The olfactory nerve is the first of twelve cranial nerves. It consists of a collection of sensory nerve fibers that extend down from the olfactory bulb and pass through the many openings of the cribriform plate, a sieve-like structure. The specialized olfactory receptor neurons of the olfactory nerve are located in the olfactory mucosa of the upper parts of the nasal cavity.

The sense of smell (olfaction) arises from the stimulation of the olfactory receptors by activation from gas molecules that pass by the nose during respiration. The resulting electrical activity is transduced into the olfactory bulb which then transmits the electrical activity to other parts of the olfactory system and the rest of the central nervous system via the olfactory tract.

The olfactory nerve is the shortest of all the twelve cranial nerves and only one of two cranial nerves (the other being the optic nerve) that do not join with the brainstem.