The olfactory nerve is the first Cranial nerve and is responsible for the sense of smell. It consists of the fila olfactoria, which are fine nerve fibers involved in olfactory perception[^1].
Anatomy
The fila olfactoria consist of approximately 20-25 small bundles of unmyelinated nerve fibers. They conduct electrical impulses from olfactory receptor cells in the regio olfactoria of the nasal mucosa through the lamina cribrosa of the ethmoid bone and terminate primarily on the dendrites of mitral cells in the olfactory bulb. The impulses are then transmitted via the olfactory tract in the olfactory peduncle to the olfactory trigone on the basal surface of the brain and from there to the primary olfactory cortex.
Clinical testing
The function of the olfactory nerve can be tested using a smell test.
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Pathology
In patients with traumatic brain injury, avulsion of the fila olfactoria may occur, resulting in loss (Anosmia) or reduction (Hyposmia) of the sense of smell. Meningiomas may also develop in the region of the olfactory bulb (Olfactory groove meningiomas), which can likewise lead to impairment of the sense of smell.