Parotid gland: pyra­mids, chip­munks, shark teeth

The Weekend Australian - Travel - - Health - Dr Adam Taor

What is it? The largest of our sali­vary glands, which make saliva (aka spit). There is one on each side of our face, and they are shaped like an up­side-down pyra­mid, sit­ting not far un­der the skin in front of and be­low our ear. What does spit do? Spit is a multi-tasker. It helps makes food moist, so we can chew and swal­low it — any­one who has tried to eat dry crack­ers quickly will ap­pre­ci­ate the value of wet food. Spit also helps us digest food, helps clean our mouth, and kills germs. Why the name? It’s named af­ter its lo­ca­tion: parotid is from the Greek words para , mean­ing be­side, and otos , which means of the ear. How can it make you look like a chip­munk? Swelling of the gland, most com­monly caused by the in­fec­tious dis­ease mumps, dis­torts our face and is called ‘‘ chip­munk face’’. What’s it got to do with shark teeth? Spit reaches our mouth from the gland via a tube called Stensen’s duct. Niels Stensen, a 17th-cen­tury Dan­ish anatomist, dis­cov­ered it while dis­sect­ing an­i­mal heads — a favourite party piece of his. Stensen was also a ge­ol­o­gist, and he was one of the first to re­alise that fos­sils came from liv­ing things. He’d dis­sected a shark’s head given to him by the Grand Duke of Tus­cany, and saw that the teeth re­sem­bled strange ob­jects found in rock called tongue stones. Th­ese were be­lieved to be ser­pent tongues turned to stone by Saint Paul. Stensen cor­rectly sug­gested they were orig­i­nally shark’s teeth.

Il­lus­tra­tion: Nathalie Gar­cia

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