Over thousands of years of study of the human body through dissection and, more recently, modern-day imaging techniques, scientists have observed and analyzed various glands—that is, structures or organs that produce and secrete a substance or substances essential for proper physiological functioning. Remarkably, a previously unknown pair of salivary glands—termed tubarial salivary glands—has been discovered in the human nasopharynx region. This region is the space between the posterior nasal openings, above a horizontal plane through the lower margin of the palate. Physicians made the discovery during routine positron emission tomography (PET) and computed tomography (CT) scans with prostate-specific membrane antigen (PSMA) ligands performed on a male patient with prostate cancer. Subsequent imaging studies carried out on another 99 male patients, 1 female patient, and 2 cadavers (1 male and 1 female) confirmed the presence of tubarial glands. Thus, tubarial glands are considered to be a newly identified anatomical component of the salivary gland system in humans. See also: Computerized tomography; Gland; Ligand; Medical imaging; Pharynx
Located behind the nose in the upper part of the throat, tubarial salivary glands measure approximately 3.9 cm (1.5 in.) in length. The presence of these macroscopic glands suggests that their purpose is to moisten and lubricate areas of the upper throat, including the nasopharynx and oropharynx (located between the lower border of the soft palate and the larynx). Tubarial glands therefore complement the three other major sets of large salivary glands presently known in humans: (1) the sublingual glands underneath the tongue, (2) the submandibular glands below the jaw, and (3) the parotid glands toward the back of the jaw. In addition, approximately 1000 microscopic salivary glands are thought to be dispersed throughout the mucosal tissue of the mouth and throat. See also: Oral glands
Tubarial salivary glands are named as such because of their location over a piece of cartilage called the torus tubarius, which is a mucosal elevation in the nasopharynx. The failure of investigators to previously notice the presence of tubarial glands or to correctly understand the function of these structures (if they had been noticed) can possibly be attributed to their poorly accessible anatomical location under the skull base. Typically, nasal endoscopy is the only method to observe this area, and previous researchers who may have observed the flat glandular structures or duct openings of the tubarial glands likely did not interpret these structures as parts of a larger salivary gland.
The identification of tubarial glands has repercussions for patients requiring radiation treatments for various illnesses, particularly cancer. Typically, radiologists and oncologists avoid irradiation of salivary glands during radiation treatment regimens. If subject to radiation, salivary glands could be damaged, reducing or eliminating their function and often causing negative side effects (for example, dysfunctional eating, swallowing, or speaking). Up to now, radiation specialists have not specifically avoided irradiation of the nasopharynx region where tubarial glands are located. However, radiation therapists must now be aware of the tubarial glands' vulnerability to radiotherapy. See also: Cancer; Oncology; Radiation biology; Radiation injury to plants and animals; Radiation therapy