😤 Olfactory receptors 1️⃣ are the most important cells of the olfactory epithelium and they are the first order neurons of the cranial nerve I
😤There are approximately 100 million such receptors in the olfactory epithelium found along the roof of the nasal cavity including the superior and upper middle conchae
😤Olfactory receptors project through the cribriform plate in the ethmoid bone
😤They have multiple cilia immersed in a surrounding matrix of mucus and a long dendrite
😤Odiferous chemicals get dissolved in this mucus and then trigger the olfactory receptors
😤The impulses pass through the neuron to the olfactory bulb (lies in base of frontal cortex in anterior fossa), which has projections to cortical areas
😤The primary olfactory area in the temporal lobe process such informations through it’s connections with the hypothalamus, thalamus and frontal cortex
😤The other major cell type is basal cells 2️⃣ found deep to the olfactory neurons (olfactory neurons have a half-life of one month) and replace them, as they mature
😤3️⃣Sustentacular or supporting cells constitute the columnar mucus epithelium found between the receptors
😤There are 4️⃣Olfactory (Bowman’s) glands found in the connective tissue beneath the olfactory epithelium which produce the mucus in which the odiferous chemicals dissolve
❓➡️ 🅰️ Finally answer to the question
😤The innervation of the olfactory epithelial cells from cranial nerve VII (facial nerve) explains the tears and sniffing evoked by some smells.
Reference: Tortora GJ, Grabowski SR. Principles of Anatomy and Physiology, 8th edn. New York, NY: HarperCollins, 1996; pp. 454–5
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