Visual pathways

visual field defects grays-8th.png

  1. monocular scotoma
  2. optic nerve: monocular blindness
  3. optic chiasm: bitemporal hemianopia
  4. optic tract: contralateral homonymous hemianopia
  5. optic radiation in temporal lobe: contralateral homonymous superior quadrantanopia
  6. contralateral homonymous hemianopia with macular sparing
  7. ditto
  8. bilateral central scotoma

this macular sparing business seems too good to be true

  • classically considered to be a clinical sign of posterior cerebral artery thrombus
    borrowing liberally from Horton et al 2021,
  • first classical theory suggested dual representation of occipital pole, i.e. bilaterally
  • second theory is that occipital pole has collateral circulation from MCA
    • perfusion of occipital lobe is very variable
    • macular representation is magnified
  • "Some topics become so mired in confusion that it becomes nearly impossible to extricate them" - this is promising

pathology

Argyll-Robertson pupil

  • not responsive to light
  • responsive to accommodation
  • constricted
  • textbook sign of neurosyphilis
  • ?bilat damage to pretectal nuclei in midbrain

#anatomy-eye #innervations #neuroanatomy

https://teachmeanatomy.info/head/cranial-nerves/optic-cnii/
Horton et al 2021 https://pmc.ncbi.nlm.nih.gov/articles/PMC8638601/ - Leff 2004

Optic nerve
Orbit
Horner's syndrome