Where do the cells project through the ethmoid bone and synapse with the olfactory bulbs?

The afferent nerve fibres of the olfactory receptor neurons transmit nerve signal about odours to the CNS. From the olfactory mucosa (inside the nasal cavity), the nerve travels up through the cribriform plate of the ethmoid bone where the fascicles enter the olfactory bulb. The olfactory bulb is a structure which contains specialised neurones, called mitral cells and the nerve fibres synapse with those mitral cells, forming collections known as synaptic glomeruli. From the glomeruli, second order nerves then pass into the olfactory tract which runs to the CNS (primary olfactory cortex).