Masticatory muscles

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Muscles of mastication
Mandibular division of the trifacial nerve.
Latin	musculi masticatorii
Gray's	subject #109 385
Origin:
Insertion:
Blood:
Nerve:	mandibular nerve
Action:
Dorlands/Elsevier	m_22/12549778

Mastication is accomplished through the activity of the four muscles of mastication.

Contents 1 Muscles 2 Innervation and embryological origin 3 Origin and insertion 4 Function 5 External links

[edit] 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
• The lateral pterygoid

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

[edit] 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 branch, or V₃. 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.

[edit] 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.

[edit] 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.

[edit] External links

• MeSH Masticatory+Muscles
• http://anatomy.med.umich.edu/head/infratemp_lecture.html

This page uses content from the English-language version of Wikipedia. The original article was at Muscles of mastication. The list of authors can be seen in the page history. As with Psychology Wiki, the text of Wikipedia is available under the GNU Free Documentation License.