The salivary gland is an essential component of the human oral cavity. The salivary gland secrete saliva which has a role in maintaining oral health and helping digestion. The salivary gland location is throughout the mouth and throat, including the sides of the cheeks, beneath the tongue, and below the jawbone. Understanding the salivary gland types and functions is crucial for learning the mechanisms of oral health and digestion.
Salivary Glands
Salivary glands are exocrine glands located in several places. The salivary glands secrete saliva which is a watery fluid that helps with chewing, swallowing, and digesting food. There are three main types of salivary glands: parotid glands, submandibular glands and sublingual glands. Each type has a specific location and function in the oral cavity. The saliva produced by these glands contains enzyme amylase that begin the process of breaking down food, making it easier to digest.
Also Read: What is Role of Saliva in Digestion of Food?
Diagram of Salivary Gland
The labeled diagram of Salivary Gland is given below:
Labeled Diagram of Salivary Gland
Salivary Glands Location
The salivary glands are located in your mouth and throat. They are positioned in different areas, including the sides of your cheeks, under your tongue, and below your jawbone. These glands produce saliva, which helps moisten food for easier swallowing and initiates the digestion process.
Salivary Glands Structure
The structure of salivary glands is made up of clusters of cells called acini, which produce saliva. These acini are connected to ducts that carry the saliva to the mouth. Surrounding the acini are blood vessels and nerves that regulate saliva production. Additionally, each type of salivary gland has its own unique arrangement of acini and ducts, suited to its specific function in the mouth.
Salivary Glands Types
The two types of salivary glands are:
- Major Salivary Glands - Larger than the minor glands. Made up of exocrine tissue that secretes into a salivary duct collectively rather than individually. As a result, they produce a lot more saliva each day than the minor glands.
- Minor Salivary Glands - Create digesting and protective saliva, the minor glands' primary function is to lubricate the walls of the oral cavity.
Also Read: Mouth and Buccal Cavity
Major Salivary Glands
The biggest and most significant salivary glands are known as the major glands. The majority of mouth's saliva is produced by these glands. The parotid glands, submandibular glands, and sublingual glands are the three pairs of major salivary glands.
Parotid Glands
The parotid glands are the largest salivary glands. They are situated just in front of the ears. A duct located next to upper second molar secretes the saliva produced by these glands into the mouth. The superficial lobe and the deep lobe are the two lobes that comprise each parotid gland.
The facial nerve is located between the two lobes which governs facial expressions like smiling, brow-raising, and eye closure. The external carotid artery, which supplies a significant amount of blood to the head and neck region, and the retromandibular vein, a branch of the jugular vein are two other important structures close to the parotid glands.
Submandibular Glands
The submandibular glands are situated below the jaw and are about the size of a walnut. These glands produce saliva, which is then secreted into the mouth from beneath the tongue. The superficial lobe and the deep lobe are the two components of the submandibular glands, just like the parotid glands. Structures near the submandibular glands are:
- Marginal mandibular nerve which makes you smile
- Platysma muscle which facilitates lip movement
- Lingual nerve which gives your tongue feeling
- Hypoglossal nerve allows the part of the tongue that helps with speaking and swallowing to move.
Sublingual Glands
It is almond-shaped gland, weighs around 3–4 g, and is the smallest of the three main salivary glands. The sublingual gland is located lateral to the genioglossus, medial to the sublingual fossa of the mandible, above the mylohyoid, and below the mucosa of the mouth floor. It is made up of a single main gland duct and numerous smaller ducts. With or close to the submandibular duct, Bartholin's duct (the primary duct) opens. Along the sublingual fold, a number of smaller ducts, the duct of Rivinus, open independently.
Minor Salivary Glands
The aerodigestive tract and mouth are covered in many little salivary glands. These glands, in contrast to the larger salivary glands, are too small to be seen without a microscope. The majority are located in the cheeks, nose, sinuses, larynx, the roof of the mouth, lining of the lips, tongue, and these areas (voice box).
Small salivary gland tumors are very rare. They are more likely to be malignant than benign. The roof of the mouth is where small salivary gland cancers most frequently start.
- Labial and buccal glands: These glands which have serous demilunes and mucous tubules are found on the cheeks and lips.
- Glossopalatine glands: These is situated in the glossopalatine fold, close to the isthmus although they may also extend from the soft palate glands to the posterior extension of the sublingual gland.
- Palatine glands: These are found in the submucosa of the soft palate and uvula as well as in the glandular aggregates seen in the lamina propria of the posterolateral portion of the hard palate.
Salivation
Salivation is regulated by neurons in specific brain areas called the salivatory nuclei, located near the junction of the dorsal pontomedullary. These neurons control the production of saliva in glands like the submandibular, sublingual, and parotid glands. The facial nerve's chorda tympani branch carries signals from the superior salivatory nucleus to the submandibular ganglion, where they stimulate saliva production.
Similarly, the lacrimal, nasal, and palatine glands are controlled by neurons in this nucleus. The sphenopalatine ganglion, connected to the facial nerve, also influences the lacrimal gland and nasal epithelium. Neurons in the inferior salivatory nucleus, linked to the glossopharyngeal nerve and otic ganglion, regulate the parotid gland's function. These neurons respond to taste, smell, and mechanical stimulation in the mouth.
Functions of Saliva
The various functions of saliva are:
- Helps in chemical digestion which uses "salivary amylase" to break down starch.
- Helps with swallowing and chewing.
- It lubricate and hydrates the inside of the mouth and helps in speech.
- Food is broken down by the solvent effect, enabling the tongue to taste it.
- Removes food particles and microorganisms still present in the mouth.
- Lactoferrin, peroxidase, and lysozyme combat harmful germs.
- Prevents abrupt pH fluctuations.
- Provides nutrients to teeth, such as calcium and phosphorus.
Salivary Gland Disorders
Salivary gland disorders includes a range of conditions that affect the function and health of the salivary glands. These disorders can cause discomfort, pain, and difficulty with eating and speaking. Understanding the common disorders associated with the salivary glands can help individuals recognize symptoms early and seek appropriate treatment. Some of these diseases are:
Salivary Gland Swollen or Sialadenitis
Swollen salivary glands are also called Sialadenitis. It refers to inflammation of the salivary glands, often caused by bacterial infections. Symptoms include swelling, pain, and tenderness in the affected gland, along with fever and difficulty opening the mouth. Prompt treatment with antibiotics is essential to prevent complications such as abscess formation.
Sialolithiasis
Sialolithiasis occurs when stones, or calculi, form within the ducts of the salivary glands, obstructing the flow of saliva. This can lead to pain and swelling, especially during meals, as well as infection and inflammation. Treatment may involve manual manipulation to dislodge the stone, or in severe cases, surgical removal.
Salivary Gland Tumors
Salivary gland tumors can be benign or malignant growths that develop within the tissues of the salivary glands. Symptoms vary depending on the size and location of the tumor but may include swelling, pain, numbness, and difficulty swallowing. Treatment typically involves surgical removal of the tumor, with additional therapy such as radiation or chemotherapy for malignant tumors.
Conclusion - Salivary Glands
In conclusion, salivary glands have a role in maintaining oral health and helping in the digestion process. They are located throughout the mouth and throat. These glands produce saliva, a watery fluid that helps with chewing, swallowing, and breaking down food. The three main types of salivary glands – parotid, submandibular, and sublingual – each have distinct locations and functions in the oral cavity. Saliva contains enzymes like amylase that start the digestion process by breaking down starches. Additionally, the regulation of salivation involves complex neural pathways, with specific brain areas controlling saliva production in response to various stimuli. Understanding the structure and function of salivary glands is essential for recognizing and managing salivary gland disorders.
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