Salivary gland and its various types


  • The tissue in our mouth that expels saliva is called salivary gland.
  • Various glands are responsible for secretion of saliva into the oral cavity.
  • But the salivary glands are mostly known by the three largest pairs: the parotid, submandibular, and sublingual glands.
  • They are exocrine glands that produce saliva through a system of ducts.
  • Salivary glands are classified as serous, mucous or sero-mucous (mixed).
  • It secretes saliva which is watery, tasteless mixture of salivary and oral-mucous gland secretions.
  • It helps in lubrication of chewed food, moistening the oral walls, and also contains salts to buffer chemicals in the mouth.
  • It also has salivary amylase, the enzyme that begins the digestion of carbohydrates.
  • There are six major salivary glands as well as hundreds of minor salivary glands that secrete more than a liter of saliva daily.

A) Parotid glands (Greek: parotis-near the ear)

  •  Among the three major types, parotid glands are the largest.
  • They are located in front of the ears, covering the masseter muscle posteriorly.
  • There are long ducts which arise from the glands that pass forward over the masseter muscles which can be felt as a ridge by moving the tip of a finger up and down over the muscle.
  • Vestibule is the end point of this duct which is alongside the second upper molar tooth.
  • These ducts are called Parotid or Stensens’s ducts.
  • These glands secrete water, salts, salivary amylase.
  •  Mucin is not secreted by this gland like other salivary glands.
  • Mucus is formed when mucin is dissolved in water.
  • For this reason, the saliva from parotid is clear and watery.

Related image       Image result for parotid glands

B) Sub-mandibular glands (Greek: submandibular- under the mandible)

  • They are located on the medial side of the mandible.
  • Their size is about the size of the walnut, which is roughly half the size of parotid glands.
  • Their ducts are called Submandibular or Wharton’s ducts.
  • These ducts open into a papilla on the floor of the mouth beside the lingual frenulum that is behind the lower incisors.
  • Water, salts, salivary amylase and mucin are secreted by these glands.
  • Their secretion is comparatively thicker with less salivary amylase than that of parotid.

C) Sublingual glands (Greek: sublingual- under the tongue)

  • They are located in the floor of the mouth beneath the tongue.
  • They are the smallest major salivary glands.
  • They drain their secretions through a dozen or so small ducts.
  • They are located on the summit of a fold on either side of the lingual frenulum.
  • These are the ducts that are just behind the orifice of the submandibular ducts.
  • Water, salts and mucin are mostly secreted.
  • Their secretion is the most viscous saliva among the three types of salivary glands.
  • Mucus content is high and salivary amylase is less.

Image result for sublingual ducts    Image result for sublingual ducts

 Composition and functions of saliva

  • It contains about 99% of water and 1% electrolytes and proteins.
  • It provides solvent for food in order for tasting and digestive reactions to occur.
  • It also moistens mouth and helps in speech.
  • Bicarbonates help in maintaining acidic pH of saliva at 6.35- 6.85.
  • Chlorides in saliva activate salivary amylase.
  • Immunoglobulin-A aids in antibacterial system.
  • Presence of lysozyme helps in destroying bacteria, prevents dental decay and infection of mucus membranes.
  • A protein mucin helps in forming mucus.
  • Mucus helps in lubricating food, helps from bolus, aids swallowing, help buffer acids and bases.
  • Phosphates help maintain pH of saliva.
  • Salivary amylase catalyzes the breakdown of carbohydrates.
  • Urea and uric acid are secreted as waste products and have no any digesting function.




Salivary gland and its various types