What is the primary function of the olfactory nerve?

The olfactory nerve (CN I) is a purely sensory nerve responsible for the special sense of smell. It transmits olfactory signals from the nasal cavity to the brain.

What makes the olfactory nerve unique compared to other cranial nerves?

It has two key unique features: its primary sensory neurons are located in the olfactory epithelium on the body surface of the nasal cavity, and these neurons undergo continuous regeneration from stem cells, which is unusual among neurons.

How does the olfactory nerve transmit signals from the nose to the brain?

The nerve consists of small bundles of non-myelinated fibres that arise from receptor neurons in the olfactory epithelium. They pass through the cribriform plate of the ethmoid bone to enter the anterior cranial fossa and synapse in the olfactory bulb.

What is anosmia, and what can cause it in relation to the olfactory nerve?

Anosmia is the loss of the sense of smell. It can be caused by conditions like atrophic rhinitis or fractures of the anterior cranial fossa (e.g., ethmoid fractures), which may damage the nerve or its pathway.

How is the olfactory nerve tested clinically?

Testing involves asking the patient to identify familiar odors (e.g., peppermint or garlic) with one nostril occluded at a time and eyes closed to assess smell function.

What is the functional component of the olfactory nerve?

It contains Special Somatic Afferent (SSA) fibres that carry the sense of smell from the olfactory region of the nasal cavity to the olfactory bulb.

Olfactory Nerve (CN I) – Smell Pathway & Anatomy