Anatomy Of Visual Pathways Flashcards
What are visula pathways?
neuronal networks that extend from the retina to the visual cortex
Visual pathways comprise of?
Medical importance of the visual system?
- Blindness is the most devastating of all sensory deficits
- Clinical examination provides precise localization of the lesions
3 anatomical features of the visual system?
- The pathway extends from the front to the back of the head
- The are entirely supratentorial
- Visual information in both crossed and uncrossed paths
2 important anatomical tasks of the central visual pathway?
- Related to crossing of the midline –fibers from the nasal half of each retina cross the optic chaism
- 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
Describe the optic nerve?
4 parts of the optic nerve?
Course of the optic nerve?
Optic nerve relationship with the CNS?
- 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
Describe the intra orbital part of the optic nerve?
Relations of the intra orbital part?
Describe the intra canalicular part?
Relations of the intra canalicular part?
Describe the intra cranial part?
What is the optic chiasma?
Relations of the optic chiasma?
Organization of the optic chiasma?
Anatomical variation in position of normal optic chiasma?
Describe optic tracts?
Visual fields?
Clinial correlates of the optic chiasma?
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
Describe the optic tract?
Fibers of the optic tract?
What is the lateral geniculate body?
Some optic tract fibers terminate in the?
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
What are opric radiations?
Geniculo-calcarine pathway?
What is the visual cortex?
