The =olfactory nerve= (N. olfactorius) is peculiar in that its fibers
are not aggregated to form a trunk, but are connected in small bundles
with the olfactory bulb. They are non-medullated, and are the central
processes of the olfactory cells which are situated in the olfactory
region of the mucous membrane of the nasal cavity. This region is
distinguished by its brown color and comprises most of the lateral mass
of the ethmoid, a small adjacent area of the superior turbinal, and the
corresponding surface of the septum nasi. The nerve-bundles are inclosed
in sheaths derived from the membranes of the brain and pass through the
foramina of the cribriform plate to join the convex surface of the
olfactory bulb. Some fibers come from the vomero-nasal organ of
Jacobson.