Salivary Glands: Definition, Function, Innervation, Associated Disorders and Their Causes, Symptoms and Treatments

It is the tissue in the mouth that expels saliva.

Every time hot food is brought into the mouth, they are activated. The salivary glands are only found in mammals.

As exocrine glands, they expel saliva on the epithelial surface of the mouth through ducts, rather than through the bloodstream. Every day, the salivary glands produce as much as one liter of saliva.

Saliva is a mixture of water, mucus, antibacterial substance, and digestive enzymes. One of the most recognizable digestive enzymes in the human body is alpha-amylase. This enzyme is capable of breaking down starch in foods to simpler and easier to digest sugars such as glucose and maltose.

What is the function of the salivary glands?

In short, saliva itself has several functions. As the sole secretion of the salivary glands, it is useful in creating the food bolus or the finely packed ball of food that we roll inside our mouths. This shape facilitates its safe passage through the alimentary canal.

Saliva has lubricating properties that are also protective. Saliva protects the inside of the mouth, teeth, and throat as the bolus begins to be swallowed. It also cleanses the mouth after a meal and dissolves food in chemicals that we perceive as flavor.

The salivary glands come in three parts: the parotid, sublingual, and submandibular glands. Each of them is named after the area in the oral cavity in which it is found.

Parotid glands

Two parotid glands are located inside each of the cheeks. The parotid glands are the largest type of salivary gland.

They represent up to twenty percent of the saliva in the oral cavity. Its main role is to facilitate chewing, or “chewing,” and to begin the first digestive phase of food.

The parotid gland is remarkably labeled as a serous type of gland. The serous glands are those that secrete a fluid rich in proteins, which in this case is a suspension rich in alpha-amylase enzymes.

Submandibular gland

This gland is located near the jaw. This is the moving part of the jaw. Essentially, this gland is located on the floor of the mouth.

As it is in a superficial location, it can be located very easily if the fingers are placed about two centimeters above the Adam’s apple.

It is the second largest salivary gland and produces the most saliva (up to 65%). It is considered a mixture of serous and mucous glands, since the suspension is rich in enzymes and sticky mucus that is released into the oral cavity through the submandibular ducts.

Sublingual glands

These are found under the tongue. They are the smallest and most dispersed salivary gland.

Its secretion is mainly mucus, and it exits directly through the excretory ducts of Rivinus. Only a minimal amount (~ 5%) of saliva in the oral cavity comes from these.

Innervation of the salivary glands

The salivary glands are innervated by both branches of the autonomic or “involuntary” nervous system. This is commonly associated with the fight or flight response.

When a person is exposed to danger, the sympathetic response is triggered. Threats trigger the release of norepinephrine, an increase in heart rate, dilation of the eyes, and in particular slower digestion and a dry mouth.

This means that while sympathetic stimulation normally overstimulates its target, it inhibits the salivary gland. So less saliva is produced. In contrast, parasympathetic stimulation of the salivary gland produces a large flow of saliva.

Salivary gland disorders

Several diseases can affect your salivary glands. These range from cancerous tumors to Sjögren’s syndrome. While some conditions clear up with time or antibiotics, others require more serious treatments, including surgery.

What Causes Salivary Gland Disorders?

Blocked salivary glands are the most common source of problems. These blocked glands can cause painful symptoms.

Sialolithiasis and sialadenitis

Sialolithiasis and sialadenitis can occur in the salivary glands:

  • Sialolithiasis occurs when calcium stones form in the salivary glands. These stones can block the glands and can partially or completely stop the flow of saliva.
  • Sialadenitis (or sialadenitis) is an infection that involves a salivary gland. It often results from stones blocking the gland. Staph or strep bacteria can cause this infection. Older adults and babies are more likely to develop this condition.

Sjogren’s syndrome

Sjögren’s syndrome is another common salivary gland disorder. It occurs when white blood cells target healthy cells in the moisture-producing glands, such as saliva, sweat, and oil glands. This condition most often affects women with autoimmune disorders, such as lupus.


Viruses can also affect the salivary glands. These include:

  • Flu virus.
  • Mumps.
  • Virus coxsackie.
  • Cytomegalovirus.

Cancerous and non-cancerous tumors

Cancerous and non-cancerous tumors can also develop in the salivary glands. Cancerous tumors of the salivary glands are rare. When they do occur, it is typically 50 to 60 years of age.

Non-cancerous tumors that can affect the parotid glands include pleomorphic adenomas and Warthin’s tumors. Benign pleomorphic adenomas can also grow in the submandibular gland and minor salivary glands, but this is rare.

What are the symptoms of a salivary gland disorder?

Symptoms of sialolithiasis include:

  • Painful lump under the tongue.
  • Pain that increases when eating.

Symptoms of sialadenitis include:

  • Lump on the cheek or under the chin.
  • Pus draining into your mouth.
  • Strong or smelly pus.
  • Fever.

Cysts that grow in your salivary glands can cause:

  • Yellow mucus that drains when the cyst bursts.
  • Difficulty eating
  • Difficulty speaking
  • Difficulty to swallow.

Viral infections of the salivary glands, such as mumps, can cause:

  • Fever.
  • Muscle pains.
  • Joint pain
  • Swelling on both sides of the face
  • Headache.

Symptoms of Sjögren’s syndrome include:

  • Dry mouth.
  • Dry eyes.
  • Tooth decay.
  • Sores in the mouth
  • Joint pain or swelling
  • Dry cough.
  • Unexplained fatigue
  • Swollen salivary glands.
  • Frequent salivary gland infections.

If you have diabetes or alcoholism, you may also have swollen salivary glands.

If you notice the following symptoms, see your doctor:

  • A bad taste in the mouth.
  • Dry mouth.
  • Mouth pain
  • Facial swelling
  • Trouble opening your mouth

How are salivary gland disorders diagnosed?

Your doctor will recommend the tests based on your medical history and a physical exam. Some cases are quite obvious just from the history and physical examination. In such cases, diagnostic tests may not be necessary.

Your doctor may want to see the blockage to diagnose a salivary gland blockage. Taking a dental X-ray of the affected area can help identify the obstruction. A head and neck surgeon can use anesthesia to numb the salivary gland opening and release any obstructions.

If your doctor needs to target the salivary glands, an MRI or CT scan can provide deeper images.

Also, a biopsy to remove tissue from your salivary glands can aid in the diagnosis, especially if your doctor suspects that you may have an autoimmune disorder that affects your salivary glands.

How are salivary gland disorders treated?

Treatment of salivary gland disorders depends on the type of disease and its degree of progression.

For example, if you have a mass in your salivary gland, your doctor may recommend surgery to remove the mass or gland. If the mass is cancerous, you may need radiation treatments to kill the cancer cells.

These treatments usually won’t start until your body has had time to heal. This is typically four to six weeks after surgery.

Radiation treatments to the neck can cause a dry mouth, which can be uncomfortable and affect your digestion. Your doctor may recommend drinking more fluids and avoiding foods that are high in sodium.

If the salivary gland mass is not cancerous, radiation may not be required. A mass that does not cause symptoms can be treated with conservative measures. This includes special mouthwashes to relieve dry mouth.

You can also keep your mouth moist by rinsing with a mixture of 1/2 teaspoon of salt in 1 cup of water and antibiotics can treat bacterial infections.

Taking good care of your teeth is vital to successful salivary gland treatment. Brushing and flossing your teeth at least twice a day can help prevent salivary gland disorders and tooth decay.