Visual pathway

Question 1

What are two stages in visual pathway?

Answer 1

Extracranial
Intracranial

Question 2

Outline visual pathway?

Answer 2

Extracranial
1) Optic nerve made axons from retinal ganglion cells
2) Retinal ganglion cells recieve impulse rods and cones
3) Optic nerve leaves via optic canal through sphenoid bone
4) Enter cranial cavity
5) Run along cranial fossa

Intracranial
1) Optic nerves join at optic chiasm
2) At chiasm fibres from:
medial halves- cross to contralateral optic tract
lateral halves- ipsilateral
3) Optic tracts travel to lateral geniculate nucleus in
thalamus
4) Fibres synapse

Question 3

Answer 3

Question 4

What recieves impulses from rods and cones?

Answer 4

Optic nerve
Formed retinal ganglion cells

Question 5

Where do fibres meet?

Answer 5

Optic chiasm

Question 6

At chiasm what occurs to fibres?

Answer 6

Medial- cross to contralateral optic tract
Lateral- remain ipsilateral

Question 7

Where do fibres synapse?

Answer 7

Lateral geniculate nucleus

Question 8

Function of lateral geniculate nucleus?

Answer 8

Site where fibres synapse

Question 9

How do axons from LGN carry visual info?

Answer 9

Via optic radiation

Question 10

What is optic radiation divided into?

Answer 10

Upper optic radiation
Lower optic radiation

Question 11

Function upper optic radiation?
Where do fibres travel?

Answer 11

Carry fibres from superior quadrant (Baumans)
Fibres travel through parietal lobe to visual cortex

Question 12

Function lower optic radiation?
Where do fibres travel?

Answer 12

Carry fibres from inferior quadrants
Fibres travel through temporal lobe to visual cortex

Question 13

NB: Superior retinal quadrants correspond to inferior visual field quadrants and inferior retinal quadrants correspond to superior visual field quadrants

Answer 13

NB: Superior retinal quadrants correspond to inferior visual field quadrants and inferior retinal quadrants correspond to superior visual field quadrants

Question 14

Answer 14

Question 15

Define intortion?

Answer 15

Internal rotation
Toward midline

Question 16

Define extortion?

Answer 16

External rotation
Away midline

Question 17

State 6 ocular muscles?

Answer 17

Medial rectus- occ mot
Lateral rectus- abducens

Superior oblique- troch
Inferior oblique- occ mot

Superior rectus- occ mot
Inferior rectus- occ mot

Question 18

Label and state function?

Answer 18

Question 19

What movements muscle of eye responsible?

Answer 19

Question 20

Label

Answer 20

Question 21

Answer 21

Question 22

What is no vision in left eye caused by?

Answer 22

Damage left optic nerve

Question 23

What does damage to optic chiasm lead to\?

Answer 23

Loss vision in temporal visual fields
Hemianopia

Question 24

What does damage to left optic tract cause?

Answer 24

Loss vision temporal field left eye
Loss vision nasal field right eye

Question 25

Damage to meyers loop?

Answer 25

Loss of vision in superior nasal field of left eye
Loss of vision in superior temporal field of right eye

Question 26

Damage to left baums loop?

Answer 26

Loss of vision in inferior temporal field of right eye
Loss of vision to inferior nasal field of left eye

B- bottom

Question 27

Answer 27

1) Damage to the left optic nerve
No vision in left eye
2) Damage to optic chiasma
Loss of vision of the temporal visual fields- Hemianopia
3) Damage to left optic tract
Loss of vision of temporal field of left eye
Loss of vision of nasal field of right eye
4) Damage to left Meyer’s loop
Loss of vision in superior nasal field of left eye
Loss of vision in superior temporal field of right eye
5) Damage to left Baum’s loop
Loss of vision in inferior temporal field of right eye
Loss of vision to inferior nasal field of left eye