The bone through which the olfactory (smell) fibers of the brain perforate is the ethmoid. Being riddled by many separate nerve branches, it is often called a sieve. Forming the floor beneath the forward brain near midline it is flattish on top. But as the roof of the nasal recess, it has all sorts of curvy hang down thingies sometimes described as corn flake shaped.

An abrupt heave ho of the skull can shear off the thin nerves that directly penetrate the ethmoid. Sense of smell is then lost. Also, if fractured, cerebrospinal fluid can leak out giving a 'runny nose' that might not get the right interpretation. Bleeding tracks forward in such a manner that the eyes go black & blue to both sides of the bridge of the nose at once - racoon eyes.