Olfactory nerve
| Nerve: Olfactory nerve
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| Latin
| nervus olfactorius
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| Gray's
| subject #196
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| MeSH
| Olfactory+Nerve
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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 nerve consists of a collection of sensory nerve fibers that extend from the olfactory epithelium to the olfactory bulb, passing through the many openings of the cribriform plate, 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 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 to see if the patient can detect the smell is then repeated on the other nostril.
Additional images
See also
- Anterior olfactory nucleus
| Nerves of head and neck: the cranial nerves |
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| I-IV | olfactory • optic • oculomotor (superior branch, inferior branch) • trochlear |
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| V: trigeminal | trigeminal ganglion • ophthalmic • maxillary • mandibular |
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| VI: abducens | no significant branches |
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| VII: facial | nervus intermedius • geniculate • inside facial canal (greater petrosal, nerve to the stapedius, chorda tympani) • at exit from stylomastoid foramen (posterior auricular, digastric • stylohyoid) • on face (temporal, zygomatic, buccal, mandibular, cervical) |
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| VIII: vestibulocochlear | cochlear (striae medullares, lateral lemniscus) • vestibular (Scarpa's ganglion) |
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| IX: glossopharyngeal | nucleus ambiguus • ganglia (superior, petrous) • tympanic (tympanic plexus, lesser petrosal) • carotid sinus • pharyngeal branches • pharyngeal plexus |
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| X: vagus | ganglia (jugular, nodose) • in the jugular fossa (meningeal branch, auricular branch) • in the neck (pharyngeal branch, superior laryngeal ext and int, recurrent laryngeal, superior cervical cardiac) • in the thorax (inferior cardiac, pulmonary branches, anterior vagal trunk, posterior vagal trunk) • in the abdomen (celiac branches - renal branches - hepatic branches of anterior vagal trunk - anterior gastric branches of anterior vagal trunk - posterior gastric branches of posterior vagal trunk) |
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| XI-XII | accessory • hypoglossal |
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