Final answer:
Olfactory fibers directly enter the olfactory bulbs when passing through the roof of the nose. The olfactory bulbs are part of the olfactory system responsible for the sense of smell.
Step-by-step explanation:
When olfactory fibers pass through the roof of the nose, they directly enter the olfactory bulbs. The olfactory bulbs are part of the olfactory system, which is responsible for the sense of smell. Olfactory signals from the bulbs travel to various parts of the brain, such as the primary olfactory cortex in the temporal lobe, the limbic system, and the hypothalamus, where smells become associated with long-term memory and emotional responses.