Olfactory Pathway Essay

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The olfactory receptors are embedded in a specialized patch of yellow-tinted mucous membrane in the roof of the nasal cavity. These receptors are bipolar neurons covered with modified, non-motile cilia. These cilia probably contain the active sites for the olfactory transduction process. Axons from the olfactory receptors enter small nerve bundles (collectively termed the 1st cranial nerve) which pass through the perforations in the cribiform plate of the ethmoid bone and promptly enter the olfactory bulb. The olfactory bulbs lie on the ventral aspect of the frontal lobes. The olfactory bulbs and all other parts of the olfactory pathways are telencephalic derivatives. Within the olfactory bulbs the olfactory nerves synapse on mitral cells whose axons project directly to the olfactory cortex. The olfactory tract connects the olfactory bulb with the cerebral hemispheres. Axons of mitral cells pass directly back to the olfactory cortex on the ipsilateral side. Anterior commissure is a small commissure that connects the two halves of the olfactory system. Olfactory cortex is the portions of the cerebral cortex that receive direct projections from the olfactory bulb (via mitral cell axons) are collectively referred to as the olfactory cortex. It is located on the base of the frontal lobe and medial aspect of the temporal lobe. On the base of the frontal lobe it overlies the anterior perforated substance through which the striate arteries enter the interior of the brain. On the temporal lobe the olfactory cortex covers the rostral portion of the parahippocampal gyrus including a medial bulge known as the uncus or uncinate gyrus. From the olfactory cortex, olfactory information is relayed via the mediodorsal nucleus of the thalamus to the insular and orbitofrontal cortex. The insular cortex, which is buried in the depths of the Sylvian fissure, also

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