lecture 14: CN 1 and 2 Flashcards
what is cranial n 1
olfactory
is the olfactory n sensory, motor, or both
sensory
thru what foramina does CN 1 pass thru
cribriform plate (ethmoid bone)
true or false: the cranial n 1 (olfactory) does not emerge from the brainstem
true
where are the cell bodies located for the olfactory n
in olfactory epothelium
does the olfactory n have a brainstem nuclei
no
what is the associated foramen of the olfactory n
foramina of cribriform plate (ethmoid bone)
what is general function of the olfactory n
olfaction/smell
the olfactory n is a collection of what types of neurones
bipolar neurons
where is the cell bodies of primary neurons of olfactory n located
in olfactory epithelium
what acts as sensory receptors for the olfactory n
cilliated peripheral processes
where do the cilliated peripheral processes (that act as sensory receptors) sit for the olfactory n
in olfactory mucuso (receptors face inside the nasal cavity)
where do the central processes of the olfactory n pass
thru foramina of cribifriom plate
what are the 2 cells that support the primary sensory neurons of the olfactory n
basal cells and sustentacular cells
where do primary neurons synapse with secondary neurons for olfactory n
in olfactory build
where are the secondary sensory neuron cell bodies located for the olfactory n
in olfactory bulb
what do the axons of the secondary olfactory neurons form
olfactory tract and trigone
why is the synapse between primary and secondary olfactory neurons different than usualy
happens in spherical shape (glomerulus)
what gives the olfactory burn its large and circular shape
the cell bodies of the secondary n
what is anosmia
loss of smell
loss of smell is called what
anosmia
what is hyposmia
reduced ability to smell
reduced ability to smell is called what
hyposmia
what are some causes for anosmia or hyposmia
congestion or swelling of mucosa (usually transient)
shearing of fibers passing thru crib plate (usually w head trauma)
lesions or damages along the pathways
is there any decussation in the olfactory pathway
no , olfactory info is relayed to ipsilateral primary olfactory cortex
exp:the medial stria to contralateral oflactory bulb
olfactory info is relayed to ipsilateral or contra later primary olfactory cortex
ipsilateral
true or false: there is decussation of olfactory system
false, there is none since olfactory info is relayed to ipsilateral primary olfactory cortex
what is the olfactory trigone
it is a division of the olfactory tract into a medial olfactory stria and a lateral olfactory stria
what is the function of dividing the olfactory tract into a medial and lateral olfactory stria
since some neurons form the medial olfactory stria to cross the midline (via ant comissiure and inhibit the contralateral olfactory bulb)
=assists in localization of smell
what assists in localization of smell
the fact that some neurons form the medial olfactory stria to cross the midline (via ant comissiure and inhibit the contralateral olfactory bulb)
how do some neurons form the medial olfactory stria to cross the midline
(via ant comissiure
what is the physiological function of some neurons forming the medial olfactory stria to cross midline
to inhibit the contralateral olfactory bulb (assists with localization of smell)
describe the location of the primary olfactory cortez
piriform area (uncut and anterior parahippocampal gyrus)
does the piriform cortex have any important connections for the olfactory system
yes, projects to adjacent limbic area, including strong connections to the amygdala
=explains how there are memories linked to olfactory cues
since the piriform area projects to adjacent limbic area, including strong connections to the amygdala
what does this explain
=explains how there are memories linked to olfactory cues
true or false: vision is the only system of concious somatosensation that does not HAVE to pass thru the thalamus on its way to primary cortex
false, olfacttion
explain why there is no tertiary neuron involved in olfaction
since it is is the only system of concious somatosensation that does not HAVE to pass thru the thalamus on its way to primary cortex
what is the function of the “secondary” olfactory system
concious perception and discrimination of olfactory information
does info from the olfactory system never go to the thalamus
false, it can go there (just doesn’t HAVE TO)
what is the cortex that allows us to discriminate olfactory info
discriminative olfactory cortex (secondary olfactory cortex) in orbitofrotal cortex (ant region)
where is the discriminative olfactory cortex (secondary olfactory cortex) located
in orbitofrotal cortex (ant region)
explain the thalamic relay of olfactory system
information from piriform area can project to thalamus (speficially to the dorsomedial nucleus) before going to orbitofrontal cortex
what is the important thalamic nucleus for olfactoion
dorsomedial nucleus
what does damage to the secondary olfactory cortex lead to (either to that thalamic relax/orbitfrontal cortex)
difficulty identifying and or discriminating between smells (can still detect presence of doors)
in a damage to secondary olfactory cortex, can you still detect present of odours
yes
contrast a lesion/damage to primary olfactory cortex to secondary
primary: complete loss of smell (asnosmia)
secondary: difficulty identifying and or discriminating between smells (can still detect presence of doors)
what are the 2 important olfactory reflexes
secretion of saliva in response to appetizing smells
promotion of digestive processes
true or false: olfactory pathways have limited projections to the diencephalon
false, wide-spears projectsios including to the diencephalon
explain the secretion of saliva in response to appetizing smells reflex
projections from habenular nuclei (epithalamus) thru stria medullar is and hypothalams
target= superior (CN VII) and inferior (CN IX) salivary nuclei
what are the important dice-halon structures of the secretion of saliva reflex
projections from habenular nuclei (epithalamus) and hypothalams
what is the target for the secretion of saliva in response to smells reflex
superior (CN VII) and inferior (CN IX) salivary nuclei
what is the cranial n associated with the superior salivary nuclei
CN VII)
what is the cranial n associated with the inferior salivary nuclei
CN IX
explain the promotion of digestive processes reflex
projections from hypothalamus
targer=dorsal motor nucleus of the vagus N (X)
=going to project to various digestive tissues to increase perilsatlic activity, gastric secretion, warming system
what is the important diencephalon structure for the promotion of digestive processes reflex
hypothalamus
what is the important target structure for the promotion of digestive processes reflex
dorsal motor nucleus of vagus N (CN X)
is the optic n sensory, motor or both
sensory
is the optic n associated with a brainstem nuclei
no
where are the cell bodies of primary neurons for optic n located
in retina (ganglion cells)
what is the associated foramen for the optic ne
optic foramen/canal (sphenoid bone)
what is the function of the optic n
vision
how many cranial nerves are associated in visual processes
4
what are the 4 cranial nerves associated in visual processes
CN II
CN III, IV, VI
explain how CN II is associated in visual processes
transmission of visual information
explain how CN III, IV, VI is associated in visual processes
movement of the eye
is optic n part of the PNS or CNS
CNS
what is the optic n
bundle of retinal ganglion cell axons
are the bundle of retinal ganglion cell axons bipolar or multipolar
bipolar
where are the cell bodies of the optic n located
in inner later of retina
what is the pathway of visual information coming in to retina
information has to pass to the deepest structure first (perceived by photoreceptors) beforee getting pushed back towards bipolar cells, then retinal ganglion cells
are the bundle of retinal ganglion cell axons more analogous ti secondary or primary sensory neurons and explain
secondary
(they decussate and synapse in the thalamus)
are we going to see a 3 neuron pathway in the optic/visual system
not really.. optic nerve kinda starts at secondary neuron
what is the most analogous to a primary neuron in the visual system
bipolar cells
what is the fovea
central fixation point (highest visual acuity where there is the max concentration of photoreceptors)
central fixation point (highest visual acuity where there is the max concentration of photoreceptors)
is called the
fovea
what is the macula
the surrounding area to the fovea with a still high amount of photoreceptors
where do the retinal ganglion cells exit the eye
optic disk
true or false; the optic disk has photorecepors
false, it is a blind spot (optic n exits here)
true or false: each eye has both a right and a left visual field
true
do the visual fields of right and left eyes overlap
yes, overlap to form a central binocular region and lateral monocular regions
true or false: left eye=left visual field
false
in the left eye, is the right visual field more nasal or temporal
nasal
in the left eye, is the left visual field more nasal or temporal
temporal
in the right eye, is the right visual field more nasal or temporal
temporal
in the right eye, is the left visual field more nasal or temporal
nasal
what happens to information from the visual field when it hits the retina
info is inverted from horizontally and vertically
explain how in the retinae, info from visual field is inverted from horizontally and vertically
anything coming from lateral/temporal visual fields will be on nasal side of retina and vice versa
anything that was at the top of the visual field, will be at the bottom of the retina
explain the decussation that occurs at the optic chiasm
nerve fibers from the medial/nasal half of the retina decussate to the contralateral side
nerve fibers from the lateral/temporal half of the retina stay ipsilateral
explain the pathway of nerve fibers from the medial/nasal half of the retina
nerve fibers from the medial/nasal half of the retina decussate to the contralateral side
explain the pathway of nerve fibers from the lateral/temporal half of the retina
stay ipsilateral
true or false: nerve fibers from the temportal/lateral half of the retina decussate to the contralateral side
false, they stay ipsilateral
left visual field information in left eye will end up on what side of the retina, and what side of the optic tract
will end up on medial/nasal aspect of the retina
that means the fibres will decussate and end up in right optic tract
right visual field information in left eye will end up on what side of the retina, and what side of the optic tract
will end up on lateral/temporal aspect of the retina
that means the fibres will not decussate/stay ipsi and end up in left optic tract
left visual field information in right eye will end up on what side of the retina, and what side of the optic tract
will end up on temporal/lateral aspect of the retina
that means the fibres will not decussate/stay ipsi and end up in right optic tract
right visual field information in right eye will end up on what side of the retina, and what side of the optic tract
will end up on medial/nasal aspect of the retina
that means the fibres will decussate and end up in left optic tract
which fibers decussate: medial or lateral
medial
all information from left eye ends up in what optic n
left optic n
all information from right eye ends up in what optic n
right optic n
what is the point ofnthe decussation at optic chiasm
reorganization of information so that all information from left visual field will be on right side of brain
and all info from right visual field will be on left side of brain
when you get to the optic tract, all information from right visual field is on what side
left optic tract
what is the next stop of secondary neurons of optic pathway after the optic tract
lateral geniculate nucleus of the thalamusw
what is the important nucleus of the thalamus for visual pathway
lateral geniculate nucleus of the thalamus
what is the terminal synapse for most retinae ganglion neurons
lateral geniculate nucleus of the thalamus
HOW MANY layers of lateral geniculate nucleus
6
information coming from ipsilateral eye in LGN of thalamus goes to what layers
2,3,5
information coming from contral eye in LGN of thalamus goes to what layers
1,4,6
layers 2,3,5 of LGN of thalamus is associated with contralateral or ipsialtearl eye
ipsilateral
layers 1,4,6 of LGN of thalamus is associated with contralateral or ipsialtearl eye
contralateral
input from rods go to what layers
magnocellular (1,2)
magnocellular (1,2) layers is input from rods or cones
rods
input from cones go to what layers
parvocellular ()3-6)
parvocellular ()3-6) layers is input from rods or cones
cones
example the parvocellular (3-6) organization
high spacial resolution and low temporal resolution = important for acuity and colour
explain the magnocellular (102) orgnization
low spacial resolution and high temporal resolution = important for contrast and movement
after synapsing in the LGN of the thalamus, tertiary sensory neurons form what in the brain
optic radiation (geniculocalcarine tract)
explain the retinotopic organization of the optic radiation
information from upper visual quadrant travels in temporal raditions (lower) (including meyers loop)
information from lower visual quadrant travels in parietal raditations
information from upper visual quadrant travels in BLANK raditations
temporal
information from lower visual quadrant travels in BLANK raditations
information from lower visual quadrant travels in parietal raditations
where does visualsensory info end in the brain
primary visual cortex (in and around calcarine sulcus)
where is the primary visual cortex located
in and around calcarine sulcus
explain the 3 retinotopic organizations of the primary visual cortex
1) information from left visual field goes to right visual hemispheres (vice versa)
2) information from upper quad ends up below calc sulcus
while info from lower quads ends up above calcarine sulcus
3) information from the centre of visual field (fovea) is most caudal
as we move more rostral within the primary visual cortex information willl become more periphere
explain the side (R/L) retinotopic organization
1) information from left visual field goes to right visual hemispheres (vice versa)
explain the quadrant (U/L) retinotopic organization
2) information from upper quad ends up below calc sulcus
while info from lower quads ends up above calcarine sulcus
true or false: 2) information from upper quad ends up below calc sulcus
true
explain the proximity to fovea retinotopic organization
information from the centre of visual field (fovea) is most caudal
as we move more rostral within the primary visual cortex information willl become more periphere
information from centre of visual field is more caudal or rostral
caudal
information from perioherals of visual field is more caudal or rostral
rostral
why do we get the meyers loop for termporal radiations
must go around the inferior horn of lateral ventricles
information from upper quadrant travels in temporal radiations and goes to what part ocf occipital
below the calcarine sulcus
information from lower quadrant travels in parietal radiations and goes to what part ocf occipital
above the calcarine sulcus
