Cribriform plates

The left and right cribriform plates of the ethmoid bone are separated by the crista galli of the ethmoid, and are surrounded by the perpendicular plate of the frontal bone.  The cribriform plates and thin and riddled with small holes that allow bundles of olfactory nervelets to pass from the olfactory epithelium of the upper nasal turbinate to the olfactory bulb.  

Saggital section through the nasal cavity shows the olfactory nervelets traveling through the holes in the cribriform plate, allowing them to communicate with the olfactory bulb.