The first cranial or olfactory nerve is devoted to the special sense of smell. It is located on the base of the brain as the olfactory tract and bulb. There are about twenty olfactory nerves proper. They arise from the olfactory bulb. The olfactory tract arises from external and internal roots. The external or long root is composed of white matter. It crosses the anterior perforated space to the anterior end of the hippocampal gyrus of the temporosphenoid lobe. The inner or mesial root is also composed of white matter. It passes backward and inward to the anterior extremity of the gyrus fornicatus. Between these two diverging roots is a small triangular area of gray matter called the trigonum olfactorium. It receives a few fibers from the olfactory tract. When these fibers are noticeable, they form the middle or gray root. The tract then formed is lodged in the olfactory sulcus of the cerebrum and is surrounded at the anterior extremity by a small rounded mass of gray matter, the olfactory bulb.

Sense of Smell

Sensory

Cribriform Plate

Nasal Cavity

Nervus olfactorius

Nerve I

Nervus olfactorius [I]

Olfaktorischer Nerv

Nervio olfativo