Cribriform Plate: a light and spongy bone. It consists of a horizontal plate, a perpendicular plate, and two lateral (walls). (MeSH) A very thin and fragile bone. Riddled with thousands of tiny holes through which the “axons” of olfactory “neurons” pass through to get into the brain. When there is a violent blow to the front of the head, it knocks the cribriform plate out of alignment, casing the delicate olfactory axons that run through it to be sheared off. With the axons cut off, the olfactory nerve is dead and the sense of smell is destroyed. (Herz, 6) Also referred to as ‘ethmoid bone.’

Nasal Cavity: the portion of the “respiratory” passages on either side of the ‘nasal septum.’ Nasal cavities are lined with nasal “mucosa.” (MeSH) Contains olfactory cells and is divided into two chambers. (OxfordMed) Also referred to as the ‘internal nose.’

Nose: the organ of olfaction. The external nose is composed of “cartilage” and covered with skin. It leads to the nasal cavity. (OxfordMed) The function of the nose is to filter, warm, and humidify the air that we breathe. The interior of the nose is not a smooth cavity but possesses a complex geometry of ridges shaped by the underlying bones. The air convection system it generates is more complex than the airflow around an aircraft wing. (Herz, 20)

Olfactory Bulbs: blueberry-shaped and -sized extensions of the brain, one for each nostril (Herz, 6) Anatomical structures located in the “forebrain” that receive neural input regarding odors that have been detected by cells within the nasal cavity. The axons of olfactory receptor cells extend into the olfactory bulb. (NCIt) Small bilateral “cortical” outgrowths which communicate with the primary olfactory cortices in the “temporal lobes.” Involved in bidirectional communication with the brain and olfactory nerves. A common misconception is that they are themselves, the peripheral "olfactory nerves." (Fisch, 382)

Olfactory Cortex: responsible for processing smells directed from receptors in the nose. A bundle of neurons extends from the olfactory cortex down to the “thalamus.”  (Koch, 124) Odor "sensation" happens at the level of our nose and olfactory bulb, but olfactory "perception" occurs in our mind, where our personal experiences with scents take over. (Herz, 29)

Olfactory Epithelium: underlying connective tissue which includes receptor cells and supporting cells. (Patestas, 337) Two patches of yellowish mucus membrane about seven centimeters up from each nostril. (Herz, 320)

Olfactory Nerve: tiny “filaments” in the nasal walls. (Fisch, 382) Collectively all the olfactory axon bundles. (Patestas, 338) The 1st “cranial nerve.” The olfactory nerve conveys the sense of smell. It is formed by the axons of olfactory receptor neurons which project from the olfactory epithelium to the olfactory bulb. (MeSH)

Olfactory Receptors: (receptors for chemicals) located on the tips of the olfactory neuron dendrites. We have approximately 20 million olfactory receptors covering the (olfactory) epithelium of both our right and left nostrils. However, they would look paltry to a dog, like the bloodhound, who has about 220 million olfactory receptors. (Hertz, 20) Projecting from them are fiber-like olfactory hairs. When stimulated, they communicate neural messages to the olfactory bulb. Their direct connection to areas of the “cerebral cortex” and “limbic system” is unique to our sense of smell. All other bodily sensations are first processed in the “thalamus” before being relayed to the higher brain centers in the cortex. They are the only neurons that directly link the brain and the outside world. (Hockenbury, 101) The constant chemical interaction (between odor chemicals and olfactory receptors) appears to be tough on the receptors… which are constantly being replaced. The life of a olfactory receptor is about 60 days. (Kolb, 398) Estimates suggest that (these) odor receptors in the soft tissue high inside the nose are sensitive to 10,000 or more different odors. (Mathews, 50) Also referred to as ‘chemoreceptors.’