The Anatomy of the Sublingual Glands

The sublingual glands lie on the floor of your mouth, under your tongue. Shaped like almonds, they’re the smallest of the three pairs of salivary glands.

The sublingual glands produce very little saliva—only between 3% and 5% of the total volume—and make secretions composed predominantly of mucus, a slippery liquid that lubricates and protects organs. The secretions produced by the sublingual glands aid in the earliest stages of digestion and keep the inside of your mouth moist.

“Lingual” refers to the tongue and “sub” means below, so the word "sublingual" literally means below the tongue.

Anatomy

Location

The sublingual glands lie just inside the jawbone (mandible) behind your lower canine teeth. They’re also on either side of the genioglossus muscle, which allows you to stick out your tongue and move it side to side. The glands actually connect to each other in the front of your mouth, creating a U-shape.

Structure

This U wraps around the front of what’s called the lingual frenulum, which is the band of mucous membrane that connects the floor of your mouth to the center of your tongue. The blood supply for the sublingual glands comes from the sublingual and submental arteries. Nerve function of these glands comes from the chorda tympani (secretomotor nerve fibers) and lingual branch of the mandibular nerve (sensory fibers).

Secretions produced by the sublingual glands drain into your mouth through ducts called minor sublingual ducts, or ducts of Rivinus. Each duct has between eight and 20 ducts. Some people with abnormal duct structure have a major sublingual duct, also called the duct of Bartholin.

Anatomical Variations

Known anatomical variations of the sublingual glands include:

• Different distances from the mandible
• Larger size due to hypertrophy (increase in the size of cells)
• An abnormal duct structure, including a major sublingual duct (duct of Bartholin)
• Absence of the glands

Variations like these are important for healthcare providers to know when diagnosing and treating conditions related to the sublingual glands and their associated structures. Especially during surgical procedures, being aware of potential deviations from what’s considered standard can help prevent accidental damage to the glands.

Function

The sublingual glands are considered mixed glands because they produce both mucus and serous fluid, a clear to pale yellow watery fluid that is found in the body. However, it primarily produces a thick mucus. It lubricates the tissues of your mouth, helps you digest food, and allows you to swallow it.

In addition, the fluid produced by these glands is protective of your teeth and helps maintain the pH balance in your mouth.

Associated Conditions

The sublingual glands can be involved in a number of medical conditions:

• Ranula: Cysts (fluid-filled sacs) may develop after infections, surgery, or trauma, which may allow secretions to leak from the damaged gland. 
• Sialolithiasis: Salivary stones that form in the glands may block the ducts, partially or completely, stopping the flow of saliva into the mouth. Enlarged glands and infections may develop as well.
• Viral infections: Mumps, influenza, and other viruses can enlarge the salivary glands.
• Sjögren’s syndrome: This autoimmune disease targets glands that produce moisture, including the salivary and tear glands. Sjögren’s increases the risk of salivary gland cancers.
• Cancer: Cancer, including lymphoma, which is more common in the parotid and submandibular glands.
• Sialadenitis: Sialadenitis is a painful infection and inflammation of a salivary gland. It is more common in the parotid and submandibular glands.
• Sialadenosis: This refers to a painless enlarged salivary gland without a known cause. It is more common in the parotid gland.

Tests

The tests your healthcare provider performs on your sublingual glands depend on what conditions are suspected based on your symptoms, a physical exam, and possibly blood tests. Tests for various conditions connected to the sublingual glands may include:

• Sialadenitis: An examination of the glands via a scope
• Sjögren’s syndrome: Salivary function tests using filter paper, salivary gland function scan or scintigraphy (nuclear medicine test), lip biopsy 
• Duct-related problems: Sialogram X-ray using dye to show the flow of saliva
• Suspected stones or tumors: X-ray, computed tomography (CT) scan, or magnetic resonance imaging (MRI)
• Cancer: Fine-needle biopsy

Summary

The sublingual glands produce liquid that help keep your mouth moist and break down food for digestion. Different conditions, such as cancer and cysts, can interrupt the functioning of these glands and cause problems.