Top: Cranial Nerve I (Olfactory Nerve) Branches in the Nasal Cavity
Bottom: Base of Brain - Olfactory Nerve and Optic Chiasma Emphasized
Ever wonder why you don’t think of an event or memory for years at a time, but the unexpected whiff of a familiar smell can bring it all flooding back?
The olfactory (smell-processing) nerve is the first (I) of the cranial nerves, and is, like the other cranial nerves, directly connected to the brain. However, unlike the others, the cortex of the brain where scent is processed is not near the back of the brain. It is between the frontal and temporal lobe, very close to the long-term memory centers, and the optic nerve passes directly below the optic nerve. As such, smells can often trigger strong visual and emotional memories that had a unique scent involved, even if you didn’t notice the scent at the time.
Despite the human’s relatively weak and somewhat-insignificant sense of smell, it’s still considered the sense most closely associated with all episodic (event) long-term memories. Certain smells have been known to bring back memories more than half a century after the event occurred.
Anatomy, Descriptive and Surgical. Henry Gray, 1911.