Anatomy of the Submandibular Gland

The submandibular glands are a pair of glands situated on the floor of the mouth below the lower jaw. They are one of the three pairs of glands that produce saliva.

While these glands usually function well, several conditions may impact them. Infections such as sialadenitis may develop due to a blockage in the glands. This can cause swelling, soreness, and loss of moisture in the mouth. Autoimmune disorders and medication side effects may also affect the submandibular glands and impede saliva production.

This article explains the structure of the glands, what they do, and how to identify and manage conditions related to the submandibular glands.

Submandibular Gland Anatomy

The submandibular glands are the second largest of the three main salivary glands—about the size of a walnut. The two other types of salivary glands are the parotid (the largest) and sublingual glands.

The submandibular glands are located in the submandibular triangle, which is underneath the mandible (lower jaw bone) and above the hyoid (tongue) bone. The mylohyoid muscle, a paired muscle that forms the floor of the mouth, separates a superficial and deep lobe in the gland. 

The submandibular duct, also called the Wharton's duct, is the excretory duct of the gland. It drains saliva from the glands at the base of the tongue. 

The blood supply to the gland comes from the facial artery and lingual artery. The parasympathetic and sympathetic nervous systems regulate the salivary glands.

Function of Submandibular Glands

The submandibular gland produces saliva, which moistens the mouth and aids in chewing, swallowing, digestion, and helps to keep the mouth and teeth clean. Unstimulated, the submandibular glands provide the majority of saliva to the mouth. On stimulation, the parotid gland takes over, producing the majority of saliva.  

The parasympathetic nervous system and the sympathetic nervous system regulate the glands. The parasympathetic system, via the facial nerve, causes the gland to produce secretions and increase blood supply to the gland.

The sympathetic nervous system is responsible for decreasing blood flow and secretions. This results in a higher concentration of enzymes in the saliva, which is essential for digesting food.

Associated Conditions

The submandibular gland usually functions without issue. But sometimes it can become blocked or affected by certain conditions.

Sialolithiasis

Tiny stones can cause the submandibular glands to become swollen, causing a condition known as sialolithiasis. Salivary stones are made of mineral deposits. Sialolithiasis most commonly affects people aged 30 to 60, and they are more common in men than in women.

Salivary gland stones can form in any of the salivary glands, but 80% of the time they occur in the submandibular glands. A definitive cause of sialolithiasis is unknown, but some factors are associated with it, including dehydration, mouth trauma, smoking, and gum disease.

Symptoms of sialolithiasis may include pain and swelling at the site of the salivary glands. These symptoms usually get worse when eating. Symptoms sometimes come and go; other times they are constant. Left untreated, the gland may become infected.

Sialadenitis

An infection in the salivary glands is called sialadenitis. Infections in the salivary glands most often affect the parotid and the submandibular glands. Older people and those with chronic health conditions are most at risk of developing a salivary gland infection.

Infections in the glands are caused by a bacteria, commonly Staphylococcus aureus. Viruses, such as mumps, can also lead to infections in the salivary glands. 

Infections are more likely to occur when there is a blockage in the gland from a stone, dehydration, or from Sjögren’s disease, an autoimmune disorder that affects the glands. Symptoms of sialadenitis may include pain and swelling around the affected gland, fever, and pus that oozes from the gland.

Sjögren’s Disease

Sjögren’s disease (formerly called Sjögren’s syndrome) is an autoimmune disorder that reduces moisture produced by the glands of the eyes and mouth. It is named after Henrik Sjögren, a Swedish eye healthcare provider who discovered the condition. 

Primary Sjögren’s disease develops on its own, and associated Sjögren’s disease in conjunction with other autoimmune diseases. While Sjögren’s disease can affect any sex, females are nine times more likely to be affected than males.

As with other autoimmune diseases, it is unknown what causes the immune system to begin attacking healthy cells. Genetics, reproductive hormones, environmental factors, and infections may be associated with the development of Sjögren’s disease.

The most common symptoms of Sjögren’s disease are dry eyes and mouth and muscle and joint pain. Additionally, you may notice an abnormal taste in the mouth, a burning sensation in the eyes, blurry vision, trouble chewing or swallowing, cough, enlarged salivary glands, tooth decay, and vaginal dryness.

Xerostomia

Xerostomia (dry mouth) occurs as a result of salivary gland hypofunction (underperformance). When the mouth is not kept adequately moist, it can cause difficulty with chewing and swallowing, and can also lead to dental decay and infections.

It may be caused by side effects from medications or chemotherapy, autoimmune disease, or infection. Symptoms include dry mouth, difficulty chewing and swallowing, sore throat, cracked lips, mouth sores, and bad breath.

Cancerous and Noncancerous Tumors

Most salivary gland tumors are benign (noncancerous). Benign tumors are most often removed via surgery. There are several different kinds of malignant tumors (cancerous tumors) of the salivary glands:

• Mucoepidermoid carcinomas are the most common cancer of the salivary glands. They most often occur in the parotid glands but can also occur in the submandibular glands.
• Adenoid cystic carcinoma often spreads along nerves, which makes it difficult to get rid of. The outlook is best for those with smaller tumors.
• Adenocarcinomas are cancers that start in the gland cells. There are many types of adenocarcinomas, including acinic cell carcinoma, polymorphous low-grade adenocarcinoma (PLGA), adenocarcinoma, not otherwise specified (NOS), and rare adenocarcinomas.
• Malignant mixed tumors are tumors of multiple tissue types. They include carcinoma ex pleomorphic adenomas, carcinosarcoma, and metastasizing mixed tumor.
• Rare salivary gland cancers include squamous cell carcinoma, epithelial-myoepithelial carcinoma, anaplastic small cell carcinoma, and undifferentiated carcinomas.

Symptoms of salivary gland tumors may include a lump or difficulty swallowing. Numbness, face pain, and drainage from the ear may also occur.

Tests

If your healthcare provider suspects a condition of the salivary glands, they may perform tests to confirm a diagnosis and offer treatment options.

Sialolithiasis

Sialolithiasis can sometimes be seen on dental X-rays. If you are experiencing pain or swelling, your healthcare provider may palpate the area. They may also order a computed tomography (CT scan) or ultrasound to rule out other conditions.

Often, at-home treatments like heat, massage, and hydration can remedy sialolithiasis. Ibuprofen may be prescribed to reduce swelling, and if an infection is suspected, your healthcare provider may also prescribe an antibiotic.

If home-treatment does not resolve the issue, an otolaryngologist may need to remove the stones. The procedure, called sialendoscopy, is done under local or general anesthesia. A small incision is made inside the mouth and a slender tube is inserted, through which small instruments are threaded to remove the stones.

Sialadenitis

Diagnosis of sialadenitis usually begins with a physical exam. CT scan and ultrasound may also be utilized.

Sialadenitis is usually treated with hydration and antibiotics. Surgical drainage may be necessary if the infection does not respond promptly. If stones are contributing to the infection, those may also be removed surgically.

Sjögren’s Disease

To test for Sjögren’s disease, your healthcare provider may order blood tests to look for antibodies in the blood. In addition to a physical exam, your healthcare provider may also order an eye exam. A biopsy of your glands may also be done. Imaging, such as sialometry and salivary scintigraphy, uses injected dye to see how your salivary glands function.

Your primary healthcare provider may coordinate your care if you have Sjögren’s disease. You may also see specialists, like rheumatologists or otolaryngologists. There is no cure for Sjögren’s disease. Instead, treatments focus on managing symptoms.

Treatments for dry eyes may include eye drops, punctal plugs, or surgery to close tear ducts. Treatments for dry mouth may include artificial saliva producers and specific dental care to prevent decay and infections.

Xerostomia

If you have a dry mouth, your healthcare provider will likely do a physical exam and tests to rule out diseases or infections. Treatment of xerostomia will first involve addressing the underlying cause, then will support the management of symptoms. Symptom management may include chewing gum and saliva substitutes. 

Salivary Gland Cancer

A test for salivary gland cancer begins with a physical exam. During the exam, your healthcare provider will examine your mouth and face. If anything looks abnormal, you may be referred to a specialist, like an otolaryngologist, for further testing.

Imaging tests, such as X-ray, CT scan, magnetic resonance imaging (MRI), positron emission tomography (PET scan), may all be used to take a closer look at the glands to see whether a tumor is present. If these tests show a tumor, the next step is usually a biopsy to determine if the tumor is benign or malignant.

Fine needle aspiration (FNA) biopsy is done when only a small amount of cells or fluid needs to be removed. During an FNA, your healthcare provider will use a local anesthetic to numb the area and insert a needle into the tumor to extract cells. The cells are then sent to a lab to be analyzed.

An incisional biopsy may be done if not enough cells were collected in an FNA. During an incisional biopsy, your healthcare provider will numb the area, then use a scalpel to remove part of the tumor. The sample is sent to a lab for evaluation. These types of biopsies are not commonly done for salivary gland tumors. 

If the lab results indicate the tumor is malignant, your healthcare provider will likely recommend surgery to remove the entire growth. Radiation and chemotherapy are also used to treat cancers of the salivary glands, especially those that have spread to other parts of the body.

Summary

Submandibular glands are one of the sections of your anatomy that you probably give little thought to...until something goes wrong. When functioning properly, these glands work with other glands to regulate saliva in your mouth.

Infections can decrease the amount of saliva produced, though, and so can the autoimmune disease Sjögren’s disease. Cancer treatments and other medications can cause another disorder, xerostomia, which also leads to dry mouth as the submandibular glands are affected.

Your healthcare provider can run diagnostic tests to pinpoint the cause and recommend treatment. In the case of Sjögren’s disease, there is no cure, but there are ways to manage dry mouth and other symptoms.