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Neuroanatomy > Visual > Flashcards

Flashcards in Visual Deck (36)
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1
Q

What are the 3 cellular layers of the retina, in order that light goes through first.

A
  • Ganglion cell layer
  • Bipolar cell/interneuron layer
  • Photoreceptors
2
Q

Axons of what cells form the optic n.?

A

Ganglion cells (first AP)

3
Q

Rods vs. cones-

Which has more photopigment per cell?

A

Rods (larger/taller)

4
Q

Rods vs. cones-

Which has higher temporal resolution/faster response/shorter integration time?

A

Cones (less convergence in pw)

5
Q

Rods vs. cones-

Which are saturated in daylight?

A

Rods

6
Q

Rods vs. cones-

Which has more convergence on retinal pw’s?

A

Rods

7
Q

Where in the retina is our best visual acuity?

A

Fovea (cones only)

8
Q

Explain the entire visual pw from photoreceptor to cortex.

A
  1. Photoreceptor stimulates ganglion cell to send first AP.
  2. AP reaches optic n.
  3. Nasal portion of retinal nn. cross at optic chiasm, temporal portions do not. Optic tract is formed.
  4. Optic tract synapses at LGN of thalamus
  5. Optic radiations reach visual cortex
9
Q

Rods vs. cones-

M-type ganglion cells are associated w/_____, P-type cells are associated w/_____.

A

Mr. PC

  • Rods (respond best to Movement)
  • Cones (respond best to color and fine details)
10
Q

What is the Brodmann’s area # for the primary visual cortex?

What’s another name for it?

A
#17
- Striate cortex
11
Q

Where are visual reflexes processed in the brainstem (not the cortex)?

A

*Pretectal area

12
Q

Where are head and eye movements processed in the brainstem (not the cortex)?
[E.g. orienting reflex when something wiggles in our peripheral vision.]

A

*Superior colliculus

13
Q

Regarding optic radiations, upper fibers run thru the _______________, lower fibers run thru the _______________.

A
  • Parietal lobe

- Temporal lobe

14
Q

How do lower fibers (of optic radiations) reach their path in the cortex?

A

Meyer’s loop

15
Q

What physical/anatomical landmark runs deep to divide the occipital lobe at Brodmann’s area #17?

A

Calcarine fissure

16
Q

What is the result of cutting the right optic n.?

A

Right eye blindness

17
Q

Cutting the center of the optic chiasm only would lead to what?

A

Bitemporal hemianopia–loss of R field of R eye and L field of L eye
(besides cutting optic n., this is only result that effects both eyes differently)

18
Q

What is the result of cutting the right optic tract or lesioning the right LGN?

A

Left homonymous hemianopia–loss of left field of both eyes

19
Q

Right temporal lobe lesion would lead to what result?

A

“Pie in the sky” Left homonymous upper quadrantanopia–loss of pie slice on upper left of both eyes

20
Q

Cutting of the right optic radiation would lead to what result?

A

Left homonymous lower quadrantanopia and macular sparing is often present–loss of most of left field of both eyes, sometimes center is spared

21
Q

Lesion of the right visual cortex would lead to what result?

A

Left homonymous hemianopia with macular (fovea) sparing–loss of entire left field of both eyes w/center spared

22
Q

After a deceleration injury, what is a common visual effect?

A

Loss of center of field only

23
Q

What’s the name of the test that tests the optic n.?
What are the names of the 2 subtype reflexes?
What are we testing to confirm functionality?

A
  • Pupillary light reflex
  • If you shine a light in 1 eye, the response of the illuminated eye is the direct reflex, the response of the unilluminated eye is the consensual response.
  • Testing both eyes confirms rostral midbrain is functional
24
Q

What is the nucleus associated with the pupillary light reflex?
How come the reflex effects both eyes?

A
  • Edinger-Westphal nucleus (EWN)

- Single optic n. splits at chiasm to supply both EWN’s.

25
Q

After leaving the EWN, what efferent CN goes on to perform the pupillary light reflex?
What nucleus does this CN synapse at before reaching the eye, and what major (brainstem) area does this CN travel thru before reaching said nucleus?

A
  • CN III
  • Ciliary ganglion (bilaterally)
  • Sup colliculus
26
Q

After R optic n. dmg, describe the pupil size of each.

How would each pupil respond to light when light is shown in each eye?

A
  • Both have normal pupil size

- Neither responds to light shown into R eye. Both constrict w/light to L eye.

27
Q

After R oculomotor n. dmg, describe the relative pupil size of each eye.
How would each pupil respond to light?

A
  • R pupil is dilated, L is normal

- R eye doesn’t respond to light shown in either eye (L eye should respond to light shown in either eye)

28
Q

What causes Horner’s syndrome and what are the sx, + is it contralateral or ipsilateral?

A
  • Loss of sympathetic output to the head
  • Ptosis (of eyelid), miosis (constricted pupil), anhydrosis (loss of sweating)
  • Ipsilateral to lesion
29
Q

If someone had a lesion to CN III, what direction would their eye appear to be looking?

A

Down and out

30
Q

What is the purpose of the accommodation reflex?

What eye movements does it entail?

A

Changing gaze to focus on nearby object.
- Vergence of eyes, ciliary m. constriction (lens thickens), constriction of both pupils
(conscious act, so involves cerebral cortex)

31
Q

What initiates the corneal eye blink reflex?

What is the pathway? (think hard)

A
  • Free nerve endings in the cornea (among anything else that might make you blink)
  • Cornea > CN V > Chief sensory nuc of V > interneurons (reticular formation) > Motor nuc of VII > CN VII > obicularis oculi (blinks)
32
Q

What is the greatest numerical layer in the visual cortex and what does it do?

A

Layer IV, processes input (there’s lots of input)

33
Q

What are the 3 main specialized “hypercolumns” of the visual cortex?

A
  1. Orientation (edges)
  2. Blobs (color)
  3. Ocular dominance (L vs. R)
34
Q

“Where” an object is is determined in the _______________, “what” an object is is determined in the _______________.

A
  • Parietal lobe

- Temporal lobe

35
Q

What are the 2 basic ways to detect motion of an object?

A
  1. Temporal association: image moves temporally across retina while eye remains stationary
  2. Head and eyes move to fix image on the fovea
    - Both indicate that the object must be moving
36
Q

What colors are part of the eye’s cone system?

How many different photoreceptor types do we need to perceive color?

A
  • Red, green, blue (wavelength ranges overlap)

- 2