Visual Pathways

Question 1

The intra ocular portion of the optic nerve is how long?

Answer 1

1 mm in length

Question 2

What is the arterial supply to the intra ocular portion of the optic nerve?

Answer 2

Shorts, posterior ciliary artery, and circle zinn

Question 3

At the lamina cribosa , ganglion cells are myelinated by…

Answer 3

Oligodendrocytes

Question 4

What is the maculopapular bundle

Answer 4

Ganglion cells of the macular and via the macular papular bundle which enters the optic disc at centre.

Question 5

How long is the intraorbital section of the optic nerve?

Answer 5

24mm (longest)

Question 6

What is the blood supply to the intraorbital section of the optic nerve?

Answer 6

plial vessels and Central collateral artery

Question 7

What is the blood supply to the intracranial section of the optic nerve?

Answer 7

blood supply: pial plexus, superior hypophyseal and internal carotid branches

Question 8

What is the path of the intracranial portion of the optic nerves ?

Answer 8

 Passes superiorly medially posteriorly to optic chiasm which is at the floor of the third ventricle

• reaches optic chiasma and the floor of the 3rd ventricle
• above the intracranial portion of optic nerve –> lies the olfactory nerve (C 1)

Question 9

Superior to optic chiasm is…

Answer 9

Question 10

Optic chiasm relations

Answer 10

Question 11

infero-nasal retinal nerve fibres cross chaisma…

Answer 11

> infero-nasal retinal nerve fibres cross
chaisma anteriorly, travel to the contralateral optic nerve before
travelling in the contralateral optic tract
This is known as knee of Von willebrand..

Therefore, lesion on the anterior right aspect of chiasm causes junctional scotoma, ie defect in superior left quadrant

Question 12

> supero-nasal retinal nerve fibres cross chiasma…

Answer 12

> supero-nasal retinal nerve fibres cross chiasma posteriorly and travel through the the contralateral optic tract

Question 13

Arterial supply to optic tract?

Answer 13

: branches of anterior choroidal, middle cerebral and posterior communicating arteries

Question 14

The optic tract rotates by how many degrees

Answer 14

90° while winding round the brain stem

Question 15

Where is the Lateral gen nucleus located

Answer 15

Pulvinar Thalamus

Question 16

How many laminated layers does the IGN have

Answer 16

S ix

Question 17

Optic radiations from Lgn are called

Answer 17

Myers’s loop

Question 18

Optic radiations from mgn are called

Answer 18

Baum’s loop

Question 19

Nasal retinal, fibres terminates, in which part of the LGn

Answer 19

1 4 6

Question 20

Temporal retinal fibres terminate in which area of the LGN

Answer 20

235

Question 21

LGN blood supply

Answer 21

blood supply anterior choroidal artery and thalamogeniculate

Question 22

Blood supply to optic radiation

Answer 22

blood supply: anterior radiations supplied by anterior choroidal artery;

posterior Radiations supplied by posterior (mainly) & middle cerebral arteries and lateral striate a.

Question 23

Optic chasm blood supply

Answer 23

chiasma blood supply: pial plexus supplied by mainly internal carotid arteries, plus superior hypophysial branches, posterior and anterior communicating a. supply

Question 24

What is meyers loop

Answer 24

> lateral portion of LGN gives rise to Meyer’s loop optic radiations
Meyer’s loop fans laterally within the temporal lobe before swinging posteriorly toward the inferior wall of the calcarine sulcus visual cortex (pg. 93)

Remember PITS

Question 25

What is Baum loop

Answer 25

Arises from MEDIAL PORTION of LGN which recieves impulses from superior retinal ganglion fibres ie. inferior visual field medial portion of LGN gives rise to Baum's loop optic radiations Baum's loop fans immediately superiorly and posteriorly within the parietal lobe heading direcIty toward the superior wall of the calcarine sulcus visual cortex Remember PITS

Question 26

What are magnocellular cells

Answer 26

Part of the LGN IN LAYERS 1 and 2 Connected to parasol ganglion cells Responsible for: Motion detection Depth perception Low acuity/resolution High contrast sensitivity (monochromatic)

Question 27

Magnocellular cells receive input from

Answer 27

Parasol ganglion cells

Question 28

Parasol ganglia cell function

Answer 28

Question 29

What are parvocellular cells

Answer 29

Part IGN in layer 3-6

Question 30

parvocellular cells receive input from..

Answer 30

Midget ganglion cells

Question 31

Midget ganglion cells are responsible for

Answer 31

Question 32

Kiniocellular cells in Lgn receive input from

Answer 32

Bistratified ganglion cells which are connected to rods and cones

Question 33

Brodmann's area 17 is the

Answer 33

Primary visual cortex

Question 34

Most optic radiations terminate in which area of the primary visual cortex

Answer 34

Layer 4 (some in 6)

Question 35

Play five of the primary visual cortex is connected to…

Answer 35

Superior collículos to inform eye movement

Question 36

The right visual field is controlled by which area in the primary cortex

Answer 36

The left ( all inverted, ie superior field, controlled by inferior aspects of cortex)

Question 37

The secondary visual areas are known as…

Answer 37

Brodmann area 18 & 19, aka extra striate cortex

Question 38

What are the blood vessels to the visual parts of the brain?

Answer 38

Blood supply to brain tissue concerned with vision > middle cerebral artery supplies the frontal eye field < > posterior (mainly) & middle cerebral arteries supply the visual cortex < > calcarine artery (branch of posterior cerebral) supplies the visual cortex <

Question 39

pathology in the FEF leads…

Answer 39

to a conjugate gaze deviation toward the side of the damage (ipsilateral gaze defect)

Question 40

PARAMEDIAN PONTINE RETICULAR FORMATION (PPFR) lesion causes…

Answer 40

cause loss of horizontal saccades toward the side of the lesion and/or horizontal gaze deviation which are evident clinically

Question 41

What is the path of the intracanalicular aspect of ophthalmic nerve

Answer 41

- optic canal lies within the lesser wing of the sphenoid bone - meninges continue through the optic canal - dura fuses with periorbita which fixes nerve - ophthalmic artery passes inferolaterally to optic nerve in the optic canal

Question 42

What is the blood supply to the intracanalicular aspect of optic nerve.

Answer 42

Plial plexus and branches of ophthalmic artery