CN I Olfactory Flashcards
Olfactory nerves are often described as an extension of what system?
Central nerve system
The primary olfactory neurons are what type of neurons?
Bipolar
Where are primary olfactory neurons located?
In olfactory epithelium or mucosa on the superior nasal concha and the adjacent part of the ethmoidal perpendicular plate
What is below the perpendicular plate?
Septal cartilage
What is the superficial end of the olfactory neuron that slightly extends beyond the surface of the epithelium?
Olfactory vesicle
Each olfactory vesicle is attached by many of these
Olfactory cilia
What is the function of olfactory cilia?
Detect odorant
This is 15-20 bundles of nerve fibers of olfactory neurons
Fila olfactoria
The fila olfactoria passes through what opening of bone?
Cribriform plate of ethmoid
What are the secondary olfactory neurons that the fila olfactoria synapse with?
Mainly mitral cells and some tufted cells in the olfactory bulb
How long do we keep olfactory receptor neurons for?
They are continually replaced
List the layers of the laminar structure beginning at the surface working inward
Olfactory nerve layer, glomerular layer, external plexiform layer, mitral cell layer, internal plexiform layer, granule cell layer, and nerve fibers tract
This layer consists of unmyelinated axons of the olfactory neurons
Olfactory nerve layer
This layer has a thin sheet of glomeruli where the incoming olfactory axons divide and synapse on terminal dendrites of secondary neurons
Glomerular layer
Name some secondary olfactory neurons in the glomerular layer
Mitral, tufted, and periglomerular cells
This layer contains the principal and secondary dendrites of mitral and tufted cells
External plexiform layer
In the mitral layer, each cell sends a single principle dendrite to where?
Glomerulus
In the mitral layer, each cell sends a secondary dendrites to where?
External plexiform layer and a single axon to the olfactory tract
The mitral layer contains a few granule cells bodies which form this
Nucleus of termination
This layer contains axons, recurrent and deep collaterals of mitral cells, tufted cells, and granule cell bodies
Internal plexiform layer
This layer is extended into the olfactory tract as scattered medium-sized multipolar neurons
Granule cell layer
The multipolar neurons of the granule cell layer constitute what?
Anterior olfactory nucleus
The olfactory tract extends to the anterior olfactory nucleus to form this
Olfactory trigone
What does the trigone split into?
Medial and lateral olfactory striae
What are the principal neurons in the olfactory bulb?
Mitral and tufted cells
Which two cells make up the main intrinsic neuron in the bulb?
Periglomerular and granule cells
These cells distribute their axons laterally and terminate within extraglomerular regions
Periglomerular cells
These cells have no axon, ramify and terminate in the external plexiform layer, and have a powerful inhibitory influence on the output neurons of the bulb
Granule cells
Once the medial striae cross the median plane in the anterior commissure, where does it end?
Subcallosal area
What does the subcallosal area consist of?
Parolfactory and paraterminal area
The subcallosal area is connected with the parahippocampal gyrus by way of what?
Cingular gyrus
The lateral striae continues into this gyrus
Gyrus semilunaris
What area does the lateral striae end?
Entorhinal area
What does the lateral striae pass on its way to the entorhinal area?
The parahippocampal gyrus, amigdaloid body, uncut, and piriform area on the medial aspect of the temporal lobe
What brodmann area is the uncut?
Brodmann area 34
The olfactory brain
Uncus
The uncus is connected with the visceral brain through this
Fornix
Describe the olfactory fibers as a whole
They are minute and devoid of any covering
Damage to any part of the olfactory system may result in what?
Hyposmia or anosmia
