For the past three centuries, doctors have been under the impression that humans have three major types of salivary glands, found near the ears, below the jaw, and under the tongue. "Now, we think there is a fourth," Dr. Matthijs Valstar of the Netherlands Cancer Institute tells the New York Times. The Dutch researchers were looking for tumorous growth using a new kind of advanced scan of tissues when they spotted thin, flat glands, each about two inches long, on the tubes joining the ears and throat and hidden under the base of the skull. "We thought it wasn't possible to discover this in 2020," Valstar tells CNN, which notes the glands can't be seen on MRI or CT scans. But they did indeed find the glands—similar to the salivary glands found under the tongue and ones they propose naming tubarial glands—in PSMA PET/CT scans of 100 people (all but one male) and in two cadavers, male and female.
"These findings support the identification of the tubarial glands as a new anatomical and functional entity," reads the study published last month in Radiotherapy and Oncology. The researchers—who hope to see their findings replicated in a larger, more diverse set of patients—acknowledge there will be debate over whether the glands are a new organ or part of a system of 1,000 minor salivary glands found across the lining of the mouth and throat, per the Times. Either way, they believe knowledge of the glands could help patients with head and neck cancer who undergo radiation therapy. In administering radiation, doctors take care not to damage delicate salivary glands—which prove key in tasting, speaking, and swallowing. The researchers speculate that patients who end up with chronic dry mouth and swallowing problems may have suffered damage to these glands. (Read more human body stories.)