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PNS > Unit 2 > Flashcards

Unit 2 Flashcards

1
Q

What are the primary sensory neurons of the Olfactory nerve?

A

olfactory neurons

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2
Q

True or false: olfactory neurons are unipolar.

A

false, they are bipolar

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3
Q

Where can the olfactory neurons be found?

A

in the olfactory epithelium that lines the superior part of the nasal cavity

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4
Q

What are olfactory neurons supported by?

A

“supporting cells”

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5
Q

What is the function of olfactory hairs?

A

receptors

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6
Q

Central process collect how many olfactory nerves?

A

10-20

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7
Q

Where do the central processes that collect the olfactory nerves convey their information?

A

olfactory bulbs

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8
Q

True or false: olfactory nerves are unmyelinated.

A

True; however, they are covered by Schwann cells

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9
Q

Where does the olfactory nerve cross into the skull?

A

cribiform plate of the ethmoid bone

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10
Q

After entering the olfactory bulb, where do the olfactory nerves synapse?

A

on the dendrites of mitral cells

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11
Q

What are formed where the olfactory nerve synapses on the mmitral cells?

A

synaptic glomeruli

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12
Q

What are the secondary sensory neurons to the Olfactory nerve?

A

Mitral Cells

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13
Q

Where are mitral cells located?

A

in the olfactory bulb

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14
Q

Mitral cells relay information posteriorly via which tract?

A

olfactory tract

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15
Q

What happens to the tract fibers of the olfactory nerve pathway at the anterior perforated substance?

A

the fibers split into medial and lateral olfactory striae

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16
Q

How does the medial stria fibers of the olfactory pathway get to the opposite olfactory bulb?

A

They cross the midline via the anterior commisure

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17
Q

Where do the lateral stria fibers carry information to?

A

1) Primary Olfactory Cortex

2) secondary olfactory cortex

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18
Q

What is included in the primary olfactory cortex?

A

perimygdaloid area, prepiriform area, and uncut (bdmn area 34)

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19
Q

What is included in the secondary olfactory cortex?

A

entorhinal area in parahipocampal gyrus (bdmn 28)

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20
Q

How many neurons does it take to get from the receptor to the cortex in the olfactory pathway?

A

2

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21
Q

What structure does the olfactory pathway not synapse in?

A

thalamus

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22
Q

Which autonomic nerve of the olfactory pathway travels from the nasal septum?

A

terminal nerve

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23
Q

Which nerve of the olfactory pathway is poorly developed in humans but used for tracking prey?

A

vomeronasal nerve

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24
Q

What are possible clinical considerations for the olfactory pathway?

A
  1. anosmia (loss of smell)
  2. skull fractures (cribiform plate damage)
  3. CSF leakage
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25
Q

What are the three layers of the eyeball?

A

Fibrous tunic
Vascular Tunic
Retina
(in order from outermost to inner)

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26
Q

What does the Vascular tunic consist of? (middle layer)

A

ciliary body, iris, choroid

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27
Q

What does the fibrous tunic consist of? (outermost layer)

A

sclera and cornea

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28
Q

The innermost layer (Retina) consists of 10 layers; what are they?

A

pigmented layer, photosensitive outer segments of rods and cones, external limiting membrane, outer nuclear layer (rods and cones), outer plexiform layer(rods and cones synapse with bipolar cells), inner nuclear layer (cell bodies of bipolar cells), inner plexiform layer (bipolar cells synapse with ganglion), ganglion cell layer, nerve fiber layer, internal limiting membrane

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29
Q

What is the function of the cones in the photoreceptors?

A

receive color information (require adequate light to function best)

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30
Q

Where would cones be more concentrated?

A

towards the center of the retina

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31
Q

What is the function of the rods in photoreceptors?

A

they only sense light and dark

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32
Q

Where would you find the most rods?

A

In the periphery of the retina. There are no rods in the fovea

33
Q

When photoreceptor cells are depolarized, where do they relay information?

A

bipolar cells in the outer plexiform layer

34
Q

Where do bipolar cells of the Optic pathway relay their information?

A

they synapse in the inner plexiform later, relaying information to ganglion cells

35
Q

Axons form the ganglion cells are conveyed in the nerve fiber layer toward to optic disc. After leaving the eyeball what carries these axons?

A

The optic nerve

36
Q

After optic nerves enter the skull via the optic canal, they unite to form what?

A

optic chiasma

37
Q

True or False: optic nerves are myelinated

A

True; oligodendrocytes form the myelin

38
Q

True or False: In the optic chiasma, all fibers cross.

A

False, fibers from the medial sides of the retina will cross but the fibers from the lateral sides of the retina will not.

39
Q

The optic tract travels around the cerebral peduncles and fibers can synapse on which three nuclei of termination?

A

lateral geniculate body
superior colliculus
pretectal nucleus of the midbrain

40
Q

Which nuclei of termination that the optic tract can synapse on is the most common?

A

lateral geniculate body which then relays information to the cerebral cortex in the occipital lobe (Brodmann area 17)

41
Q

What happens to the optic tract fibers that synapse in the superior colliculus?

A

information is relayed to the techtospinal tract

42
Q

What two muscles are influenced by the techtospinal tract?

A

trapezius and sternocleidomastoid

43
Q

What is the function of the optic tract fibers that synapse in the pretectal nucleus of the midbrain?

A

they deal with light reflexes

44
Q

What would cause a patient to lose vision in one eyeball?

A

lesion on the optic nerve

45
Q

what would cause a patient to have tunnel vision?

A

a lesion in the optic chiasma

46
Q

What would cause a patient to lose half of his visual field? (affects half of both eyes)

A

lesion to the optic tract

47
Q

What are the four visual reflexes?

A
  1. direct and consensual light reflex (afferent only)
  2. accommodation reflex
  3. corneal reflex
  4. convergence (cross eyes)
48
Q

Which nerve supplies motor to all extraocular muscles besides superior oblique and lateral rectus?

A

CN III, Oculomotor

49
Q

What part of the cerebral cortex sends axons to the oculomotor nuclei?

A

Brodmann area 8

50
Q

Where does the oculomotor nuclei receive fibers from?

A

the superior colliculus and medial longitudinal fasciculus

51
Q

Where are the somatic nuclei of origin of the oculomotor nuclei located?

A

the periaqueductal gray matter

52
Q

Axons of the occulomotor nerve travel through the red nucleus and exit the CNS through which opening?

A

interpeduncular fossa into the cistern

53
Q

When the oculomotor fibers exit the CNS what is the nerve covered by?

A

Schwann cells

54
Q

After penetrating the dura mater, what does the oculomotor nerve travel along before exiting the skull?

A

cavernous sinus

55
Q

Once the oculomotor nerve is in the eye socket (via superior orbital fissure) the nerve splits into _________ and ________.

A

Superior and Inferior ramii

56
Q

The superior ramus of the oculomotor nerve supplies which muscles?

A

superior rectus and levator palpebrae superioris

57
Q

The inferior rams of the oculomotor nerve supplies which muscles?

A

medial branch of medial rectus
central branch of inferior rectus
lateral branch of inferior rectus

58
Q

Which oculomotor nucleus contains preganglionic parasympathetic neurons?

A

accessory oculomotor nucleus

59
Q

Where do the axons of the accessory oculomotor nucleus synapse?

A

the ciliary ganglion where the post ganglionic parasympathetic axons follow the course of ciliary arteries.

60
Q

After the post ganglionic parasympathetic axons of the accessory oculomotor nucleus pierce the sclera, what muscles do they supply?

A

Ciliaris and pupillary contrictor

61
Q

What does CN IV (trochlear never) supply?

A

the somatic motor nerve supply of the superior oblique muscle

62
Q

Where is the trochlear nucleus located?

A

In the periaqueductal gray, just causdal to the oculomotor nuclei

63
Q

What part of the cerebral cortex sends axons to the trochlear nucleus?

A

Brodmann area 8

64
Q

Where does the trochlear nucleus receive fibers from?

A

superior colliculus and medial longitudinal fasciculus

65
Q

What does the trochlear nerve communicate with?

A

the Cavernous plexus

66
Q

What is the trochlear nerve named for?

A

the pulley-like mechanism on the supero-medial aspect of the orbit that superior oblique muscle passes through

67
Q

What does the Abducens nerve (CN VI) supply?

A

somatic nerve supply to the lateral rectus muscle

68
Q

Where is the abducens nucleus located?

A

in the caudal part of the pons, at the floor of the rhomboid fossa

69
Q

How do axons leave the abducens nucleus?

A

they project anterior wars and exit the CNS at the inferior border of the pons and MO

70
Q

From which parts of the CNS does the abducens nerve receive information?

A

Brodmann area 8, superior colliculus, and the medial longitudinal fasciculus

71
Q

How does the abducens nerve get to the lateral rectus muscle?

A

it penetrates the dura, travels along the cavernous sinus, and exits the skull throughout the superior orbital fissure

72
Q

What are the two types of strabismus?

A
  1. internal- eye cross (converge)

2. Exernal- eyes are directed away from each other (diverge)

73
Q

What is diplopia?

A

double vision; very subjective and difficult to demonstrate

74
Q

What is Ptosis?

A

eyelid droop due to weakness of the legator palpebrae superioris

75
Q

What might cause Ptosis (eyelid droop)?

A

oculomotor lesion

76
Q

What is Trochlear paralysis?

A

internal strabismus; inability to look down

77
Q

What might someone with trochlear paralysis have trouble doing?

A

descending stairs

78
Q

What is abducens paralysis

A

internal strabismus (more common than trochlear paralysis)

79
Q

What is internuclear opthalmoplegia?

A

it involves damage to the medial longitudinal folliculus

nystagmus in abducting eye

PNS (11 decks)

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