Lecture 11 (EYEBALLS)

Question 1

Exterior eye anatomy

Answer 1

• sclera
• margins of cornea
• iris
• pupil

Question 2

Basic inner anatomy

Answer 2

• cornea
• lens
• cilliary muscle
• vitreous humor
• macula
• optic nerve (CN2)
• retina
• choroid

Question 3

back of the eye anatomy

Answer 3

• nervous layer of retina
• optic disc (blind spot)
• optic nerve
• central veins and arteries

Question 4

tunics of the eye

Answer 4

• fibrous tunic (sclera + cornea)
• vascular tunic (choroid, ciliary body and iris)
• retina (pigmented and nervous layer)

Question 5

photoreceptors

Answer 5

rods (black and white) and cones (RGB)

Question 6

receives info for optic nerve

Answer 6

retinal ganglion cells (RGB)

Question 7

Macula

Answer 7

little crater in the retina, surrounds the fovea

Question 8

Fovea

Answer 8

central fixation point of the eye, highest visual aquity

Question 9

Hyperopia vs Myopia

Answer 9

focal point is too far from retina (farsighted), focal point is too close (nearsighted)

Question 10

Lens cataract

Answer 10

cloudy lens refracts light, blurry vision

Question 11

cranial nerves involved in vision

Answer 11

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)

Question 12

Optic neural pathway

Answer 12

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

Question 13

Visual field defects

Answer 13

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

Question 14

Glaucoma

Answer 14

• high pressure in eye caused by lack of drainage of aqueous humor in anterior chamber
• can compress optic nerve (optic nerve cupping) kills RGC

Question 15

eyelid muscles and nerves

Answer 15

levator palpebrae - 3 (oculomotor) - OPEN
orbicularis oculi - 7 (facial) - CLOSE

Question 16

extraocular eye muscles and nerves

Answer 16

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)

Question 17

Damage to nerves

Answer 17

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)

Question 18

eye deviations

Answer 18

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