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The salivary glands produce saliva, which keeps the mouth and other parts of the digestive system moist. It also helps break down carbohydrates (with salivary amylase, formerly known as ptyalin) and lubricates the passage of food down from the oro-pharynx to the esophagus to the stomach. There are three main pairs of salivary glands: the parotid, the submandibular and the sublingual glands. There are also many small glands in the tongue, cheeks, lips and palate, all of which consist entirely of mucous secreting cells (see Histology below) except for the serous glands of von Ebner, which reside within the moats surrounding the circumvallate papillae in the posterior 1/3 of the tongue, anterior to the terminal sulcus.
Histology Two types of epithelial cells in salivary glands produce either mucous or serous secretions. The parotid gland produces serous secretions. The submandibular and submaxillary glands contain a mixture of both types of cells, and produce a mixture of the two liquids. Classification The salivary glands can be classified into serous, mixed and mucous glands. Structure The glands are enclosed in a capsule of connective tissue and internally divided into lobules. Blood vessels and nerves enter the glands at the hilum and gradually branch out into the lobules. There are 3 main types of cells that are found in the major salivary glands: In the duct system, the lumens formed by the secretory cells empty into intercalated ducts, which in turn join to form striated ducts. These drain into ducts situated between the lobes of the gland (called interlobar ducts or excretory ducts). The main duct of the salivary glands ultimately empties into the mouth. Location of the glands There are three salivary glands: Role in disease See mumps (parotiditis epidemica) and Sjögren syndrome. Salivary duct calculus may cause blockage of the ducts, causing pain and swelling of the gland. Tumors of the salivary glands may occur. These are usually benign, but may be malignant. The most common type of benign tumor is Pleomorphic adenoma, followed by Warthin's tumor. The most common malignant tumor is Mucoepidermoid carcinoma. Diagnostic investigation A sialogram is a radiocontrast study of a salivary duct. | |||||||||||||||||||||||||
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