Salivary gland
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2008-06-25T01:17:24Z
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/* Sublingual Gland */
{{Unreferenced|date=December 2007}}
{{Infobox Anatomy |
Name = Salivary gland |
Latin = glandulae salivariae |
GraySubject = |
GrayPage = |
Image = Illu_quiz_hn_02.jpg |
Caption = [[Salivary glands]]: #1 is [[Parotid gland]], #2 is [[Submandibular gland]], #3 is [[Sublingual gland]] |
Image2 = Image:Parotid gland en.png|
Caption2 = Salivary+Glands |
MeshNumber = A03.556.500.760 |
DorlandsPre = g_06 |
DorlandsSuf = 12391916 |
}}
The '''salivary glands''' in [[mammals]] are [[exocrine gland]]s that produce [[saliva]]. In other organisms such as [[Insecta|insects]], salivary glands are often used to produce biologically important proteins like [[silk]] or glues, and [[fly]] salivary glands contain [[polytene chromosome]]s that have been useful in [[genetic]] research.
==Histology==
[[Image:Parotid gland en.png|thumb|right|Parotid gland (green) in relation to the skull.]]
The glands are enclosed in a capsule of [[connective tissue]] and internally divided into [[lobe|lobules]]. Blood vessels and nerves enter the glands at the [[hilum]] and gradually branch out into the lobules.
===Cells===
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 demilune]]s 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.
# [[Myoepithelium|Myoepithelial]] cells surround each secretory portion and are able to contract to accelerate secretion of the saliva.
===Ducts===
In the duct system, the lumens formed by steph [[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.
Salivary glands release saliva that dilutes the acid found in the stomach.
==Anatomy==
[[Image:Digestive system diagram en.svg|thumb|right|The salivary glands are situated at the entrance to the [[gastrointestinal system]] to help begin the process of digestion.]]
===Parotid Glands===
{{main|Parotid gland}}
The [[parotid glands]] are a pair of glands located in the [[subcutaneous tissues]] of the face overlying the [[mandibular ramus]] and anterior and inferior to the [[external ear]]. The secretion produced by the parotid glands is [[serous]] in nature, and enters the [[oral cavity]] through the [[Stensen's duct]] after passing through the [[intercalated ducts]] which are prominent in the gland. Despite being the largest pair of glands, only approximately 25% of saliva is produced by the glands.
===Submandibular Glands===
{{main|Submandibular gland}}
The [[submandibular gland]]s are a pair of glands located beneath the floor of the mouth, superior to the [[digastric muscle]]s. The secretion produced is a mixture of both [[serous]] and [[mucous]] and enters the [[oral cavity]] via [[Wharton's duct]]s. Approximately 70% of saliva in the oral cavity is produced by the submandibular glands, even though they are much smaller than the [[parotid glands]].
===Sublingual Gland===
{{main|Sublingual gland}}
The [[sublingual gland]]s are a pair of glands located beneath the floor of the mouth anterior to the [[submandibular gland]]s. The secretion produced is mainly [[mucous]] in nature, however it is categorized as a mixed gland. Unlike the other two major glands, the ductal system of the subligual glands do not have striated ducts, and exit from 8-20 excretory ducts. Approximately 5% of saliva entering the oral cavity come from these glands.
===Minor Salivary Glands===
There are over 600 minor salivary glands located throughout the [[oral cavity]] within the [[lamina propria]] of the [[oral mucosa]]. They are 1-2mm in diameter and unlike the other glands, they are not encapsulated by [[connective tissue]] only surrounded by it. The gland is usually a number of [[acini]] connected in a tiny lobule. A minor salivary gland may have a common excretory duct with another gland, or may have its own excretory duct. Their secretion is mainly mucous in nature (except for [[Von Ebner's glands]]) and have many functions such as coating the oral cavity with [[saliva]]. Problems with dentures are usually associated with minor salivary glands.<ref name="Cate3">Cate, A.R. Ten. ''Oral Histology: development, structure, and function.'' 5th ed. 1998. Page 3. ISBN 0-8151-2952-1.</ref>
====Von Ebner's Glands====
{{main|Von Ebner's glands}}
[[Von Ebner's glands]] are glands found in [[circumvallate papillae]] of the tongue. They secrete a serous fluid that begin lipid hydrolysis. They are an essential component of [[taste]].
==Innervation==
Salivary glands are innervated, either directly or indirectly, by the [[parasympathetic nervous system|parasympathetic]] and [[sympathetic nervous system|sympathetic]] arms of the [[autonomic nervous system]].
* ''Parasympathetic'' innervation to the salivary glands is carried via [[cranial nerve]]s. 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]].
* Direct ''sympathetic'' innervation of the salivary glands takes place via preganglionic nerves in the thoracic segments T1-T3 which synapse in the superior cervical ganglion with postganglionic neurons that release norepinephrine, which is then received by β-adrenergic receptors on the acinar and ductal cells of the salivary glands, leading to an increase in cyclic adenosine monophosphate (cAMP) levels and the corresponding increase of saliva secretion. Note that in this regard both parasympathetic and sympathetic stimuli result in an increase in salivary gland secretions. {{cite book
| last = Costanzo
| first = L.
| authorlink =
| coauthors =
| title = Physiology, 3rd ed.
| publisher = Saunders Elsevier
| date =2006
| location =
| pages =
| url =
| doi =
| id =
| isbn = 10:1-4160-2320-8}} The sympathetic nervous system also affects salivary gland secretions indirectly by innervating the [[blood vessel]]s that supply the glands.it is used to
==Role in disease==
:''See [[mumps]] (parotiditis epidemica), [[Sjögren's syndrome]] and [[Mucocele]].''
[[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]].
==References==
{{Unreferenced|date=June 2008}}
==External links==
* [http://www.intelihealth.com/IH/ihtIH/WSIHW000/9339/9658.html Salivary Gland Disorders at intelihealth.com]
* [http://www.merck.com/media/mmhe2/figures/fg111_1.gif Illustration at merck.com]
* [http://www.orthop.washington.edu/_Rainbow/Album/10357m26b8e09e-6490-41ab-8955-725a7a75ec05.gif Illustration at .washington.edu]
* [http://learning.mgccc.cc.ms.us/science/cat/sld012.htm Photo at mgccc.cc.ms.us]
* {{eMedicine|plastic|371}} - "Parotid Tumors, Benign"
{{Head and neck general}}
[[Category:Digestive system]]
[[Category:Mouth]]
[[Category:Glands]]
[[Category:Exocrine system]]
[[Category:Oral and maxillofacial surgery]]
{{Link FA|sr}}
[[ar:غدة لعابية]]
[[bs:Pljuvačne žlijezde]]
[[bg:Слюнчени жлези]]
[[cs:Slinná žláza]]
[[de:Speicheldrüse]]
[[dv:ކުޅުބޭރުކުރާ ގޮށް]]
[[es:Glándula salival]]
[[fr:Glande salivaire]]
[[hr:Žlijezde slinovnice]]
[[it:Ghiandola salivare]]
[[he:בלוטות רוק]]
[[ku:Toşbiya xweziyê]]
[[la:Glandulae salivariae]]
[[lt:Seilių liaukos]]
[[mk:Плунковна жлезда]]
[[nl:Speekselklier]]
[[ja:唾液腺]]
[[no:Spyttkjertlene]]
[[nn:Spyttkjertel]]
[[pl:Ślinianka]]
[[pt:Glândula salivar]]
[[simple:Salivary gland]]
[[sk:Slinná žľaza]]
[[sr:Пљувачне жлезде]]
[[fi:Sylkirauhanen]]
[[sv:Spottkörtlar]]
[[te:లాలాజల గ్రంధులు]]
[[tr:Tükürük bezleri]]
[[uk:Слинні залози]]
[[fiu-vro:Sülenääreq]]
[[zh:唾腺]]