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NEURO 375 > Visual System > Flashcards

Visual System Flashcards

1
Q

Which cranial nerves are involved in the visual system?

A
  • CN II, optic
  • CN III, oculomotor
  • CN IV, trochlear
  • CN VI, abducens
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2
Q

Which cranial nerves are responsible for somatic motor movement in the visual system?

A
  • CN III, oculomotor
  • CN IV, trochlear
  • CN VI, abducens
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3
Q

Which cranial nerve is responsible for special sensory in the visual system?

A

CN II, optic

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4
Q

Which cranial nerve is responsible for parasympathetic responses in the visual system?

A

CN III, oculomotor

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5
Q

How many extraocular muscles are there?

A

6

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6
Q

What are the extraocular muscles?

A

4 straight muscles: inferior, superior, medial, lateral rectus muscles
2 oblique muscles: superior, inferior oblique muscles

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7
Q

Which cranial nerve innervates majority of the extraocular muscles? Which muscles are theres?

A
  • CN III, oculomotor
  • superior, inferior, medial rectus mm + inferior oblique mm
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8
Q

Which extraocular muscles are not innervated by CN III? Which cranial nerves are they innervated by instead?

A
  • lateral rectus muscle; CN VI, abducens
  • superior oblique muscle; CN IV, trochlear

(hint: LR6SO4)

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9
Q

Which muscle opens and moves the eyes? Which cranial nerve is it innervated by?

A

levator palpebrae superioris, CN III (oculomotor)

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10
Q

Through which bone structure does the oculomotor nerve (CN III) leave the cranial cavity?

A

superior orbital fissure

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11
Q

Through which bone structure does CN IV, trochlear nerve leave the cranial cavity?

A

superior orbital fissure

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12
Q

Through which bone structure does CN VI, abducens nerve, leave the cranial cavity?

A

superior orbital fissure

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13
Q

Which extraocular muscles would you have to contract to move your gaze to the left?

A

right medial rectus and left lateral rectus

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14
Q

Which extraocular muscle would you have to contract to cause intorsion of the eye?

A

superior oblique mm

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15
Q

Which extraocular muscle would you have to contract to cause extorsion of the eye?

A

inferior oblique mm

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16
Q

What is the effect of a lesion to the abducens nerve to the right eye? Which way would the eye deviate towards?

A

paralysis of lateral rectum muscle on right eye –> eye will deviate to the left

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17
Q

What is the function of the cornea?

A

focus light

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18
Q

What is the function of the aqueous humour?

A

maintain pressure inside the eye

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19
Q

What is the function of the iris?

A

dilation/constriction –> control light input

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20
Q

What is the function of the ciliary muscles?

A

change the lens shape to focus light

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21
Q

Where are neural tissues found in the eye?

A

retina

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22
Q

What is the macula in the eye?

A

high concentration of photoreceptors; fovea at the center

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23
Q

What is the function of the choroid in the eye?

A
  • supplies oxygen and nutrients to outer retina
  • connective tissue between sclera and outer retina
24
Q

What the is the schlera?

A

whites of the eyes

25
Q

Where is the blind spot on the eyeball?

A

optic nerve

26
Q

Are there more rods or cones in the eye?

A

rods

27
Q

Through which bone cavity does the optic nerve (CN II) exit from the cranial cavity?

A

optic canal

28
Q

Describe the visual pathway

A

lateral geniculate nucleus –> primary visual cortex –> visual association cortex

29
Q

Which axons in the visual pathway cross the optic chiasm?

A

nasal RGC axons

30
Q

Which axons in the visual pathway stay ipsilateral?

A

temporal axons

31
Q

TRUE or FALSE: each optic nerve contains only visual information from the opposite visual field.

A

FALSE –> each optic TRACT contains only visual info from the opposite visual field

32
Q

What happens if there is lesion in your right optic nerve?

A

BLINDNESS IN RIGHT EYE b/c no visual info from the right eye is getting to the primary visual cortices

33
Q

What happens if there is lesion at the optic chiasm?

A

TUNNEL VISION b/c only receive info from temporal retina

34
Q

What happens if there is lesion in the left optic tract?

A

ONLY SEE LEFT VISUAL FIELD

35
Q

What is the meyer’s loop? In which lobe is it located?

A
  • fibers that carry info from contralateral upper quadrant visual field
  • temporal lobe
36
Q

Which visual field (left/right) projects on the left LGN? right LGN?

A
  • left visual field on right LGN
  • right visual field on left LGN
37
Q

What is anopsia? What kind of lesion causes it?

A

blindness in one eye; lesion to ipsilateral optic nerve

38
Q

What is bitemporal hemianopsia? What kind of lesion causes it?

A

blindness in temporal visual field (both eyes); lesion to optic chiasm

39
Q

What is left homonymous hemianopsia? What kind of lesion causes it?

A

left visual field impaired in both eyes; lesion to right optic tract

40
Q

What is the dorsal pathway of the visual system responsible for?

A

spatial relationships of objects

41
Q

What is the ventral pathway of the visual system responsible for?

A

object recognition

42
Q

How does damage to the temporal cortex affect the visual system? What is this condition known as?

A

poor object recognition; visual agnosia

43
Q

What are the parasympathetic responses of CN III?

A
  • pupillary light reflex
  • near (accomodation) reflex
44
Q

Describe the parasympathetic innervation pathway of CN III, oculomotor.

A

CN III –> ciliary ganglion –> short ciliary nerves –> sphincter pupillae muscle OR ciliary muscle

45
Q

What occurs during the pupillary light reflex?

A

when light is shined into one eye, both pupils constrict

46
Q

Describe the pupillary light reflex pathway, starting from when light is shined in the right eye.

A
  1. light shined in right eye
  2. AP from right eye reach both RIGHT and LEFT PRETECTAL NUCLEI
  3. pretectal nuclei stimulate BOTH SIDES of the EDDINGER-WESTPHAL nucleus
  4. both sides of eddinger-westphal nuclei generate AP through RIGHT AND LEFT CN III’s
  5. BOTH PUPILS constrict
47
Q

direct pupil dilation is __________ to light.

A

ipsilateral

48
Q

consensual pupil dilation is ___________ to light.

A

contralateral

49
Q

WHere does the optic tract synapse in the pupillary light reflex pathway?

A

pretectal area

50
Q

Where does the oculomotor nerve (CN III) synapse in the pupillary light refelx pathway?

A

ciliary ganglion

51
Q

TRUE or FALSE: the cortex is involed in the pupillary light reflex.

A

FALSE

52
Q

TRUE or FALSE: the cortex is involved in the near (accommodation) reflex

A

TRUE

53
Q

What does the near (accommodation) reflex do?

A
  • constrict ciliary muscle (accommodation)
  • pupillary constriction
  • convergence of the 2 eyes
54
Q

Which extraocular muscles are responsible for the convergence of the two eyes?

A

medial rectus

55
Q

Describe the near reflex pathway, starting from when visual info reaches the optic tract.

A
  1. optic tract (CN II)
  2. primary visual cortex
  3. visual association cortex
  4. oculomotor nucleus –> oculomotor nerve –> contract medial rectus muscle (converge 2 eyes)
  5. EW nucleus –> ciliary ganglion –> contract ciliary muscle and pupillary sphincter (accommodate lens and constrict pupil)

NEURO 375 (19 decks)

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