ArticlesAnatomyHead and neckOral cavitySalivary glands

ArticlesAnatomyHead and neckOral cavitySalivary glands

Salivary glands

Author: Alexandra Sieroslawska, MD • Reviewer: Dimitrios Mytilinaios, MD, PhD
Last reviewed: October 30, 2023
Reading time: 10 minutes

The salivary glands are exocrine glands which produce a digestive fluid called saliva. They are accessory organs of the digestive system and are positioned in the head, in and around the oral cavity and secrete their salivary contents into the mouth.

The salivary glands are divided into the major and minor salivary glands:

The major glands include the parotid, submandibular and sublingual glands. They are much larger in size and are a collection of exocrine tissue that secretes as a whole into a salivary duct rather than acting individually and therefore end up producing a much larger amount of saliva per day than the minor glands.
The main role of the minor glands is to lubricate the walls of the oral cavity, while digestive and protective saliva is produced by the major glands.

Functionally, the salivary glands contribute to digestion through the enzymes they excrete with saliva, mainly amylase that starts the digestion of carbohydrates. They also help in the initial stages of digestion during mastication of food, so that a food bolus is created and ready to be swallowed for further processing. Additionally, they help keep the oral mucosa protected and lubricated.

The glands vary widely in their size, but also are classified based on the nature of the saliva they excrete. This article will discuss the anatomy and clinical importance of the salivary glands.

Key facts
Definition	Saliva producing exocrine glands which are accessory organs of the digestive system
Types of glands	Serous: parotid gland Mucous: sublingual gland, minor salivary gland Mixed: submandibular gland
Parotid gland	Location: between ramus of mandible and sternocleidomastoid muscle Excretory duct: Stensen's duct (opens on the buccal wall at the level of maxillary second molar)
Submandibular gland	Location: beneath the tongue Excretory duct: Wharton's duct (opens at sublingual papilla under tongue)
Sublingual gland	Location: beneath the sublingual fold Excretory duct: multiple ducts that open along sublingual folds
Minor glands	Location: bucca, labia, lingual mucosa, soft palate, hard palate
Function	Secrete saliva for initial phases of digestion and for protection and lubrication of oral cavity
Clinical relations	Cysts, inflammation, tumors

Contents

Saliva
Major glands
Minor glands
Clinical aspects
Sources

+ Show all

Are you an interactive learner? Then this salivary glands quiz is a handy study tool for you.

Saliva

Saliva is a seromucinous liquid that has several major functions within the oral cavity which include lubrication, digestion, antimicrobial action, buffering, hormone regulation and taste sensation. It contains 99.5% water and the rest is electrolytes, mucus, glycoproteins, enzymes and antibacterial compounds.

There are two major types of saliva that are secreted from the salivary glands and they are serous and mucous. The submandibular gland secretes both types in a 3:2 ratio of serous to mucous respectively. The parotid gland is the only gland that secretes purely serous saliva, while the sublingual gland and minor salivary glands secrete mainly mucous saliva.

The total daily output of saliva in an adult is between 1-1.5 liters of saliva.

Major glands

Parotid gland

The parotid gland is the largest of the major salivary glands and it sits bilaterally in between the ramus of the mandible and the sternocleidomastoid muscle. Although it is the largest by size, it doesn't produce the most saliva, however it does produces between 25-30% of the total daily salivary output which is released through Stensen’s duct (parotid duct) whose orifice can be seen on the buccal wall at the level of the maxillary second molar. Branches of the facial nerve can be easily seen exiting from substance of the gland, however the gland actually receives parasympathetic input from the glossopharyngeal nerve, not the facial nerve.

Submandibular gland

The submandibular gland is the second largest of the major salivary glands and like all three of them it is a paired gland. It produces by far the largest amount of saliva of all and account for up to 70% of the total daily output. Wharton’s duct (submandibular duct) opens at the sublingual papilla under the tongue, either side of the base of the lingual frenulum. It is a mixed gland, made up of serous and mucous acini and is located within the submandibular fossa. Each gland is divided into a large superficial and a smaller deep component anteriorly by the mylohyoid muscle. Unlike the parotid gland, the submandibular gland does receive parasympathetic supply from the facial nerve, via the chorda tympani.

Sublingual gland

Lastly, the sublingual gland is the smallest of the major salivary glands and is located in the floor of the mouth, deep to the sublingual fold. Like the other major salivary glands, it is also a paired gland, however it secretes the smallest portion of saliva per day, up to just 5%. The sublingual glands are unique in the fact that it they have several ductal openings that run along the margin of the sublingual folds through which saliva is secreted into the oral cavity. Unlike the parotid glands which produce serous saliva, the sublingual glands secrete entirely mucinous saliva. Similar to the submandibular gland, the sublingual gland receives its parasympathetic input from the chorda tympani branch of the facial nerve.

Test your knowledge on the salivary glands with this quiz.

Master the structure and function of the salivary glands with our study unit:

Minor glands

The minor salivary glands account for approximately 1% or less of the total daily salivary output. They can be found in patches around the oral cavity such as the bucca, the labia, the lingual mucosa, the soft palate, the lateral parts of the hard palate, the floor of the mouth and between the muscle fibers of the tongue.

They amount to approximately 800-1000 individual glands in total.

Clinical aspects

Salivary gland cysts can develop due to injuries, tumours, infections or salivary stones that can block the flow of saliva. Since it cannot escape into the ducts it remains within the tissues which start to swell as the saliva builds up.

This condition is usually painless but can cause problems when eating or speaking. Removal of the underlying cause will correct the problem and recurrence is uncommon.

Sources

All content published on Kenhub is reviewed by medical and anatomy experts. The information we provide is grounded on academic literature and peer-reviewed research. Kenhub does not provide medical advice. You can learn more about our content creation and review standards by reading our content quality guidelines.

References:

Neil S. Norton, Ph.D. and Frank H. Netter, MD, Netter’s Head and Neck Anatomy for Dentistry, 2nd Edition, Elsevier Saunders, Chapter 1 Development of the Head and Neck and Chapter 6 Parotid Bed and Gland, Page 186 to 196 and Chapter 13 Oral Cavity, Page 366 to 371.
Frank H. Netter, MD, Atlas of Human Anatomy, Fifth Edition, Saunders - Elsevier, Chapter 1 Head and Neck, Subchapter 6 Oral Region, Guide Head and Neck: Oral Region - Salivary Glands, Page 35 and 36.
Salivary Gland Problems. WebMD, LLC. http://www.webmd.com/oral-health/guide/salivary-gland-problems-infections-swelling.
A. Giorgi: Salivary Gland Infections. Healthline Networks, Inc. http://www.healthline.com/health/salivary-gland-infections.

Illustrators:

Sublingual gland (lateral view) - Paul Kim
Parotid gland (cadaveric dissection) - Prof. Carlos Suárez-Quian

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