The Salivary Glands

Course ID
Salivary

Anatomy and physiology of the salivary glands

The salivary glands produce and secrete a fluid called saliva. Saliva contains water, electrolytes, mucus and enzymes. Salivary glands are considered exocrine glands because they secrete their product into ducts. Saliva enters the mouth through these ducts.

Structure

The salivary glands can be divided into major and minor types.

Major salivary glands

The 3 major pairs of salivary glands are the parotid, submandibular and sublingual glands.

Parotid glands

The parotid gland is the largest salivary gland. It is located in front of the ear on the side of the face. The facial nerve runs through the parotid gland and divides it into a superficial lobe and deep lobe. The facial nerve controls the muscles of the face, including the forehead, cheek, eye and mouth. Five branches of the facial nerve lie within the parotid gland. These branches include the temporal, zygomatic, buccal, mandibular and cervical nerves. The mandibular and buccal nerves are the most important nerves as they are responsible for the movement the eyelid and lip, respectively.

Stenson’s duct carries saliva from the parotid gland to an opening at the back of the mouth near the upper second molar.

Submandibular glands

The submandibular gland is smaller than the parotid gland. It is located behind the lower jaw, just under the chin and tongue. There are 3 important nerves that lie close to the submandibular gland. They are the lingual nerve, the hypoglossal nerve and the marginal branch of the facial nerve.

Wharton’s duct carries saliva from the submandibular gland to openings on the floor of the mouth on either side of the tongue.

Sublingual glands

The sublingual gland is the smallest of the major salivary glands. The gland is located deep in the floor of the mouth. Saliva from the sublingual gland enters the mouth through many small sublingual ducts.

Minor salivary glands

Minor salivary glands are very small. Many are too small to be seen with the naked eye. There are about 750–1000 minor salivary glands are spread throughout the upper airway and digestive tract. They are located in the oral cavity and oropharynx. About half of all minor salivary glands are located on the roof of the mouth (hard palate). Minor salivary glands are also found in the nose, nasal cavity, paranasal sinuses, nasopharynx, larynx and trachea.

Function

Salivary glands produce saliva, which plays an important role in digestion to break down food. It prevents infections of the mouth and throat and helps to maintain healthy teeth. Saliva also moistens the oral cavity, which helps with swallowing and speaking.

What is salivary gland cancer?

Salivary gland cancer is a malignant tumour that starts in cells of a salivary gland. Malignant means that it can spread, or metastasize, to other parts of the body.

The salivary glands make a fluid called saliva. Saliva helps you digest food. It also protects your mouth and throat from infection. There are 3 pairs of major salivary glands. The parotid glands are in front of each ear on either side of your face. The submandibular glands are behind the lower jaw, just under the tongue. The sublingual glands are under the tongue, deep in the floor of the mouth. There are also hundreds of small minor salivary glands in your upper airway and digestive tract.

Cells in a salivary gland sometimes change and no longer grow or behave normally. These changes may lead to non-cancerous, or benign, tumours such as pleomorphic adenoma (also called benign mixed tumour) or papillary cystadenoma lymphomatosum (also called Warthin’s tumour).

In some cases, changes to salivary gland cells can cause cancer. Mucoepidermoid carcinoma (MEC) is the most common type of salivary gland cancer. It usually develops in the parotid gland. Adenoid cystic carcinoma is the second most common type of salivary gland cancer. It usually develops in a minor salivary gland. Other types of cancer can also develop in the salivary glands, including acinic cell carcinoma and salivary duct carcinoma.

Very rare types of salivary gland cancer can also develop. These include mixed malignant tumours, carcinoma ex-pleomorphic adenocarcinoma and polymorphous low-grade adenocarcinoma (PLGA).

Salivary gland tumours occur most often in the parotid gland, but these tumours are usually benign. Tumours that develop in the submandibular glands and minor salivary glands are more likely to be malignant.

 

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