[Intracisternal length of the brain path and nerve tracts of the I to IV cranial nerves].

The olfactory bulb has a length of 12.27 mm whereas the length of the olfactory tract from the beginning to where it crosses the optic nerve is 21.2 mm (mean). The intracranial portion of the optic nerve is 10.3 mm long. From the brain stem to its dural exit the III nerve measures 18.82 mm, and the IV nerve 32.65 mm. The range of variation in the lengths of the nerves, as well as their immediate relations are included in the investigation.