What is the Submandibular Duct?

The submandibular gland is one of three major salivary glands. The other two are the parotid gland and the sublingual gland.

Salivary glands produce saliva, which then drains through salivary ducts. Saliva keeps your mouth lubricated and is essential for good oral health.

Various conditions can affect the function of the salivary glands. Facial swelling, the feeling of a dry mouth, and abnormal tastes can indicate a problem with the salivary glands.

This article explains the anatomy and function of the submandibular gland and duct and the common conditions that can affect it.

What is the Submandibular Duct?

The submandibular duct, called Wharton’s duct, is the submandibular gland’s main excretory duct. It drains saliva from the submandibular gland into the floor of the mouth at the base of the tongue.

Wharton’s duct is about 5cm long and 1.5mm in diameter. It connects to the submandibular gland, which is the second largest salivary gland. The parotid gland is the only salivary gland larger than the submandibular.

What is the Function of the Submandibular Gland?

The submandibular gland produces about 70% of your saliva when unstimulated. However, the parotid gland produces more than 50% of saliva during chewing.

Saliva lubricates your mouth and is essential for oral health. Its continuous presence on the surfaces of the teeth and mouth is necessary for:

• Swallowing
• Initiating digestion
• Remineralizing tooth enamel
• Buffering the pH of your mouth
• Maintaining good dental hygiene and a healthy oral microbiome

How is Saliva Produced?

Saliva is secreted by the three major salivary glands and about a thousand smaller minor glands. The major salivary glands include:

• Parotid gland
• Submandibular gland
• Sublingual gland

The autonomic nervous system regulates saliva production. The submandibular gland receives sensory input from the facial nerve via the submandibular ganglion.

The submandibular and sublingual glands respond to sensory input (for example, from the scent of food) by secreting saliva. The parotid gland responds more strongly to the action of chewing.

Where is the Submandibular Duct Located?

Wharton’s duct begins at the submandibular gland and runs behind the mylohyoid muscle in the neck. There are two submandibular glands and, therefore, two ducts.

The submandibular gland is located at the bottom of the submandibular triangle. The submandibular triangle is located beneath the mandible (or the lower jaw).

Wharton’s duct crosses over the lingual nerve and opens into the oral cavity beneath the tongue. The opening is called the sublingual caruncle. There’s one on either side of the lingual frenulum (the tissue connecting the tongue to the floor of the mouth).

Conditions Affecting the Salivary Glands

Many health conditions can affect the salivary glands. The submandibular and parotid glands are most commonly affected because of their size and location.

Salivary gland dysfunction affects adults and children. The most common conditions include:

Sialadenitis

Sialadenitis is a salivary gland infection. Acute bacterial or viral infections can cause this. Common viruses and bacteria that cause sialadenitis include:

• Staphylococcus aureus bacteria
• Paramyxovirus (mumps)
• Hepatitis C
• Herpes
• HIV

Inflammation from the infection causes a rapid decline in salivary gland function. Treatment involves addressing the underlying condition. However, salivary gland function may be reduced even after the infection clears.

Sialolithiasis

This disease occurs when small stones block a salivary gland excretory duct. The blockage leads to symptoms like pain and swelling around the affected gland or duct. The pain may worsen when eating.

About 80% to 90% of salivary gland stones occur in Wharton’s duct and come from the submandibular gland. This is likely because saliva flows against gravity when it moves through the submandibular gland. Decreased saliva flow can cause stone formation.

Sialolithiasis can be treated with minimally invasive salivary gland surgery to remove the stones.

Sjörgen’s Syndrome

Sjörgen’s syndrome is an autoimmune disease that causes a loss of salivary gland function. It also affects the lacrimal (tear) glands in the eyes.

This disease causes the immune system to attack healthy mucous cells in these glands. Mucous cell loss results in symptoms such as dry mouth and eyes.

The exact cause of Sjörgen’s syndrome is unknown. It often occurs in women and people with other autoimmune disorders, such as rheumatoid arthritis and lupus. There’s currently no effective treatment.

Medication-Induced Xerostomia

Xerostomia is the medical term for dry mouth. It happens when salivary gland function declines. Dry mouth can lead to tooth decay, bad breath, and difficulty chewing and swallowing.

Many medications cause dry mouth as a side effect. These include:

• Certain antidepressants
• Drugs that treat high blood pressure
• Antimuscarinic drugs that treat pulmonary disease and irritable bladder

Other types of medications may also cause this side effect. Talk to your doctor or pharmacist if you’re concerned about xerostomia. They may be able to switch you to a different medication.

Malignant and Benign Tumors

Salivary gland tumors can be malignant (cancerous) or benign (non-cancerous). And about 50% of submandibular gland tumors are cancerous.

The most common malignant tumors include mucoepidermoid carcinoma and adenoid cystic carcinoma. Additionally, head and neck cancer tumors can metastasize (spread) to the major salivary glands.

Benign and low-grade malignant tumors can be treated surgically with submandibular gland excision. More advanced or aggressive tumors can be treated with neck surgery and radiation therapy. Chemotherapy might be necessary as well.

Summary

The submandibular duct is also called Wharton’s duct. It serves as the excretion duct for the submandibular gland, one of three main salivary glands. These glands secrete saliva, which protects the teeth and aids in essential functions like digestion.

The submandibular glands and ducts usually function without a problem, but certain conditions can affect them. Trouble swallowing, facial pain, fever, and prolonged facial swelling are all signs of a submandibular gland problem that may require treatment.