Once olfactory receptors are stimulated, nerve impulses travel along their axons through tiny openings in the cribriform plates of the ethmoid bone. These fibers (which form the first cranial nerves) synapse with neurons located in the enlargements of the olfactory bulbs, structures that lie on either side of the crista galli of the ethmoid bone (see figs. 7.26 and 12.6).
Within the olfactory bulbs, the sensory impulses are analyzed, and as a result, additional impulses travel along the olfactory tracts to portions of the limbic system (see chapter 11, p. 422), a brain center for memory and emotions. This is why we may become nostalgic over a scent from the past. A whiff of the perfume that grandma used to wear may bring back a flood of memories. The input to the limbic system also explains why odors can alter mood so easily. For example, the scent of new-mown hay or rain on a summer's morning generally makes us feel good. The main interpreting areas for the olfactory impulses (olfactory cortex) are located deep within the temporal lobes and at the bases of the frontal lobes, anterior to the hypothalamus.
Was this article helpful?
This ebook provides an introductory explanation of the workings of the human body, with an effort to draw connections between the body systems and explain their interdependencies. A framework for the book is homeostasis and how the body maintains balance within each system. This is intended as a first introduction to physiology for a college-level course.