Everything about The Olfactory Nerve totally explained
The
olfactory nerve, or
cranial nerve I, is the first of twelve
cranial nerves. The specialized
olfactory receptor neurons of the olfactory nerve are located in the olfactory
mucosa of the upper parts of the
nasal cavity. The olfactory nerves don't form two trunks like the remaining cranial nerves, but consist of a collection of many sensory nerve fibers that extend from the olfactory epithelium to the
olfactory bulb, passing through the many openings of the Cribriform plate of the Ethmoid bone; a
sieve-like structure.
Olfactory receptor neurons continue to be born throughout life and extend new axons to the
olfactory bulb. Olfactory ensheathing glia wrap bundles of these axons and are thought to facilitate their passage into the central nervous system.
The sense of
smell (olfaction) arises from the stimulation of the olfactory receptors by activation from gas molecules that pass by the nose during respiration. The resulting electrical activity is
transduced into the olfactory bulb which then transmits the electrical activity to other parts of the
olfactory system and the rest of the
central nervous system via the olfactory tract.
The olfactory nerve is the shortest of all the twelve cranial nerves and only one of two cranial nerves (the other being the
optic nerve) that don't join with the
brainstem.
Testing the Olfactory nerve
To test the function of the olfactory nerve, doctors block one of the patient's nostrils and place a pungent odor (such as damp coffee essence) under the open nostril. The test is then repeated on the other nostril.
Lesions of the Olfactory nerve
Lesions to the Olfactory nerve often lead to a reduced ability to taste and smell. However, ammonia can still be detected by the pain fibers of the Trigeminal nerve. They can occur because of blunt trauma, such a coup-contra-coup damage, meningitis and tumors of the frontal lobe.
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