A significant anatomical finding emerged in 2020 with the identification of a previously unrecognized pair of macroscopic salivary glands. This discovery highlights that despite centuries of anatomical study, there are still structures within the human body that remain largely uncharacterized.
Discovery of the Tubarial Glands
The tubarial glands were discovered in 2020 by a team of Dutch researchers at the Netherlands Cancer Institute. This finding occurred incidentally during prostate cancer research, utilizing advanced imaging technology known as prostate-specific membrane antigen (PSMA) PET/CT scans. These scans, which combine positron emission tomography (PET) with computed tomography (CT), allowed for highly sensitive and specific visualization of salivary gland tissue due to PSMA uptake.
The glands had been overlooked for so long primarily due to their deep and somewhat inaccessible location within the head. Traditional imaging methods, such as standard CT scans or MRI, often rendered these glands as shadowy or indistinct regions of soft tissue, making their identification challenging. The superior sensitivity of PSMA PET/CT enabled researchers to distinguish these structures from surrounding tissues and confirm their glandular nature.
Location and Structure
The tubarial glands are a pair of salivary glands situated in the nasopharynx, the upper part of the throat located behind the nose and above the soft palate. Specifically, they are found near the torus tubarius, an elevation surrounding the opening of the Eustachian tube. These glands extend from the skull base down along the inner side of the superior constrictor muscle, positioned on the dorsolateral wall of the nasopharynx.
Structurally, the tubarial glands are diffuse, branched tubular glands, differing from the more compact and well-defined major salivary glands like the parotid or submandibular glands. Histological analysis indicates they are predominantly composed of mucinous acini, which are secretory units producing a thick, mucous. The average length of these glands is approximately 3.8 to 3.9 centimeters (about 1.5 inches).
Function of the Tubarial Glands
As salivary glands, the primary role of the tubarial glands is the production and secretion of saliva. This saliva lubricates the upper aerodigestive tract, specifically the nasopharynx and oropharynx. The mucinous fluid they release helps coat and moisten the mucosal surfaces of the pharynx.
The lubrication provided by these glands contributes to various physiological processes, including aiding in swallowing and speech. Their secretions also assist in protecting the upper aerodigestive tract. Given their size and location, they are considered a significant source of secretion for mucosal protection in the pharyngeal region.
Clinical Implications
The discovery of the tubarial glands holds implications, particularly in head and neck cancer treatment. Radiation therapy for cancers in this region frequently causes damage to salivary glands, leading to severe side effects. If not accounted for, the tubarial glands can be inadvertently exposed to radiation, contributing to debilitating conditions such as xerostomia (dry mouth) and dysphagia (difficulty swallowing).
Xerostomia and dysphagia can reduce a patient’s quality of life, impacting their ability to eat, speak, and maintain oral health. Historically, while major salivary glands were considered during radiation planning, these newly identified glands were not, potentially explaining persistent side effects in some patients. Mapping and protecting the tubarial glands during radiation planning, by utilizing advanced imaging like PSMA PET/CT to delineate their precise location, can help mitigate these adverse effects. Ongoing research is focused on further understanding their clinical impact and developing strategies to shield them during radiation therapy.