Structure:
The olfactory nerve is an extension of the midbrain
to the olfactory bulb which extends projections to sensory
receptors in the mucus membranes of the nose and mouth. In frogs, the
vomeronasal organ on the floor of the nasal cavity, samples odors in the
air breathed. When the chemicals are identified by the vomeronasal organ,
they are called vomodors. In reptiles, the tongue is flipped out of the
mouth to gather vomodors, and bring them to the vomeronasal organ for recognition,
and transfer of to the olfactory lobes for identification, and appropriate
action.
Function:
The receptors in the mucus membranes of the nose and mouth send sensations
of smell through the olfactory nerve, to the olfactory cortex of the cerebrum,
and to the thalamus. Some receptors are also on the skin. The control of
smell and respiration are linked,
so that 'bad' odors make the animal breath faster.
