Unit II - Olfactory Nerve Flashcards
What are olfactory neurons?
Primary sensory neurons
What kind of neuron is the olfactory neuron?
Bipolar
Where are the olfactory neurons found?
In the epithelium lining the superior part of the nasal cavity.
What covers the olfactory epithelium?
A thin layer of mucous
Olfactory neurons are supported by what kind of cells?
Supporting cells
Olfactory _____ function as receptors.
hairs
About how many olfactory neurons convey information to the olfactory bulb?
10-20
What make up the 10-20 olfactory nerves?
Central processes (axons) bundled together
Are olfactory neuron axons myelinated or unmyelinated?
unmyelinated
What are olfactory neurons covered by?
Schwann cells
Olfactory nerves pass through what? Which bone is this part of?
cribriform plate
ethmoid
When the olfactory neurons pass through the cribriform plate what to they enter into?
The olfactory bulb
When the neurons enter the olfactory bulb what do they synapse on?
The detritus of mitral cells
What are formed at these synapses between the olfactory neurons and mitral cells in the olfactory bulb?
Synaptic glomeruli
Where is the cell body for the olfactory neuron?
In the nasal cavity (superior)
What is another name for the olfactory nerve?
fila olfactoria
What stimulates the olfactory neuron?
chemoreceptors
Mitral cells are what type of neurons?
Secondary sensory neurons
Where are mitral cell bodies located?
in the olfactory bulb
Mitral cells relay information in what direction?
posterior
Mitral cells relay information via the _____?
Olfactory tract
At what area do the tract fibers split?
Anterior perforated substance
What doe the tract fibers split into?
Medial and lateral striae
What do the medial stria fibers do?
They cross the midline
Where do the medial stria fibers cross the midline?
At the anterior commissure
Where do the medial stria fibers travel to?
The opposite olfactory bulb
Do the lateral stria fibers cross over?
no
Where do the lateral stria fibers carry information to?
primary olfactory cortex
periamygdaloid area
prepiriform area, including the uncus
The uncus is Broadmann area what?
34
Where is the uncus located?
Medial aspect of the temporal lobe.
What does it mean clinically that some of the fibers cross over to the other side.
Poor ability to segregate R/L smelling.
What is the bridge where the two olfactory tracts come together called?
Anterior commissure
How many neurons long is the olfactory pathway?
2
The olfactory pathway is a 2 neuron pathway. An exception to the normal 3 neuron pathways. What is different about this pathway?
It bypasses the thalamus - DOES NOT SYNAPSE in the thalamus!
What is the total loss of smell called?
anosmia
What are two things to know about anosmia?
It’s rare and usually congenital
What else can cause smell problems?
Skull fractures and CSF leakage
What are two other pathways concerning the olfactory nerves?
Terminal nerve and vomeronasal nerve
Is the vomeronasal nerve developed well in humans?
NO - poorly developed, used mainly to track prey in animals
What is the terminal nerve for and where is it located?
autonomic (visceral) function, on nasal septum
What causes CSF leakage here?
A tear in the dura mater
