Olfactory nerve 196434 220250161 2008-06-18T23:32:08Z Eeekster 5583074 Reverted edits by [[Special:Contributions/68.192.77.22|68.192.77.22]] ([[User talk:68.192.77.22|talk]]) to last version by ClueBot {{Infobox Nerve | Name = {{PAGENAME}} | Latin = nervus olfactorius | GraySubject = 196 | Image = Gray771.png | Caption = | Innervates = | BranchFrom = | BranchTo = | MeshName = Olfactory+Nerve | MeshNumber = A08.800.800.120.640 | }} The '''olfactory nerve''', or '''cranial nerve I''', is the first of twelve [[cranial nerve]]s. The specialized [[olfactory receptor neuron]]s of the olfactory nerve are located in the olfactory [[mucosa]] of the upper parts of the [[nasal cavity]]. The olfactory nerves do not 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 neuron]]s 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 [[olfaction|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 [[transduction (physiology)|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 do not 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. ==Additional images== <gallery> </gallery> ==See also== * [[Anterior olfactory nucleus]] ==External links== * {{YaleCranialNerves|1|1}} * {{NormanAnatomy|cranialnerves}} ({{NormanAnatomyFig|I}}) {{Cranial nerves}} {{Olfactory_system}} [[Category:Central nervous system]] [[Category:Olfactory system]] [[Category:Cranial nerves]] [[ar:عصب شمي]] [[de:Nervus olfactorius]] [[fr:Nerf olfactif]] [[hr:Njušni živci]] [[it:Nervo olfattivo]] [[lt:Uoslės nervas]] [[nl:Nervus olfactorius]] [[ja:嗅神経]] [[no:Nervus olfactorius]] [[pl:Nerw węchowy]] [[pt:Nervo olfatório]] [[fi:Hajuhermo]] [[th:เส้นประสาทรับกลิ่น]] [[zh:嗅神經]]