Figure 1: Salivary glands
Humans have three paired major salivary glands (parotid, submandibular, and sublingual) as well as hundreds of minor salivary glands.
Parotid gland: The two parotid glands are major salivary glands wrapped around the mandibular ramus. The largest of the salivary glands, they secrete saliva to facilitate mastication and swallowing, and amylase to begin the digestion of starches. It is the serous type of gland which secretes ptyalin. It enters the oral cavity via the parotid duct (Stensen duct).
Submandibular gland: The submandibular glands are a pair of major salivary glands located beneath the lower jaws, superior to the digastric muscles. The secretion produced is a mixture of both serous fluid and mucus, and enters the oral cavity via the submandibular duct or Wharton duct. Around 65–70% of saliva in the oral cavity is produced by the submandibular glands.
Sublingual gland: The sublingual glands are a pair of major salivary glands located inferior to the tongue, anterior to the submandibular glands. The secretion produced is mainly mucous in nature; however, it is categorized as a mixed gland. The ductal system of the sublingual glands does not have intercalated ducts and usually does not have striated ducts either, so saliva exits directly from 8–20 excretory ducts known as the Rivinus ducts. Around 5% of saliva entering the oral cavity comes from these glands.
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