Olfactory nerve

The olfactory nerve is a bundle of axons from olfactory sensory neurons that passes through the cribriform plate to the olfactory bulb. It carries smell signals into the brain.

Olfactory sensory neuron: A bipolar neuron in the nasal epithelium whose cilia detect odorants and whose axon projects to the olfactory bulb. These neurons supply the axons bundled together as the olfactory nerve.
Cranial nerve: A nerve that connects the brain or brainstem with structures of the head, neck, or trunk. The olfactory nerve is cranial nerve I, with a distinctive route and organization.
Trigeminal nerve: The fifth cranial nerve, carrying facial sensation and motor fibers to muscles of mastication. It detects nasal irritation and chemical pungency, unlike the olfactory nerve’s odor signaling.
Anosmia: The complete loss of the sense of smell. Damage to olfactory axons can interrupt smell transmission and cause this deficit.
Olfactory epithelium: A specialized region of the nasal lining containing olfactory sensory neurons, supporting cells, and basal cells. It houses the neurons whose axons form this nerve.
Axon: The long neuronal projection that conducts electrical signals away from a cell body. The nerve consists principally of axons extending from olfactory sensory neurons.
Optic nerve: The bundle of retinal ganglion-cell axons carrying visual information to the brain. Both are sensory cranial nerves, but the optic nerve is a continuous tract rather than multiple fascicles crossing a perforated plate.
Hyposmia: A reduced ability to detect or identify odors. Partial injury or dysfunction along the nerve can diminish olfactory sensitivity.
Cribriform plate: A perforated part of the ethmoid bone separating the nasal cavity from the anterior cranial fossa. Olfactory nerve fascicles pass through its small openings to reach the bulb.
Fascicle: A bundle of nerve fibers enclosed together by connective tissue. Small groups of olfactory axons pass through individual openings in the cribriform plate.

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