Anatomy Of Visual Pathways

Question 1

What are visula pathways?

Answer 1

neuronal networks that extend from the retina to the visual cortex

Question 2

Visual pathways comprise of?

Question 3

Medical importance of the visual system?

Answer 3

• Blindness is the most devastating of all sensory deficits
• Clinical examination provides precise localization of the lesions

Question 4

3 anatomical features of the visual system?

Answer 4

1. The pathway extends from the front to the back of the head
2. The are entirely supratentorial
3. Visual information in both crossed and uncrossed paths

Question 5

2 important anatomical tasks of the central visual pathway?

Answer 5

1. Related to crossing of the midline –fibers from the nasal half of each retina cross the optic chaism
2. Maintains a retinotopic map of the image falling on the retina.
   - Since eyes face forward their visual fields overlap
   - Caused by partial decussation of the optic nerves in the optic chiasm

Question 6

Describe the optic nerve?

Question 7

4 parts of the optic nerve?

Question 8

Course of the optic nerve?

Question 9

Optic nerve relationship with the CNS?

Answer 9

• As it pierces the sclera at area cribrosa, it acquires the myelin sheath.
• Because embrologically and adult anatomically, it is a tract of the CNS,
• Optic nerve is invested in meningeal coverings : Dura, arachnoid and pia matter
• Subarachnoid space around the optic nerve communicates with others around the brain and contains CSF
  > Increase in intracranial pressure is transmitted to optic nerve: Can cause detectable swelling called Papilledema = valuable diagnostic sign

Question 10

Describe the intra orbital part of the optic nerve?

Question 11

Relations of the intra orbital part?

Question 12

Describe the intra canalicular part?

Question 13

Relations of the intra canalicular part?

Question 14

Describe the intra cranial part?

Question 15

What is the optic chiasma?

Question 16

Relations of the optic chiasma?

Question 17

Organization of the optic chiasma?

Question 18

Anatomical variation in position of normal optic chiasma?

Question 19

Describe optic tracts?

Question 20

Visual fields?

Question 21

Clinial correlates of the optic chiasma?

Answer 21

1The optic chiasma rests on the diaphragm sellae in close relation to the stalk of the pituitary gland.
Laterally, it is related to the internal carotid artery
1. A Pituitary tumor may damage the medial portion of the chiasm
2. Aneurysm on one of the internal carotid arteries may damage the lateral part of the chiasm

Question 22

Describe the optic tract?

Question 23

Fibers of the optic tract?

Question 24

What is the lateral geniculate body?

Question 25

Some optic tract fibers terminate in the?

Answer 25

Superior colliculus - for orientation to visual stimuli
Pretectal area - for pupillary light reflex
Accesssory optic nuclei for reflex eye movements
Suprachaismatic nucleus of the hypothalamus – entraining circadian rhythms

Question 26

What are opric radiations?

Question 27

Geniculo-calcarine pathway?

Question 28

What is the visual cortex?