Lecture 11 (EYEBALLS) Flashcards
Exterior eye anatomy
- sclera
- margins of cornea
- iris
- pupil
Basic inner anatomy
- cornea
- lens
- cilliary muscle
- vitreous humor
- macula
- optic nerve (CN2)
- retina
- choroid
back of the eye anatomy
- nervous layer of retina
- optic disc (blind spot)
- optic nerve
- central veins and arteries
tunics of the eye
- fibrous tunic (sclera + cornea)
- vascular tunic (choroid, ciliary body and iris)
- retina (pigmented and nervous layer)
photoreceptors
rods (black and white) and cones (RGB)
receives info for optic nerve
retinal ganglion cells (RGB)
Macula
little crater in the retina, surrounds the fovea
Fovea
central fixation point of the eye, highest visual aquity
Hyperopia vs Myopia
focal point is too far from retina (farsighted), focal point is too close (nearsighted)
Lens cataract
cloudy lens refracts light, blurry vision
cranial nerves involved in vision
CN 2-7
Sensory:
- 2 optic (relay visual input from RGC)
- 5 trigeminal (sensation)
Motor:
- 3 oculomotor (open eyes, 4/6 eye muscles, miosis)
- 4 trochlear (superior oblique)
- 6 abducens (lateral rectus)
- 7 facial (lacriminal secretions (tears), close eyes, ciliary muscle)
Optic neural pathway
Ex: right visual field
- inner R eye, outer L eye
- crosses at optic chiasm
- L optic tract
- L lateral geniculate nucleus
- L optic radiations
- L primary visual cortex
Visual field defects
eg: lesion on left side
1: Monocular blindness - L optic nerve - L eye blind
2: Bitemporal hemianopia - medial branches of optic chiasm - lateral blindness in both
3: Right Homonymous hemianopia - L optic tract - loss of R half of visual field
4: Right superior homonymous quadrantanopia - L lateral GN - loss of R upper quadrants
5: Right inferior homonymous quadrantanopia - L optic radiations - loss of R lower quadrants
Glaucoma
- high pressure in eye caused by lack of drainage of aqueous humor in anterior chamber
- can compress optic nerve (optic nerve cupping) kills RGC
eyelid muscles and nerves
levator palpebrae - 3 (oculomotor) - OPEN
orbicularis oculi - 7 (facial) - CLOSE
extraocular eye muscles and nerves
Rectus:
lateral - 6 (abducens) - look out
medial - 3 (oculomotor) - look in
superior - 3 - look up
inferior - 3 - look down
Obliques:
superior - 4 (trochlear) - turn out and down
inferior - 3 - turn in and up
(superior to back of eye from top of eye like a pulley, inferior to lateral side of eye from medial skull)
Damage to nerves
damage to a nerve will reduce muscle tone
- oculomotor palsy (CN3, exotropia and ptosis)
- abducens palsy (CN6, esotropia)
- trochlear palsy (CN4,
- mydriasis (CN3 or parasympathetic NS,)
- miosis + ptosis (sympathetic NS)
eye deviations
ptosis: eyelid closed (should be open)
exotropia: look down and out (should be middle)
esotropia: look middle (should be lateral)
miosis: pupil constricted
mydriasis: pupil dilated
