Science Alert: Medical researchers have made a surprise anatomical discovery, finding what looks to be a mysterious set of salivary glands hidden inside the human head – which somehow have been missed by scientists for centuries up until now.
 This “unknown entity” was identified by accident by doctors in the Netherlands, who were examining prostate cancer patients with an advanced type of scan called PSMA PET/CT. When paired with injections of radioactive glucose, this diagnostic tool highlights tumours in the body.
 In this case, however, it showed up something else entirely, nestled in the rear of the nasopharynx, and quite the long-time lurker.”People have three sets of large salivary glands, but not there,” explains radiation oncologist Wouter Vogel from the Netherlands Cancer Institute. “As far as we knew, the only salivary or mucous glands in the nasopharynx are microscopically small, and up to 1,000 are evenly spread out throughout the mucosa. So, imagine our surprise when we found these.”
 Salivary glands are what produce the saliva essential for our digestive system to function, with the bulk of the fluid produced by the three major salivary glands, known as the parotid, submandibular, and sublingual glands.
There are approximately 1,000 minor salivary glands too, situated throughout the oral cavity and the aerodigestive tract, but these are generally too small to be seen without a microscope.
The new discovery made by Vogel’s team is much larger, showing what appears to be a previously overlooked pair of glands – ostensibly the fourth set of major salivary glands – located behind the nose and above the palate, close to the centre of the human head.