The Biology of the Tubarial Salivary Glands: A New Discovery

For centuries, it was believed that the human body held few anatomical secrets. We were taught that there are three pairs of major salivary glands (parotid, submandibular, and sublingual) and thousands of minor glands scattered throughout the mouth.

However, in late 2020, researchers at the Netherlands Cancer Institute made a startling discovery while examining PET/CT scans: a fourth pair of major salivary glands hidden deep in the nasopharynx. These are the Tubarial Salivary Glands.

The Discovery: PET-CT and PSMA

The discovery occurred almost by accident. While using a new type of scan called PSMA PET/CT (typically used to detect prostate cancer), researchers noticed two large, symmetrical "hot spots" at the back of the nasal cavity, near the torus tubarius (the entrance to the Eustachian tubes).

These structures were roughly 1.5 inches (4 cm) long. Initially, it was thought they might be minor glands, but their size and consistency across 100 different patients confirmed they were a distinct, macroscopic pair of salivary glands.

The Biological Function: Lubricating the 'Internal Ear'

The Tubarial glands are located at the crossroads of the nose and the throat. Their primary function appears to be the Lubrication and Protection of the Nasopharynx.

The Saliva: These glands produce a seromucous secretion that keeps the back of the throat and the entrance to the Eustachian tubes moist.
Physiological Importance: This lubrication is essential for smooth swallowing, clear speech, and the pressure-regulation functions of the middle ear.

Impact on Cancer Treatment

The primary reason this discovery is significant is for Radiation Oncology. When patients undergo radiation for head and neck cancers, doctors try to avoid the known salivary glands to prevent "Xerostomia" (chronic dry mouth). Because the Tubarial glands were unknown, they were often hit with high doses of radiation.

Research showed that the more radiation these hidden glands received, the more patients suffered from complications with swallowing and speech. By identifying their location, oncologists can now map radiation beams to avoid them, significantly improving the quality of life for cancer survivors.

Why Were They Hidden for So Long?

You might wonder how a large organ could remain hidden until the 21st century.

Deep Location: The Tubarial glands are nestled in a complex, bony area at the base of the skull, making them invisible to external examination.
Lack of Contrast: On standard MRI or CT scans, they look identical to the surrounding mucosal tissue. It was only the specific "Radio-labeling" of the PSMA scan that made them light up.

Conclusion

The discovery of the Tubarial salivary glands is a humbling reminder that biology is still full of mysteries. It proves that even in an era of high-tech imaging, there is still much to learn about our own architecture. By refining our anatomical maps, we can provide better, more precise medical care and continue to marvel at the intricate engineering of the human body.

Scientific References:

Valstar, M. H., et al. (2020). "The tubarial glands: A potential new organ at risk for radiotherapy." Radiotherapy and Oncology.
Smit, L. A., et al. (2021). "The anatomy and function of the newly discovered tubarial glands." (Follow-up study).