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|Salivary glands: #1 is Parotid gland, #2 is Submandibular gland, #3 is Sublingual gland|
The salivary glands in mammals are exocrine glands that produce saliva. In other taxa such as insects, salivary glands are often used to produce biologically important proteins such as silk or glues. Salivary glands have proven to be very useful to students of genetics due to the occurrence of polytene chromosomes that are common in the salivary gland cells of many Diptera.
Saliva keeps the mouth and other parts of the digestive system moist.
A summary is provided in the following table.
|Salivary gland||Location||Secretion||Cranial nerve||Parasympathetic ganglion|| Contribution to|
|Parotid gland||near the ear||Serous||CN IX (glossopharyngeal nerve)||Otic||25%|
|Sublingual gland||underneath the tongue||Mixed, mostly mucous||CN VII (facial nerve)||Submandibular||5%|
|Submandibular gland||ramus of the mandible||Mixed, mostly serous||CN VII (facial nerve)||Submandibular||70%|
|Ebner's glands||surrounding circumvallate papillae||Serous||-||-||-|
|minor glands||tongue, cheeks, lips, and palate||Mucous||-||-||-|
There are 3 main types of cells that are found in the major salivary glands:
- Serous cells, which are pyramidal in shape and are joined to usually form a spherical mass of cells called acinus, with a small lumen in the centre. Serous demilunes are found in the submandibular gland.
- Mucous cells are usually cuboid in shape and organised as tubules, consisting of cylindrical arrays of secretory cells surrounding a lumen. These cells produce glycoproteins that are used for the moistening and lubricating functions of saliva.
- Myoepithelial cells surround each secretory portion and are able to contract to accelerate secretion of the saliva.
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.
- Parasympathetic innervation to the salivary glands is carried via cranial nerves. The parotid gland receives its parasympathetic input from the glossopharyngeal nerve (CN IX) via the otic ganglion, while the submandibular and sublingual glands receive their parasympathetic input from the facial nerve (CN VII) via the submandibular ganglion.
- The sympathetic nervous system affects salivary gland secretions indirectly by innervating the blood vessels that supply the glands.
Role in diseaseEdit
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.
- ↑ Douglas F. Paulsen (2000). Histology & cell biology: examination and board review, New York: Lange Medical Books, McGraw-Hill. ISBN 0-8385-0593-7.
- Salivary Gland Disorders at intelihealth.com
- Illustration at merck.com
- Illustration at .washington.edu
- Photo at mgccc.cc.ms.us
- eMedicine plastic/371 - "Parotid Tumors, Benign"
General anatomy of head and neck - head
|Palate/roof of mouth|
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