Olfactory Nerve: Difference between revisions
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== Structure == | == Structure == | ||
* The olfactory nerve, or cranial nerve I, is unique among cranial nerves. | |||
* It's composed of sensory nerves for smell. | |||
* | == Origin == | ||
* Originates in the olfactory epithelium in the upper part of the nasal cavity. | |||
== Pathway == | |||
* Axons pass through the cribriform plate of the ethmoid bone. | |||
* They end in the olfactory bulb on the inferior surface of the frontal lobe. | |||
== Segments of the Olfactory Nerve == | |||
<table> | |||
<thead> | |||
<tr> | |||
<th>Segment Name</th> | |||
<th>Path</th> | |||
<th>Involved Cisterns</th> | |||
<th>Length (Approx.)</th> | |||
<th>Blood Supply</th> | |||
</tr> | |||
</thead> | |||
<tbody> | |||
<tr> | |||
<td>Olfactory Receptor Neurons</td> | |||
<td>Located in the olfactory epithelium of the nasal cavity.</td> | |||
<td>Not applicable, as this segment is extracranial.</td> | |||
<td>Variable, depends on nasal cavity size.</td> | |||
<td>Branches of the anterior ethmoidal artery, a branch of the ophthalmic artery.</td> | |||
</tr> | |||
<tr> | |||
<td>Olfactory Filaments</td> | |||
<td>Pass through the cribriform plate of the ethmoid bone.</td> | |||
<td>Not directly associated with any specific cistern but traverse from nasal cavity to cranial cavity.</td> | |||
<td>Around 2 cm (varies).</td> | |||
<td>Supplied by small branches from the anterior ethmoidal artery.</td> | |||
</tr> | |||
<tr> | |||
<td>Olfactory Bulb</td> | |||
<td>Situated on the inferior surface of the frontal lobe, immediately above the cribriform plate.</td> | |||
<td>Lies within the anterior cranial fossa, no specific cistern involved.</td> | |||
<td>Approximately 1-1.5 cm in length.</td> | |||
<td>Anterior cerebral artery (ACA), specifically the fronto-orbital branch.<br>Anterior ethmoidal artery also contributes.</td> | |||
</tr> | |||
<tr> | |||
<td>Olfactory Tract</td> | |||
<td>Extends posteriorly from the olfactory bulb.</td> | |||
<td>Located in the subarachnoid space, no specific cistern involved.</td> | |||
<td>About 2-3 cm in length.</td> | |||
<td>Primarily supplied by the anterior cerebral artery, particularly its orbital frontal branches.</td> | |||
</tr> | |||
</tbody> | |||
</table> | |||
== Olfactory Bulb == | |||
* The olfactory bulb is part of the brain where the olfactory nerves begin. | |||
* It processes odor information and sends it to the brain. | |||
== Intracranial Course == | |||
* From the olfactory bulb, the olfactory tract extends posteriorly. | |||
* The tract divides into medial and lateral striae. | |||
== Central Connections == | |||
* The medial striae connect to the contralateral olfactory area. | |||
* The lateral striae project to the ipsilateral primary olfactory cortex. | |||
== Clinical Significance == | |||
* Anosmia, loss of smell, can occur with damage to the olfactory nerves. | |||
* Important in assessing frontal lobe lesions and skull base fractures. | |||
[[Category:Neuroanatomy]] | [[Category:Neuroanatomy]] | ||
[[Category:Cranial nerves]] | [[Category:Cranial nerves]] | ||
Revision as of 03:19, 25 November 2023
Structure
- The olfactory nerve, or cranial nerve I, is unique among cranial nerves.
- It's composed of sensory nerves for smell.
Origin
- Originates in the olfactory epithelium in the upper part of the nasal cavity.
Pathway
- Axons pass through the cribriform plate of the ethmoid bone.
- They end in the olfactory bulb on the inferior surface of the frontal lobe.
Segments of the Olfactory Nerve
<thead> </thead> <tbody> </tbody>| Segment Name | Path | Involved Cisterns | Length (Approx.) | Blood Supply |
|---|---|---|---|---|
| Olfactory Receptor Neurons | Located in the olfactory epithelium of the nasal cavity. | Not applicable, as this segment is extracranial. | Variable, depends on nasal cavity size. | Branches of the anterior ethmoidal artery, a branch of the ophthalmic artery. |
| Olfactory Filaments | Pass through the cribriform plate of the ethmoid bone. | Not directly associated with any specific cistern but traverse from nasal cavity to cranial cavity. | Around 2 cm (varies). | Supplied by small branches from the anterior ethmoidal artery. |
| Olfactory Bulb | Situated on the inferior surface of the frontal lobe, immediately above the cribriform plate. | Lies within the anterior cranial fossa, no specific cistern involved. | Approximately 1-1.5 cm in length. | Anterior cerebral artery (ACA), specifically the fronto-orbital branch. Anterior ethmoidal artery also contributes. |
| Olfactory Tract | Extends posteriorly from the olfactory bulb. | Located in the subarachnoid space, no specific cistern involved. | About 2-3 cm in length. | Primarily supplied by the anterior cerebral artery, particularly its orbital frontal branches. |
Olfactory Bulb
- The olfactory bulb is part of the brain where the olfactory nerves begin.
- It processes odor information and sends it to the brain.
Intracranial Course
- From the olfactory bulb, the olfactory tract extends posteriorly.
- The tract divides into medial and lateral striae.
Central Connections
- The medial striae connect to the contralateral olfactory area.
- The lateral striae project to the ipsilateral primary olfactory cortex.
Clinical Significance
- Anosmia, loss of smell, can occur with damage to the olfactory nerves.
- Important in assessing frontal lobe lesions and skull base fractures.