Muscles of mastication
846583
197404254
2008-03-11T03:55:47Z
Arcadian
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/* Muscles */ describe [[sphenomandibularis]]
{{Infobox Muscle |
Name = {{PAGENAME}} |
Latin = musculi masticatorii |
GraySubject = 109 |
GrayPage = 385 |
Image = Gray781.png |
Caption = Mandibular division of the trifacial nerve. |
Image2 = |
Caption2 = |
Origin = |
Insertion = |
Blood = |
Nerve = [[mandibular nerve]] |
Action = |
Antagonist = |
DorlandsPre = m_22 |
DorlandsSuf = 12549778 |
}}
[[Mastication]] is accomplished through the activity of the four '''muscles of mastication'''.
==Muscles==
*The [[masseter]]
*The [[temporalis]] (the [[sphenomandibularis]] is considered a part of the temporalis by some sources, and a distinct muscle by others)
*The [[Medial pterygoid muscle|medial pterygoid]]
*The [[lateral pterygoid]]
Each of these primary muscles of mastication is paired, with each side of the mandible possessing one of the four.
==Innervation and embryological origin==
Unlike most of the other facial muscles, which are innervated by the [[facial nerve]], or [[CN VII]], the muscles of mastication are all innervated by the [[trigeminal nerve]], or [[CN V]]. More specifically, they are innervated by the [[mandibular nerve|mandibular branch]], or [[mandibular nerve|V<sub>3</sub>]]. This is a testament to their shared embryological origin from the first [[branchial arch]].
The [[muscles of facial expression]], on the other hand, derive from the second branchial arch.
==Origin and insertion==
In humans, the [[mandible]], or lower jaw, is connected to the [[temporal bone]] of the skull via the [[temporomandibular joint]], an extremely complex joint which permits movement in all planes. The muscles of mastication originate on the skull and insert into the mandible, thereby allowing for jaw movements during contraction.
==Function==
The mandible is the only bone that moves during mastication and other activities, such as talking.
While these four muscles are the primary participants in mastication, other muscles are usually if not always helping the process, such as those of the tongue and the cheeks.
==External links==
* {{MeshName|Masticatory+Muscles}}
* http://anatomy.med.umich.edu/head/infratemp_lecture.html
{{anatomy-stub}}
{{Muscles of head}}