Parotid gland
331749
225112906
2008-07-11T23:00:28Z
24.109.16.198
/* Innervation */
{{Infobox Anatomy |
Name = {{PAGENAME}} |
Latin = glandula parotidea |
GraySubject = 177 |
GrayPage = 693 |
Image = Illu_quiz_hn_02.jpg |
Caption = [[Salivary gland]]s:<BR><BR>#1 is [[Parotid gland]]<BR>#2 is [[Submandibular gland]]<BR>#3 is [[Sublingual gland]] |
Image2 = |
Caption2 = |
Precursor = |
System = |
Artery = |
Vein = |
Nerve = [[otic ganglion]] |
Lymph = [[preauricular deep parotid lymph nodes]] |
MeshName = Parotid+Gland |
MeshNumber = A03.556.500.760.464 |
DorlandsPre = g_06 |
DorlandsSuf = 12392553 |
}}
''For the toad wart, see [[parotoid gland]].''
The '''parotid gland''' is the largest of the [[salivary gland]]s. It is found wrapped around the [[mandibular ramus]], and it secretes saliva through [[Stensen's duct]] into the oral cavity, to facilitate [[mastication]] and swallowing.
==Anatomy==
===Location===
The parotid gland is found in the [[subcutaneous tissue]] of the [[face]], overlying the [[mandibular ramus]] and anterior and inferior to the [[external ear]]. The gland occupies the '''parotid fascial space''', an area posterior to the mandibular ramus, anterior and inferior to the ear. The gland extends irregularly from the zygomatic arch to the angle of the mandible. This gland is effectively palpated bilaterally. Start anterior to each ear and move to the cheek area and then inferior to the angle of the mandible (''Illustrated Head and Neck Anatomy'', Fehrenbach and Herring, Elsevier, 2007, p. 170-1).
The [[facial nerve]] and its branches pass through the parotid gland, as does the [[external carotid artery]], which gives off its two terminal branches, the [[maxillary artery]] and the [[superficial temporal artery]], inside the gland.
Posteriorly, it is related to the posterior belly of the [[digastric]], the [[stylohyoid]], and the [[sternocleidomastoid]].
The parotid gland resembles a three sided pyramid. The apex of the pyramid is directed downwards. the gland has four surfaces:
(1) superior
(2) superficial
(3) anteromedial &
(4) posteromedial.
The surfaces are separated by three borders:
(1) anterior
(2) posterior &
(3) medial.
===Excretory portion===
The [[parotid duct|duct]] to this [[gland]] (also known as [[Stensen's duct]]) empties within the [[buccal cavity]] (the inside of the cheek) opposite the upper second molar. The '''parotid papilla''' is a small elevation of tissue that marks the opening of the parotid duct on the inner surface of the cheek (''Illustrated Dental Embryology, Histology, and Anatomy'', Bath-Balogh and Fehrenbach, Elsevier, 2006, p. 166).
[[Serous fluid]] (as opposed to mucous fluid) is produced by the parotid gland.
===Innervation===
Although the [[facial nerve]] ([[Cranial nerves|CN]] VII) runs ''through'' this gland, it does ''not'' control it.
[[Secretion]] of [[saliva]] by the parotid gland is controlled by presynaptic [[parasympathetic]] fibres originating in the [[inferior salivatory nucleus]]; these leave the brain via the [[glossopharyngeal nerve]] (CN IX), travel along the [[tympanic nerve]] (of Jacobson), pass through the [[tympanic plexus]] (located in the [[middle ear]]), and then travel in the [[lesser petrosal nerve]] until they reach the [[otic ganglion]]. After synapsing in the [[Otic ganglion]], the [[postganglionic]] fibers travel as part of the [[auriculotemporal nerve]] (a branch of the [[mandibular nerve]] (V<sub>3</sub>)) to reach the parotid gland.
[[Sympathetic]] nerves originating from [[Superior Cervical Ganglion]] reach the gland with blood vessels.
[[Parasympathetic]] stimulation produces a water rich [[serous]] [[saliva]]. [[Sympathetic]] stimulation leads to the production of low volume [[enzyme]] rich saliva. There is no inhibitory nerve supply to the gland.
===Vascularization===
Branches of the [[external carotid artery]] traverse the glandular tissue and supply the parotid gland with oxygenated blood. The main branch to supply the gland is the [[transverse facial artery]], whereas numerous local veins drain the organ. These veins drain into tributaries of external and [[internal jugular vein]]s.
The maxillary vein and superficial temporal vein meet to form the retromandibular vein within the parotid gland, but are not responsible for draining it.
Lymphatics mainly comprise [[pre-auricular lymph nodes]].
==Pathology==
Inflammation of one or both parotid glands is known as [[parotitis]]. The most common cause of parotitis is [[mumps]]. Widespread vaccination against mumps has markedly reduced the incidence of mumps parotitis. Other infections such as bacterial infections can cause parotitis as may blockage of the duct, whether from [[salivary duct calculi]] or external compression. Stones mainly occur within the main confluence of the ducts and within the main parotid duct. The patient usually complains of intense pain when salivating and tends to avoid foods which produce this symptom. In addition the parotid gland may become enlarged upon trying to eat. The pain can be reproduced in clinic via squirting lemon juice into the patient's mouth. Surgery depends upon the situation of the stone, if within the anterior aspect of the duct a simple incision into the buccal mucosa with sphinterotomy may allow removal, however if further posterior within the main duct, complete gland excision may be necessary.
The most common of tumors in the parotid gland are benign and only affect the superficial gland. These include [[pleomorphic adenoma]] and [[adenolymphoma]]. Their importance is in relation to their anatomical position. The tumorous growth can also change the consistency of the gland and cause '''facial pain''' on the involved side since the facial nerve travels through the gland (''Illustrated Head and Neck Anatomy'', Fehrenbach and Herring, Elsevier, 2007, p. 172). Critically, the relationship of the tumor to the branches of the [[facial nerve]] ([[cranial nerve|CN]] VII) must be defined because resection may damage the nerves, resulting in paralysis of the muscles of facial expression. If the tumor is deep within the gland, the patient should give consent for potential damage of the facial nerve.
==Additional images==
<gallery>
Image:Gray781.png|Mandibular division of the trifacial nerve.
Image:Gray843.png|Sympathetic connections of the otic and superior cervical ganglia.
Image:Gray908.png|Horizontal section through left ear; upper half of section.
Image:Gray1200.png|Outline of side of face, showing chief surface markings.
image:WVSOM Parotid Gland1.JPG|microscopic ducts surrounded by connective tissue
</gallery>
==See also==
* [[Parotitis]]
* [[Sjögren's syndrome]]
* [[John Leonora]]
==External links==
* [http://www.yoursurgery.com/procedures/parotidectomy/images/ParotidAnat1.jpg Illustration at yoursurgery.com]
* {{NormanAnatomy|lesson4}}
* [http://www.usc.edu/hsc/dental/ohisto/Cards/sal/02_tns.html Histology at usc.edu]
* {{eMedicineDictionary|Parotid+gland}}
* [http://www.breitbart.com/article.php?id=071207145613.hnkq6bin&show_article=1 Israeli study says regular mobile use increases (parotid gland) tumour risk]
{{Head and neck general}}
[[Category:Digestive system]]
[[Category:Mouth]]
[[ar:غدة نكفية]]
[[de:Ohrspeicheldrüse]]
[[es:Parótida]]
[[fr:Parotide]]
[[is:Vangakirtill]]
[[it:Ghiandola parotide]]
[[la:Glandula parotidea]]
[[pl:Ślinianka przyuszna]]
[[pt:Glândula parótida]]
[[sr:Доушна жлезда]]
[[fi:Korvasylkirauhanen]]