Olfactory Nerve: Difference between revisions
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== Structure == | == Structure == | ||
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* The olfactory nerve, or cranial nerve I, is unique among cranial nerves. | * The olfactory nerve, or cranial nerve I, is unique among cranial nerves. | ||
Revision as of 03:18, 13 January 2024
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
| 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. |
|
| 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.