The
olfactory nerve is typically considered the first
cranial nerve, or simply
CN I. It contains the
afferent nerve fibers of the
olfactory receptor neurons, transmitting
nerve impulses about
odors to the
central nervous system, where they are
perceived by the sense of smell (
olfaction). Derived from the
embryonic nasal placode, the olfactory nerve is somewhat unique among cranial nerves because it is capable of some regeneration if damaged. The olfactory nerve is sensory in nature and originates on the
olfactory mucosa in the upper part of the
nasal cavity. From the olfactory mucosa, the nerve (actually many small nerve fascicles) travels up through the
cribriform plate of the
ethmoid bone to reach the surface of the brain. Here the fascicles enter the olfactory bulb and synapse there; from the bulbs (one on each side) the olfactory information is transmitted into the brain via the olfactory tract. The fascicles of the olfactory nerve are not visible on a cadaver brain because they are severed upon removal.