The salivary glands are several exocrine glands located within the tissue of the oral cavity region with openings in the mouth.
The salivary glands produce and excrete a watery substance called saliva, contributing the digestion.
Glands are classified regarding their size and duct types, and salivary glands can be divided into two groups: the major and minor salivary glands.
The major glands are primary glands moistening, lubricating and protecting the oral cavity. The saliva starts the chemical food procession in the oral cavity.
There are three pairs of major salivary glands:
- Parotid gland - the largest of the salivary glands, lying on each lateral side of the face in front of the auricle of the ear; it is located in the region around the ramus of the mandible and lies anterior to the masseter muscle, extending upward to the zygomatic arch, downward to the mandible and mandibular angle, and reaching the external acoustic meatus posteriorly; the parotid gland is covered by the parotid fascia; it has two lobes - the superficial and deep; the parotid gland secretes saliva via parotid duct (also known as the Stensen's duct) that goes through the cheeks and opens in the oral cavity with a papilla opposite the second maxillar molar tooth;
- Submandibular gland - lies in the submandibular fossa of the mandible beneath the muscles of the floor of the mouth; each gland is located next to the mandible and the anterior and posterior bellies of the digastric muscle; it has two parts - superficial and deep; the duct of the submandibular gland (known as the Wharton's duct) curves around the mylohyoid muscle, passes medially across the diaphragm of the oral cavity, and opens on the undersurface of the tongue in the oral cavity proper - on the sublingual caruncle;
- Sublingual gland - the smallest of the major salivary glands; each gland lies above the muscles of the inferior wall of the oral cavity on the mylohyoid muscle and is covered by mucosa; it has one main duct called the Bartholin duct and several minor ducts called Rvinus ducts; the main duct joins with the duct of the submandibular gland and also opens on the sublingual caruncle.
There are also numerous minor salivary glands embedded in the mucosa of the oral cavity, composing the following sets of glands:
- Labial glands in the lips
- Buccal glands in the cheeks
- Palatine glands in the palate
- Molar glands between the masseter and buccinator muscles
- Lingual glands in the tongue
Minor salivary glands mainly function only for the lubrication of the oral cavity.
Saliva is produced in the mouth by the salivary glands, and it contains such components as water, mucus, electrolytes, antibacterial substances, and enzymes.
The main functions of the saliva include:
- Breaking down some components of the food
- Lubricating and moistening ingested food
- Contributing to the initiation of swallowing
- Protecting the mucosa of the upper alimentary tract
- Protecting the teeth from bacterial decay