Your mouth contains three pairs of large salivary glands plus hundreds of tiny ones, spread across a surprisingly wide area from just below your ears down to the floor of your mouth and deep into your jaw. Most people picture saliva appearing vaguely “from somewhere in the cheeks,” but the glands responsible are distinct organs with specific positions, each draining saliva through its own duct to a precise spot inside your mouth. Where each gland sits matters for everything from why you get a swollen jaw when dehydrated to why radiation oncologists plan their beams so carefully around your face.
The Three Major Pairs
The major salivary glands are paired, meaning you have one on each side. Together they produce the bulk of your saliva, though each pair contributes a different type and volume.
Parotid Glands
The parotid glands are the largest. Each one sits in front of and slightly below the ear, wedged between the back edge of the jawbone and the mastoid process (that bony bump you can feel behind your earlobe). The gland wraps around the back of the jaw, and part of it extends forward over the chewing muscle you can feel tighten when you clench your teeth. If you’ve ever had mumps, the swelling on either side of your face was your parotid glands inflamed.
Each parotid drains through a single duct called Stensen’s duct, which runs forward across the cheek and opens into the mouth through a tiny hole in the inner cheek lining, roughly opposite your upper second molar. You can sometimes feel this opening with your tongue as a small bump. The saliva the parotid produces is watery and thin, rich in enzymes that start breaking down starches.
One reason the parotid’s exact anatomy matters clinically is that the facial nerve, the nerve controlling the muscles of facial expression, threads directly through the gland on its way to the face. That relationship makes parotid surgery delicate. Damage to the facial nerve during operations near the parotid is a well-known risk, and surgeons rely on careful knowledge of facial nerve landmarks to avoid it.1PubMed. Landmarks of the facial nerve: implications for parotidectomy Several lymph nodes are also embedded within the parotid itself, which is unusual among salivary glands and is one reason the parotid sometimes swells in response to infections or immune conditions that have nothing to do with saliva production.
Submandibular Glands
The submandibular glands sit tucked beneath the lower jaw, roughly where the jawbone curves from horizontal to vertical. Each one is about the size of a walnut, generally triangular or irregularly rounded in shape, with average dimensions of roughly 29 mm top to bottom, 30 mm front to back, and 15 mm side to side.2PubMed Central. Anatomical localization of submandibular gland for botulinum toxin injection If you press gently under your jawline about an inch or two forward from the angle of the jaw, you may be able to feel the gland as a soft, slightly firm lump.
Each submandibular gland drains through Wharton’s duct, which runs forward along the floor of the mouth and opens at a small papilla just beside the frenulum under your tongue. The submandibular glands produce a mixed saliva, partly watery and partly mucous, and they account for a large share of resting saliva, the kind your mouth produces when you’re not eating. Because the duct runs uphill from the gland to its opening, and because the saliva is thicker than the parotid’s output, the submandibular system is the most common site for salivary stones.3PubMed Central. Unusually large sialolith of Wharton’s duct
Sublingual Glands
The sublingual glands are the smallest of the three major pairs. Each one lies in the floor of the mouth, directly beneath the tongue and above the mylohyoid muscle. Unlike the parotid and submandibular glands, each sublingual gland has multiple small ducts rather than a single main duct, and these drain along a ridge of tissue called the sublingual fold on the floor of the mouth. A few of the smaller ducts may join Wharton’s duct instead. The sublingual glands produce mostly mucous saliva, the thick, slippery kind that helps lubricate food for swallowing.
Hundreds of Minor Glands You’ve Never Noticed
Beyond the three major pairs, your mouth is studded with somewhere between 400 and 800 minor salivary glands scattered throughout the soft tissue.4Diagnostic Histopathology. Diagnostic difficulties in lesions of the minor salivary glands These are tiny, usually just a few millimeters across, and they live in the connective tissue beneath the lining of the lips, cheeks, palate (including the soft palate and uvula), tongue, and the area behind the last molars.5PubMed. Imaging of Malignant Minor Salivary Gland Tumors of the Head and Neck You can actually see some of them if you pull your lower lip down and look at the inner surface under good light: those small bumps just beneath the mucosa are labial minor salivary glands.
Minor glands produce mostly mucous secretion, and their output is continuous. While each individual gland contributes a tiny volume, together they keep the mucosal surfaces moist between meals, when the major glands are relatively quiet. The hard palate has a particularly dense concentration of minor glands, which is one reason your palate stays moist even though it’s farther from the major gland openings.
Von Ebner’s Glands and Taste
One specialized set of minor salivary glands deserves separate mention. Von Ebner’s glands are serous (watery, not mucous) glands located beneath the circumvallate papillae, those large, round bumps arranged in a V-shape at the back of your tongue. Their ducts open into the trenches surrounding each papilla. For a long time, these glands were thought of as simple housekeepers, washing away food debris from around the taste buds.6PubMed. The anatomy and functional role of the circumvallate papilla/von Ebner gland complex
Recent research in mice suggests von Ebner’s glands may play a more active role. Their ducts harbor stem cells that appear to be responsible for replenishing taste bud cells on the posterior tongue. In mouse studies, a marker for stem cells called Lgr5 becomes concentrated within von Ebner’s gland ducts during the first week of life, right when differentiated taste buds start appearing.7bioRxiv. Lgr5+ ductal cells of von Ebner’s glands are stem cells for turnover of posterior tongue taste buds If confirmed in humans, this would reframe von Ebner’s glands from passive rinsing stations to active participants in taste bud maintenance.
How Saliva Gets Where It Needs to Go
The major glands don’t just ooze saliva passively. Secretion is driven primarily by parasympathetic nerve signals, the branch of the nervous system active during rest-and-digest states. For the submandibular and sublingual glands, the parasympathetic fibers travel via the chorda tympani nerve (a branch of the facial nerve) to the submandibular ganglion, a tiny relay station suspended near the floor of the mouth. From there, nerve fibers fan out to stimulate the gland cells. Parasympathetic signals to the submandibular gland don’t just trigger saliva flow; they also play a role in the gland’s development and regeneration over time.8PubMed Central. The Parasympathetic Root of the Submandibular Ganglion: A Review
For the parotid gland, the parasympathetic pathway is different: signals travel through the glossopharyngeal nerve to the otic ganglion (a relay near the base of the skull), and then to the gland. Interestingly, this wiring can vary between species. In rats, there is no direct connection between the glossopharyngeal nerve and the otic ganglion. Instead, the signal takes a detour through the facial nerve to reach the ganglion.9PubMed Central. The otic ganglion and its neural connections in the rat In humans the pathway is more direct, but the comparative anatomy is a reminder that salivary gland wiring is more complex than textbook diagrams sometimes suggest.
Not All Saliva Is the Same, Even Within Your Mouth
Because the glands are positioned in different locations and produce different types of saliva, the chemical composition of the fluid actually varies from one spot in your mouth to another. A recent study measuring ion concentrations at multiple intra-oral sites found that almost every ion measured showed a distinct distribution pattern. The palate, for instance, had the highest sodium concentration, while the floor of the mouth had the lowest. These patterns were consistent between individuals, suggesting they reflect the fixed positions and outputs of the glands and their ducts rather than random variation.10PubMed Central. The intra-oral variation of salivary ions
This regional chemistry has practical implications. The mineral content of saliva affects how well your teeth can remineralize after acid exposure, and it influences the pH of different zones in the mouth. Dentists have long known that tartar (calculus) tends to build up on the tongue-side surfaces of the lower front teeth and the cheek-side surfaces of the upper molars. Those happen to be the spots directly opposite the openings of Wharton’s duct and Stensen’s duct, where the most mineral-rich saliva arrives first.
The Tubarial Glands, a Surprisingly Recent Discovery
In 2020, researchers using a specialized PET scan to image prostate-cancer patients noticed a pair of previously uncharacterized glandular structures in the nasopharynx, the area behind the nose and above the soft palate. All 100 patients in the study showed these glands, each averaging about 4 cm in length. Histological analysis confirmed they were predominantly mucous salivary glands with multiple draining ducts, clustered near the torus tubarius, the ridge of tissue surrounding the opening of the eustachian tube.11PubMed. The tubarial salivary glands: A potential new organ at risk for radiotherapy The authors proposed calling them the “tubarial glands” and flagged them as a potential organ at risk during head-and-neck radiation therapy.
Whether these qualify as a genuinely “new” organ or are simply a concentrated cluster of minor salivary glands that anatomists had already noted in passing has been debated. A subsequent comprehensive analysis confirmed the glands exist as a collection of salivary tissue within the nasopharynx, proximal to the eustachian tube.12PubMed Central. A comprehensive analysis of the tubarial glands A more recent cadaver study with microscopic validation consistently identified a well-defined, lobulated glandular structure deep to the mucosa of the tubal elevation, extending variably into the oropharynx and sometimes reaching as far down as the lower border of the soft palate. The study also reported discovering a previously undescribed duct.13PubMed Central. Anatomical delineation of the tubarial gland amidst ongoing debate: Macroscopic study with microscopic validation and novel duct discovery Regardless of the naming debate, the clinical relevance is clear: these glands can be damaged by radiation aimed at nearby tumors, potentially contributing to dry mouth and swallowing difficulties that patients experience after treatment.
Where Stones and Tumors Tend to Show Up
The location of each gland and duct shapes the clinical problems that tend to arise there. Salivary stones (sialoliths) are calcium-rich deposits that block a duct, causing sudden pain and swelling during meals when the gland tries to secrete but the duct is plugged. These stones can form in any salivary duct but are most common in Wharton’s duct and the submandibular gland.3PubMed Central. Unusually large sialolith of Wharton’s duct The submandibular system’s vulnerability comes down to anatomy: its duct is long, runs against gravity, and carries thicker, more calcium-rich saliva. Parotid stones happen too but less frequently, and sublingual stones are rare.
Salivary gland tumors also follow a location pattern. A large international multicenter study found that about 68% of salivary gland tumors occurred in the major glands and 32% in minor glands. The parotid was the most common site overall, accounting for 70% of benign tumors. But for malignant tumors, the picture shifted: minor glands accounted for 47% of malignancies.14PubMed Central. Distribution and Frequency of Salivary Gland Tumours: An International Multicenter Study There’s a rough clinical rule of thumb that the smaller the gland, the more likely a tumor arising in it is malignant. So while parotid lumps are common and usually benign, a hard lump on the palate or inside the cheek deserves prompt evaluation.
Imaging the Glands
When a stone or mass is suspected, imaging helps pin down the location. Ultrasound is often the first step for the parotid and submandibular glands because they’re superficial enough to image through the skin. For duct anatomy, sialography, where contrast dye is injected into the duct opening and X-rays are taken, remains one of the best tools for mapping the fine branching of the duct system and spotting stones or narrowing. Digital subtraction sialography can show the exact location of a salivary stone and reveal duct abnormalities like strictures, which is especially useful when a procedure to scope the duct is planned.15PubMed Central. Salivary gland calculi – contemporary methods of imaging
MRI, including a non-invasive version of sialography that uses heavily T2-weighted sequences to make the fluid in the ducts glow bright without any contrast injection, has shown strong diagnostic reliability across multiple evaluators.16Journal of Medical Imaging and Radiation Sciences. The Role of Magnetic Resonance Imaging and Magnetic Resonance Sialography in the Diagnosis of Various Salivary Gland Disorders MRI is particularly helpful for soft-tissue masses and for evaluating deeper structures that ultrasound can’t reach well, including the deep lobe of the parotid gland and the sublingual space.
What Happens to Salivary Glands as You Age
Salivary glands change structurally with age. Animal studies show that aging submandibular glands develop atrophy of the saliva-producing cells along with fatty replacement and fibrosis of the supporting tissue, and the overall gland weight decreases relative to body weight.17PubMed Central. Relationship between hyposalivation and oxidative stress in aging mice Human sublingual glands show similar trends: the volume of the active secretory tissue (acini) drops by more than half with age, replaced by dramatic increases in fat and fibrous tissue.18PubMed. Quantitative age-related differences in human sublingual gland
Despite these structural changes, healthy older adults often maintain surprisingly adequate saliva production under normal conditions. The glands have substantial reserve capacity, and the remaining tissue compensates. However, when age-related glandular atrophy is combined with medications that reduce saliva flow (many common drugs for blood pressure, depression, and allergies have this side effect), the reserve can be overwhelmed, and dry mouth becomes a real problem. That’s why dry mouth is more common in older adults even though aging alone usually isn’t enough to cause it.
Protecting Salivary Glands During Radiation Therapy
For people undergoing radiation therapy for head-and-neck cancers, the location of salivary glands is a critical concern. Radiation damages the secretory cells, and the resulting dry mouth (xerostomia) can be permanent and debilitating, affecting eating, speaking, and dental health. Modern radiation planning tries to spare as much gland tissue as possible. Research guidelines indicate that severe xerostomia is usually avoided if at least one parotid gland receives a mean dose below about 20 Gy, or if both parotids are kept below roughly 25 Gy mean dose.19International Journal of Radiation Oncology, Biology, Physics. Quantitative Analyses of Parotid Gland Function After Radiotherapy in the Head-and-Neck Region: A PENTEC Review
Sparing the submandibular glands makes a large difference too. In a study of patients treated for oropharyngeal cancer, those who had at least one submandibular gland spared had markedly lower rates of significant dry mouth compared to those without sparing: at 12 months, only 6% of the spared group reported moderate-to-severe xerostomia versus 41% of the unspared group.20PubMed Central. Submandibular gland-sparing radiation therapy for locally advanced oropharyngeal squamous cell carcinoma Because the submandibular glands produce most of the resting saliva that keeps your mouth comfortable between meals, losing them hits harder than many patients expect.
Researchers have pushed this concept even further, exploring whether sparing the stem cell-rich regions within individual glands rather than the whole gland could preserve function more efficiently. A randomized trial tested whether directing lower radiation doses specifically to the main duct region of the parotid, where stem cells are concentrated, would better preserve parotid function compared to standard whole-gland sparing techniques.21PubMed. Parotid Gland Stem Cell Sparing Radiation Therapy for Patients With Head and Neck Cancer The discovery of the tubarial glands adds yet another structure that radiation planners may need to account for, though clinical guidelines on dose limits for these glands are still being developed.
How Salivary Gland Design Varies Across Mammals
If you’ve ever wondered why your dog drools so differently than you do, salivary gland anatomy offers part of the answer. Across mammals, the basic three-pair layout of major salivary glands is conserved, but the internal structure of the ducts and the secretory cells varies considerably. A broad survey of mammalian species found that the excretory ducts of salivary glands are metabolically active structures, not just passive pipes. They contain enzymes involved in transport, oxidation, and breakdown processes, and their cellular makeup differs between species in ways that don’t follow a neat evolutionary tree.22PubMed. Interlobular excretory ducts of mammalian salivary glands: structural and histochemical review
The striated ducts, another duct type found deeper within the glands, show a clearer relationship to diet. Among bats, for example, species with different diets show distinct patterns of striated duct structure and secretion, suggesting that salivary gland anatomy has adapted to dietary pressures over evolutionary time.23PubMed. Secretion by striated ducts of mammalian major salivary glands In humans, our salivary glands reflect our omnivorous diet: the parotid produces enzyme-rich watery saliva suited for starch digestion, while the submandibular and sublingual glands produce mucous-rich saliva better suited for lubricating a wide variety of food textures. The developmental blueprint for these glands is also more complex than once thought. Research has shown that salivary glands contain cells derived from all three embryonic germ layers, and some epithelial cells appear to trace their origin to neural crest cells, a finding that surprised developmental biologists.24PubMed Central. The Germinal Origin of Salivary and Lacrimal Glands and the Contributions of Neural Crest Cell-Derived Epithelium to Tissue Regeneration Understanding that cellular heritage could eventually matter for regenerative medicine, since knowing which cell lineages make up a gland is a prerequisite for trying to grow new gland tissue in the lab.