Chapter 19 Opticals

Question 1

Fibrous Tunic

Answer 1

• sclera (white)

- cornea (transparent)

Question 2

Vascular Tunic

Answer 2

• choroid
• ciliary body
• iris

Question 3

Neural Tunic

Answer 3

retina

Question 4

What keeps muscles in the eye in place?

Answer 4

lots of fat

Question 5

Three tunics form the ‘globe’ of the eye:

Answer 5

fibrous, vascular, neural

Question 6

Sclera

Answer 6

• attachment site for extrinsic eye muscles

- elastic/mechanical support

Question 7

What does the cornea bulge do?

Answer 7

refracts light before it hits lens

Question 8

Choroid

Answer 8

-vascular = helps nourish retina
-black pigmentation absorbs “stray” light
(waffe-like in lab)

Question 9

Ciliary body

Answer 9

• muscle & ligaments
• smooth muscle (radial and sphincter-like fibers)
• suspensory “ligament” of the lens

Question 10

Iris

Answer 10

• color of eye
• smooth muscles (radial and sphincter-like) fibers
• muscle contraction = diameter of pupil

Question 11

What fills the anterior cavity?

Answer 11

aqueous humor

Question 12

aqueous humor

Answer 12

• produced by the ciliary process
• returned to blood supply via the Canal of Schlemm
• helps control intra-ocular pressure

Question 13

What fills the posterior cavity?

Answer 13

vitreous humor (gel-like)

Question 14

vitreous humor

Answer 14

helps maintain shape of eyeball

Question 15

Suspensory ligament

Answer 15

• barrier btw ant/post cavities

- lens is suspended btw layers

Question 16

Glaucoma

Answer 16

• circulation of aqueous humor is blocked (disease of anterior cavity)
• increased pressure > damage to optic nerve
• edema of the cornea > cloudy/grey-green eye
• associated w/ high blood pressure

Question 17

Posterior pigmented layer of the retina

Answer 17

-dark pigmentation absorbs stray light

Question 18

Anterior ‘neural layer’

Answer 18

• contains 9 layers

- ganglia = integration & preliminary processing

Question 19

Rods

Answer 19

• light & dark

- cheap to operate

Question 20

Cones

Answer 20

• color
• absence =color blindness
• expensive to operate

Question 21

Macula lutea & the Fovea centralis

Answer 21

• center of visual axis
• contains high conc. of cones
• sharpest focus

Question 22

Blind spot (optic disk)

Answer 22

• point where optic nerve exits the globe
• point where blood vessels enter/exit the globe
• located very close to and medial of the fovea

Question 23

Globe of the eye and the retina

Answer 23

• formed as lateral diverticula of the diencephalon

- appears to be installed backwards

Question 24

Mechanical limitations

Answer 24

• rod & cones point the wrong way
• receptors buried behind 9 layers
• blind-spot where axons & blood vessels leave globe

Question 25

Result of mechanical limitations

Answer 25

70% of the image is lost (only 30% efficient)

Question 26

Pineal gland

Answer 26

- tied to light reception: diurnal behavior patterns - tied to sleeping & melatonin - seat of the soul

Question 27

Why do eyes turn red w/ flash?

Answer 27

bc of so many blood vessels in the back of the eye

Question 28

Gray matter

Answer 28

rods/cones - deep layer

Question 29

White matter

Answer 29

vasc/ganglia - superficial layer

Question 30

Iris (CN III):

Answer 30

- antagonist muscles - sympathetic stimulation > dilation of pupil - parasympathetic stimulation > contraction of pupil

Question 31

Ciliary muscle (CN III)

Answer 31

- contraction affects how lens is stretched | - shape of lens affects where eye focuses

Question 32

Do ciliary muscles pull on suspensory ligaments?

Answer 32

NOO

Question 33

Lens

Answer 33

- suspended from sclera by suspensory ligament | - no BV's present

Question 34

Photic sneeze reflex

Answer 34

-parasym. tries to close eye to limit light connected w/ nose so believes something in nose

Question 35

Accommodation

Answer 35

- ability to focus | - requires change in lens shape

Question 36

Close objects

Answer 36

- parasympathetic | - ciliary muscles contract, ligaments sag, & lens bulges

Question 37

Far objects

Answer 37

- sympathetic | - ciliary muscles relax, ligaments tighten, & lens thins

Question 38

Can the lens move?

Answer 38

no, only change shape

Question 39

Presbyopia

Answer 39

- lens proteins become "stiffer" with old age | - can't focus on near objects = far-sighted

Question 40

Cataracts

Answer 40

- lens becomes cloudy | - focusing becomes "patchy" across retina

Question 41

Astigmatism

Answer 41

- refractive errors of the cornea | - glases/lenses help w/ correction

Question 42

Levator palpebrae superioris

Answer 42

lifts upper eyelid (CN III)

Question 43

Orbicularis oculi

Answer 43

closes both eyelids (CN VII)

Question 44

Palpebrae

Answer 44

upper & lower eyelids

Question 45

Caruncle

Answer 45

lacrimal

Question 46

Canthi

Answer 46

medial near caruncle & lateral canthus | -corner

Question 47

Conjunctiva

Answer 47

- skin over anterior surface of eye | - pink-eye

Question 48

Lacrimal gland

Answer 48

- superolateral corner of orbit | - wash, moisten, minimize friction

Question 49

Lacrimal apparatus

Answer 49

-tears are squeezed into medial canthus with each blink

Question 50

How tears drain?

Answer 50

lacrimal puncta > lacrimal canaliculi > lacrimal sac > nasolacrimal duct > nasal cavity

Question 51

Trochlea

Answer 51

sling of CT for superior oblique muscle