Smell. Smell, scientifically termed olfaction, begins posteriorly (the rear) in the nasal cavity, where millions of sensory neurons termed olfactory receptors, are embedded in a specialized strip of tissue covered in yellow mucosa called the olfactory epithelium. The tips of these cells contain proteins, which bind to the ligands, or odor molecules that enter the nose. Many different odor molecules can activate each receptor, and each odor molecule can activate several different types of receptors. After the smell binds to the receptors, their axons enter small nerve bundles (collectively termed the 1st cranial nerve ), which pass through the perforations in the cribriform plate of the ethmoid bone, by synapsing onto the mitral cells, thus promptly entering the olfactory bulb. These mitral cells then fire action potentials into the olfactory cortex and the information then makes its way to the various sensory, motor, autonomic connections with the limbic system including the hippocampus, the amygdala, the septal area, and so on.