the superior sagittal sinus

Answer 14

structure filled with CSF that allows the CSF to drain through the arachnoid granulations into it

Question 15

where is the CSF produced

Answer 15

the choroid plexus

Question 16

where is the choroid plexus situated

Answer 16

in the lateral and 3rd ventricles

Question 17

what structure allows the CSF to drain from the 3rd to 4th ventricle

Answer 17

cerebral aqueduct

Question 18

where does the CSF end up

Answer 18

majority in subarachnoid space

central canal

Question 19

where is the CSF reabsorbed into

Answer 19

the dural venous sinuses

Question 20

how does increased intracranial pressure occur

Answer 20

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

Question 21

what are fontanelles

Answer 21

soft spots in young toddles

Question 22

how is intracranial pressure usually kept constant

Answer 22

the blood, brain and CSF

Monro-Kelle hypothesis

Question 23

what is the monro-kelle hypothesis

Answer 23

the blood, brain and CSF exist in equilibrium

Question 24

what problems can increased intracranial pressure cause

Answer 24

• damage to tissues
• shifts in tissues
• herniation
• constriction of blood vessels
• visual problems

Question 25

how do the meninges relate to the eye

Answer 25

they surround the nerves and extend all the way to the back of the eyeball

Question 26

how may raised ICP affect the eye

Answer 26

the pressure can transmit along the subarachnoid space in the optic nerve sheath

Question 27

what structures does raised ICP compress in the optic sheath

Answer 27

nerve, artery and vein

Question 28

what may occur as a result of ICP (not visual symptoms)

Answer 28

papilloedema

Question 29

what visual symptoms can occur as a result of raised ICP

Answer 29

- transient visual obscuration - transient flickering - blurring of vision - constriction of the visual field - decreased colour perception

Question 30

how are dural septae formed

Answer 30

by the fold of the meningeal dira

Question 31

what dural septae divide the cranial cavity and help support the brain

Answer 31

falx cerebri and tentorium cerebelli

Question 32

what dural septae divides the two cerebral hemispheres

Answer 32

falx cerebri

Question 33

what dural septae blends into the tentorium cerebelli

Answer 33

falx cerebri

Question 34

what does the tentorium cerebelli divide

Answer 34

the infra- and supra-tentorial compartments

Question 35

what is the tentorium notch and what passes through it

Answer 35

- gap in the free anteromedial edge of the tentorium | - brainstem

Question 36

how might raised ICP effect the oculomotor nerve

Answer 36

medial temporal lobe may herniate through the tentorial notch compressing/stretching the nerve

Question 37

what fibres of CN III are affected first in nerve compression/stretch

Answer 37

parasympathetic

Question 38

what is the first sign of CN III damage

Answer 38

ipsilateral pupil dilation

Question 39

what does CN III damage result in

Answer 39

paralysis of somatic motor innervation (4 extra-ocular muscles and eyelid) and paralysis of parasympathetic innervation of the sphincter of the pupils

Question 40

what clinical symptoms occur with CN III damage

Answer 40

- slow/no pupillary light reflex - dilated pupil - ptosis - down and out gaze

Question 41

what occurs with CN IV damage

Answer 41

- paralysis of the superior oblique - eyes move inferolaterally - diplopia

Question 42

what occurs with CN VI damage

Answer 42

eye cant move laterally and deviated medially