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)