Lecture #5 - Salivary Glands

A gland is a

structure that produces a chemical secretion necessary for normal bodily functions

Glandular tissue in the head and neck includes:

• Lacrimal

• Salivary

• Thyroid

• Parathyroid

• Thymus

CLASSIFICATION OF GLANDS - 2 major types:

Exocrine and endocrine

Exocrine gland

• A gland that has a duct associated with it

• Produce substances — (not hormones) — that are released through ducts to the exterior of your body, such as sweat, saliva, and tears.

• This passageway allows the secretion to be emptied directly into the location where the secretion is being used.

  • Ex. Salivary, lacrimal, sebaceous

Endocrine gland

• A ductless gland with secretions being poured directly into the vascular system and then carried to the area being used.

• Make hormones and release them into your bloodstream

  • Ex. Adrenal, thyroid, hypothalamus

EXOCRINE GLANDS - The salivary glands produce…  

saliva and are controlled by the autonomic nervous system (ANS)

• done unconsciously 

Saliva is a

• *Watery secretion with a stable pH of around 7 (neutral)

• Referred to as the “mouth’s bloodstream”

• Plays an important role in bolstering and maintaining the health of oral soft and hard tissues

Saliva is made up of: 

•  Salivary amylase, an enzyme that begins starch digestion in the mouth.

• Lingual lipase, an enzyme that is activated by stomach acid and digests fat after the food is swallowed

• Mucus, which binds and lubricates the food mass and aids in swallowing

• Lysozyme, an enzyme that kills bacteria and other pathogens

•  Immunoglobulin A (IgA), an antibody that inhibits bacterial growth; and

•  Electrolytes, including sodium, potassium, chloride, phosphate, and bicarbonate ions

Functions of saliva

• Helps prepare the bolus of food for easier swallowing

• Helps to keep the mucous membranes lubricated

• Helps prevent dehydration; dry mouth stimulus to drink water pH buffer

• Breaks down starches (carbohydrates)

• Cleanses teeth

• Neutralizes acids to prevent tooth decay

• Aids in taste

Development of a salivary gland

• Arise from a cord of epithelium

• Grows to forms a tube

• End of tube either round or tubelike clusters

• Acini—cluster of secretory cells forms at the end of the tube

What are acini?

• Secretory end pieces

• Secrete proteins

There are three kinds of acinar cells:

• Serous acini

• Mucous acini

• Seromucous acini

TYPES OF SECRETIONS: Serous

• Secretion is thinner and more watery

• Less viscous

• No mucins

TYPES OF SECRETIONS: Mucous

• Secretion is slightly viscous

• 99% water

• Inorganic ions (e.g., sodium, potassium, and chloride)

• Minor amounts amylase

• *Has mucins: key characteristic is their ability to form gels

TYPES OF SECRETIONS: Seromucous

Has characteristics of both types of secretions

The salivary glands are divided into major and minor exocrine glands, meaning they have…

Ducts 

• help drain the saliva directly into the oral cavity where the saliva can function

What salivary gland makes up the bulk of saliva?

the major salivary glands

The major salivary glands are…

large paired glands and have named ducts associated with them

The three major salivary glands include:

• Parotid glands

• Submandibular glands

• Sublingual gland

The parotid salivary gland is the…

largest encapsulated major salivary gland

The parotid salivary gland is divided into two lobes:

the superficial and deep lobes

*The parotid gland produces…

*25% of saliva 

• serous secretions

The parotid salivary gland is innervated by the…

9th and 5th cranial nerves

• 7th cranial nerve travels through it, not an innervation 

The parotid salivary gland occupies the…

parotid space, an area posterior to the mandibular ramus, anterior and inferior to the ear

The duct associated with the parotid salivary gland is the…

parotid duct or Stensen’s duct

• P.S.

Parotid salivary gland ducts

• This long duct emerges from the anterior border of the gland, superficial to the masseter muscle.

• The duct pierces the buccinator muscle, and then opens up into the oral cavity on the inner surface of the buccal mucosa of the cheek, usually opposite the maxillary second molar.

The parotid papilla is a

small elevation of tissue that marks the opening of the parotid duct on the

inner surface of the cheek

CLINICAL NOTE: PAROTID GLAND PATHOLOGY

The parotid salivary gland becomes enlarged and tender when a patient has mumps

Mumps

This contagious viral infection usually involves inflammatory enlargement or parotitis of both glands, first one side and then the other, giving the characteristic “chipmunk” cheeks

The submandibular salivary gland is the...

second largest encapsulated major salivary gland

The submandibular salivary gland produces….

Produces 60-65% of saliva

• Mucous and serous secretions

The submandibular salivary gland is located…

• Occupies the submandibular fossa in the submandibular space, mainly in its posterior part

• Posterior to the sublingual gland

  • Wraps around the mylohyoid muscle

  • Floor of the mouth

The submandibular salivary gland ducts

the duct associated with this gland is the submandibular duct or Wharton’s duct

• Upside down M is W

The submandibular salivary gland duct….

Travels along the anterior floor of the mouth then opens into the oral cavity at the sublingual caruncle, a small papilla near the midline of the floor of the mouth on each side of the lingual frenum

The submandibular salivary gland is innervated by

7th cranial nerve

The sublingual salivary gland is the

smallest, most diffuse, and only unencapsulated major salivary gland

The sublingual salivary gland produces…

10% of total salivary volume

• Mixed serous and mucous secretion

The sublingual salivary gland location…

occupies the sublingual fossa in the sublingual space at the floor of the mouth

The sublingual salivary gland ducts

The short ducts associated with the gland sometimes combine to form the sublingual duct or Bartholin’s duct

• B for bartholin's 

Also has Ducts of Rivinus

The sublingual duct…

opens directly into the oral cavity through the same opening as the submandibular duct, the sublingual caruncle

The sublingual caruncle is…

a small papilla near the midline of the floor of the mouth on each side of the lingual frenum

Other smaller ducts of the sublingual salivary gland, Ducts of Rivinus…

open along the sublingual fold, a fold of tissue on each side of the floor of the mouth

The sublingual salivary gland is innervated by…

7th cranial nerve

The minor salivary glands are…

• Smaller than the larger major salivary glands

• More numerous in number

• Not individually encapsulated

  • Surrounded by connective tissue within the submucosa

Most of the minor salivary glands are

mainly scattered throughout the oral cavity

• in the buccal, labial, and lingual mucosa, the soft palate, the posterior part of the lateral zones of the hard palate, and the floor of the mouth

Minor salivary glands are also

von Ebner’s glands

von Ebner’s glands are…

associated with the base of the large circumvallate lingual papillae on the posterior part of the tongue’s dorsal surface

The minor salivary glands are also found in…

lesser numbers along the mucosa of the tonsils, supraglottis region, and paranasal sinuses as well as between the muscle fibers of the tongue

The minor salivary glands are NOT found in…

the gingival tissue and the anterior part of the lateral zones of the hard palate or its medial zone

• Because it is a keratinized tissue

Each minor salivary gland has a single duct that

secretes saliva directly into the oral cavity since they are exocrine glands like the major salivary glands

The unnamed ducts of the minor salivary glands are

shorter than those of the major salivary glands

*All the minor salivary glands have a

mucous secretion EXCEPT FOR the glands of von Ebner which have a mainly serous secretion

The minor salivary glands are innervated by

various nerves depending on location

*CLINICAL NOTE: SALIVARY GLAND

PATHOLOGY: LESIONS

• May become enlarged, tender, and possibly firmer due to various disease processes.

• *They may also become involved in the formation of a salivary stone (or sialolith) within the gland, blocking the drainage of saliva from the duct, especially with the submandibular gland.

• This can cause gland enlargement and tenderness in the major glands (with a ranula) or minor glands (with a mucocele)

Salivary stones are

• Uncomfortable but not dangerous

• Can involve one or more enlarged, tender salivary glands

• Clinician may be able to palpate the stony hard salivary stone(s) during an examination

• Facial radiographs or computed tomography (CT) can confirm the diagnosis

• Salivary stones are usually removed manually or with minor surgery

Sialolithiasis is when…

When a salivary stone becomes lodged within the duct, causing a blockage of saliva. The gland usually swells and feels painful, especially around meal times, and infection may follow

CLINICAL NOTE: SALIVARY GLAND

PATHOLOGY: XEROSTOMIA

• Certain medications, disease, or destruction of salivary tissue by radiation therapy may result in hyposalivation by the salivary glands, which is a reduced production of saliva.

• Xerostomia (DRY MOUTH) can result in increased trauma to a nonprotected oral mucosa, increased cervical caries, problems in eating, speech and mastication, and bad breath or halitosis

  • Extensive cervical caries is a frequent complication of dry mouth. In addition to the lack of saliva, patients may attempt to stimulate salivary flow with sweets or chewing gums

Treatment for dry mouth

• Being very vigilant about good oral hygiene through brushing and flossing

• Using a toothpaste that has a heavy fluoride content (Prevident 5000)

• Sip water frequently

• Eat soft moist foods that are not overly salty

• Avoid rinses that contain alcohol

• Use products to moisturize your mouth including prescription or over-the- counter mouth rinses, artificial saliva or moisturizers to lubricate your mouth.

• Mouthwashes designed for dry mouth, especially ones with xylitol. Ex. Biotene or ACT mouthwashes

• Prescribe medication that stimulates saliva. Ex. pilocarpine (Salagen) to stimulate saliva production

Summary

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