Editing Muscles of mastication

{{Short description|Muscles that aid chewing}}
{{Infobox muscle
| Name        = Muscles of mastication
| Latin       = musculi masticatorii
| Image       = Gray781.png
| Caption     = Mandibular division of the trigeminal nerve
| Image2      =
| Caption2    =
| Origin      =
| Insertion   =
| Blood       =
| Nerve       = [[Mandibular nerve]]
| Action      =
| Antagonist  =
}}
The four classical '''muscles of mastication''' elevate the [[mandible]] (closing the jaw) and move it forward/backward and laterally, facilitating biting and chewing. Other muscles are responsible for opening the jaw, namely the [[Geniohyoid muscle|geniohyoid]], [[mylohyoid muscle|mylohyoid]], and [[Digastric muscle|digastric]] muscles (the [[lateral pterygoid muscle|lateral pterygoid]] may play a role).

==Structure==
The muscles are:
* The [[masseter]] (composed of the superficial and deep head)
* 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 muscle|lateral pterygoid]]

In humans, the [[Human mandible|mandible]], or lower jaw, is connected to the [[temporal bone]] of the skull via the [[temporomandibular joint]]. This is 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.

Each of these primary muscles of mastication is paired, with each side of the mandible possessing one of the four.

===Innervation===
Unlike most of the other [[facial muscles]], which are innervated by the [[facial nerve]] (or [[CN VII]]), the muscles of mastication are  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>]]. The mandibular nerve is both sensory and motor.

===Development===
Embryologically, the muscles of mastication are all derived from the first [[pharyngeal arch]].

The [[muscles of facial expression]], on the other hand, are derived from the second pharyngeal arch.

==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 help with the process, such as those of the tongue and the cheeks.
{| class="wikitable"
! Prime mover 
! Movement<ref name="Openstax Anatomy & Physiology attribution">{{CC-notice|cc=by4|url=https://openstax.org/books/anatomy-and-physiology/pages/11-3-axial-muscles-of-the-head-neck-and-back}} {{cite book|last1=Betts|first1=J Gordon|last2=Desaix|first2=Peter|last3=Johnson|first3=Eddie|last4=Johnson|first4=Jody E|last5=Korol|first5=Oksana|last6=Kruse|first6=Dean|last7=Poe|first7=Brandon|last8=Wise|first8=James|last9=Womble|first9=Mark D|last10=Young|first10=Kelly A|title=Anatomy & Physiology|location=Houston|publisher=OpenStax CNX|isbn=978-1-947172-04-3|date=June 28, 2023|at=11.3 Axial muscles of the head, neck and back}}</ref><ref>{{Citation |last=Hansen |first=John T. |title=HEAD AND NECK |date=2010 |url=http://dx.doi.org/10.1016/b978-1-4377-0272-9.50014-0 |work=Netter's Clinical Anatomy |pages=349–445 |access-date=2024-01-08 |publisher=Elsevier|doi=10.1016/b978-1-4377-0272-9.50014-0 |isbn=978-1-4377-0272-9 |url-access=subscription }}</ref>!! Origin !! Insertion
|-
| '''[[Masseter]]''' 
! Elevates mandible (closes mouth and aids chewing)
| [[Zygomatic arch]]|| Mandible ([[Coronoid process of the mandible|coronoid process]] and [[Ramus mandibulae|ramus]])
|-
| '''[[Temporalis]]''' 
! Elevates and retracts mandible (closes mouth; pulls lower jaw in/backward)
| [[Temporal bone]] || Mandible (coronoid process and ramus)
|-
| [[Lateral pterygoid muscle|'''Lateral pterygoid''']]
! Depresses?, protracts, laterally moves mandible (opens mouth?; pushes lower jaw out/forward; moves lower jaw side to side)
| ''Superior head'': infratemporal surface of greater wing of [[sphenoid bone]]
''Inferior head'': [[lateral pterygoid plate]] of sphenoid bone
| Mandible; temporo-mandibular joint
|-
| [[Medial pterygoid muscle|'''Medial pterygoid''']]
! Elevates, protracts, laterally moves mandible (closes mouth; pushes lower jaw out/forward; moves lower jaw side-to-side)
| ''Deep head'': medial surface of [[lateral pterygoid plate]] and [[palatine bone]]
''Superficial head'': tuberosity of [[maxilla]] 
| Mandible (medial ramus below the [[mandibular foramen]])
|}

==Clinical significance==
* [[Temporomandibular joint disorder]]
* [[Bruxism]]
==References==
{{reflist}}

==External links==
{{Commons category|Muscles of mastication}}
* {{MeshName|Masticatory+Muscles}}
* http://www.med.umich.edu/lrc/coursepages/m1/anatomy2010/html/nervous_system/infratemp_lecture.html

{{Muscles of head}}
{{Authority control}}

[[Category:Muscles of the head and neck]]
[[Category:Chewing]]