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Undeleted > Visual Pathways/Oculomotor > Flashcards

Visual Pathways/Oculomotor Flashcards

0
Q

Cone or rod?

Function optimally in light adaptations

A

Cone

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1
Q

Cone or rod?

Mediate central and color vision

A

Cone

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2
Q

Cone or rod?

Greatest density in fovea

A

Cone

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3
Q

Greatest density of rods?

A

20 degrees from fovea

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4
Q

Cone or rods?

More abundant in peripheral retina

A

Rods

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5
Q

Cone or rods?

Function optimally in dark adaptation

A

Rods

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6
Q

Axons from ganglion cells of nasal retina of each eye (cross/do not cross) in the ____

A

Cross

optic chiasm

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7
Q

Nasal retina receives visual information from ____

A

temporal visual field

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8
Q

Temporal retina receive visual information from ___

A

nasal visual field

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9
Q

superior retina receives information from ____

A

inferior visual field

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10
Q

Visual information pass through ____ from retinal ganglion cells to primary visual cortex

A

Lateral geniculate nucleus (LGN) of the thalamus

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11
Q

Axons of ipsilateral retinal ganglion cells synapse in ___

A

layers 2, 3, 5 of lateral geniculate nucleus

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12
Q

Axons of contralateral retinal ganglion cells synapse in ___

A

Layers 1, 4, 6 of lateral geniculate nucleus

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13
Q

Magnocellular pathway are composed of layer ____ of LGN

Concerned with:

A

1 and 2

movement detection, detection of low contrast, dynamic form perception

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14
Q

Parvocellular pathway composed of ___ layers of LGN

Concerned with:

A

3 and 6

Color selective and responsive to high contrast

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15
Q

Most peripheral temporal visual field arises from (paired/unpaired) (crossed/uncrossed) axons from the (nasal/temporal) retina that projects to ____

A

Unpaired
Crossed
Nasal
Most anteromedial portion of visual cortex

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16
Q

Macular disease produces ____

A

hemeralopia (day blindness)

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17
Q

Peripheral retinal disease produces ____

A

Nyctalopia (night blindness)

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18
Q

Diseases of optic nerve produces (3):

A

Central vision loss: decreased visual acuity w/ central scotoma
Impaired color vision
Impaired contrast vision

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19
Q

Cardinal sign of optic nerve disease

A

Relative afferent pupillary defect: affected pupil will dilate when illuminated in swinging flashlight test

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20
Q

Disease of optic chiasm produce:

A

Bitemporal hemianopia = temporal visual field defect

b/c only crossing fibers from nasal retina affected

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21
Q

Disease affecting retrochiasmal visual pathway produces:

A

Homonymous hemianopia = visual field defect of same half of the visual field in bowth eyes

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22
Q

Diseases affecting superior fibers produce:

A

homonymous inferior quadrantanopia = visual field defect of same inferior quarter of visual field in both eyes

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23
Q

Ventral pathway of primary visual cortex is involved in:

A

Object identification and recognition

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24
Q

dorsal pathway of primary visual cortex is involved in:

A

Visual information to aid in object localization in space

25
Q

Prosopagnosia

A

Inability to recognize faces

26
Q

Action of superior rectus

A

Elevation and intorsion

27
Q

Action of inferior rectus

A

Depression and extorsion

28
Q

Action of superior oblique

A

Depression and intorsion

29
Q

Action of inferior oblique

A

Elevation and extorsion

30
Q

CN3 nucleus located:

A

midbrain, ventral to cerebral aqueduct

31
Q

Motor neurons for levator palpebrae superioris m. arise from:

A

central caudal nucleus (midline)

32
Q

Motor neurons for superior rectus m. arise from:

A

CONTRALATERAL superior rectus subnucleus

33
Q

Motor neurons for remaining extraocular m of CN3 arise from:

A

Ipsilateral subnuclei

34
Q

CN4 nucleus located:

Motor neurons destined for superior oblique m. arise from:

A

dorsal-caudal midbrain

CONTRALATERAL CN4 nucleus

35
Q

CN6 nucleus located in:

Contain motor neurons destined for (ipsi/contralateral) lateral rectus m.

A

Pontine tegmentum

Ipsilateral

36
Q

3rd Nerve Palsy results in:

A

Impaired elevation, depression, adduction
Inability to open eyes
Dilated pupils

37
Q

When looking straight ahead, pt with 3rd nerve palsy will have:

A

eye that deviates away from nose and downward (down and out)

38
Q

Common causes of 3rd nerve palsy (2)

A

Microvascular ischemia

Compression by posterior communicating artery aneurysm

39
Q

Compression by posterior communicating artery aneurysm will cause:

Rule of pupil:

A

dilation of pupil b/c parasymp. fibers to sphincter m. are located peripherally and dorsally in nerve.

Rule of the pupil: When CN3 is compressed by aneurysm, pupil wil dialate and/or sluggishly reactive.

40
Q

Microvascular ischemia causing 3rd nerve palsy will affect:

A

Center of nerve, sparing pupil constriction

41
Q

4th Nerve Palsy results in:

A

Impaired depression and intorsion of eye, especially when eye is adducted

42
Q

Pt with 4th nerve palsy will tilt head to (ipsi/contralateral) side to compensate for impaired intorsion.

A

Contralateral

43
Q

6th Nerve Palsy will result in:

A

impaired abduction of eye

44
Q

Common cause of 6th nerve palsy

A

Alterations in intracranial pressure

Head trauma

45
Q

Frontal eye fields located at:

Signals:

A

caudal end of middle frontal gyrus

Contralateral voluntary saccades
Contralateral smooth pursuts and vergence eye movements

46
Q

Unilateral lesion of frontal eye fields will result in:

A

Ipsilateral gaze deviation

Loss of ability to produce contralateral voluntary saccades

47
Q

Bilateral lesions of frontal eye fields will result in:

A

Ocular motor apraxia = Inability to produce voluntary saccades appropriately

48
Q

Parietal eye fields located in:

Signals:

A

Lateral intraparietal sulcus

Visual-evoked saccades
Smooth pursuit

49
Q

Omnipause neurons located in:

A

Nucleus raphe interpositus in pontine reticular formation

50
Q

Constant stimulation of omnipause neurons result in:

A

inability to generate saccades

51
Q

Neurons responsible for horizontal saccades are located in:

A

Pons in paramedian pontine reticular formation (PPRF)

52
Q

Neurons responsible for vertical-torsional saccades are located in:

A

rostral midbrain in rostral interstitial nucleus of medial longitudinal fasciculus (riMLF)

53
Q

Lesion of PPRF will result in:

A

Slowing/complete inability of ipsilateral horizontal saccades
Gaze deviation to contralateral side
Ipsilateral facial palsy

Horizontal VOR remains intact

54
Q

Lesion of MLF will result in:

A

Slowing/complete inability to adduct ipsilateral eye during contralateral saccades

55
Q

Bilateral lesion of riMLF will:

A

abolish all vertical saccadic eye movements

Vertical VOR remains intact

56
Q

Horizontal component of step signal produced by:

A

medial vestibular nuclei

nucleus prepositus hypoglossi

57
Q

Vertical and torsional component of step signal produced by:

A

Interstitial nucleus of Cajal in midbrain reticular formation

58
Q

Lesions of neural integrator will produce:

A

Gaze-evoked nystagmus: Drift of eye back to center that’s corrected for by saccadic eye movements back to object of interest

59
Q

Instability of neural integrator results in:

A

Pendular nystagmus = eye oscillations

60
Q

Lesion in interstitial nucleus of Cajal will result in:

A

Seesaw nystagmus = vertical and torsional oscillations

61
Q

Near response triad

A
  1. Convergence of eyes
  2. Accommodation of lens
  3. Constriction of pupil (miosis)

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