Author: Jana Vasković•Reviewer: Francesca Salvador MScLast reviewed: September 30, 2021Reading time: 7 minutes
Masseter muscle is a paired, strong, thick and also rectangular muscle that is originating native the zygomatic arch and extends under to the mandibular angle. It consists of a superficial and a deep part.
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It is just one of the masticatory muscles, a group of muscle which likewise includes the temporal muscle, lateral pterygoid muscle and medial pterygoid muscle. Its specific functions room elevation and protrusion that the mandible, as well as providing support to the articular capsule that the temporomandibular joint.
This short article will covering the anatomy and role of the masseter muscle.
|Origin||Superficial part: maxillary procedure of zygomatic bone, worse border the zygomatic arch (anterior 2/3)Deep part: deep/inferior surface ar of zygomatic arch (posterior 1/3)|
|Insertion||Lateral surface ar of ramus and also angle of mandible|
|Innervation||Masseteric nerve the mandibular nerve (CN V3)|
|Blood supply||Masseteric artery|
|Function||Elevates and protrudes mandible|
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Origin and also insertion
The superficial part of the muscle that lies over its deep component originates from the maxillary process that the zygomatic bone. It then runs inferoposteriorly to the masseteric tuberosity found ~ above the lower part of the superficial next of the ramus that the mandible.
The deep component consists of vertically command muscle fibers. This component originates native the entire length of the inferior border that the zygomatic arch, and inserts onto the superficial side of the ramus the mandible, exceptional to the insertion of the superficial component of the muscle.
With this position, the muscle have the right to be easily palpated from the dental cavity along the cheek. Furthermore, some of the deep yarn radiate into the anterior capsule and articular bowl of the temporomandibular joint.
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The whole superficial (lateral) aspect of the muscle is spanned with thin but very solid masseteric fascia.
Also ~ above the superficial side, listed below the zygomatic process, the duct that the parotid gland passes throughout the surface ar of the muscle. This duct courses mostly end the anterior component of the lateral aspect, i.e. It is located anterolaterally.
The superficial part of the gland itself is also located superficially come the masseter, however a bit an ext posteriorly, i.e. posterolaterally to the muscle.
Along through the parotid gland, a few more structures can be uncovered over the lateral side of the muscle:
The medial, or inner, surface ar of the muscle is mainly related ramus of mandible almost fully covering that superficial surface.
The medial aspect of the masseter muscle creates the lateral wall surface of the facial room called the submasseteric space. That is a paired potential an are between the lateral element of the mandible and medial aspect of the masseter muscle.Located deep to the posterior component of the inner aspect of the muscle, or merely posteromedially, the temporal muscle is found.
Anterior come the muscle, the buccinator muscle is located. The abovementioned duct the the parotid gland actually penetrates the fibers of the buccinator muscle to uncover its way to the within of the oral cavity and also finally open onto the inner side of the cheek.
The posterior facet of the muscle is located anteriorly to the deep component of the parotid gland. This practically way that the parotid gland surrounding the entire posterior and also most that the superficial element of the muscle.
Masseter (mandibular) reflex
The routine neurological examination contains testing the the jaw jerk reflex, also known together the masseter or mandibular reflex. The examiner locations his index finger top top the chin that the patient and also taps the finger v the reflex hammer. In healthy people, the stretch that the masseter provokes one upward activity of the mandible.
In order to produce much better results, that is advantageous to asking the patient to relax and also slightly open up his or her mouth and also close the eyes. A pathological jaw jerk reflex deserve to indicate a lesion of the trigeminal nerve but if this seems quite unlikely (e.g. Intact facial sensation, well developed masseter muscle on both political parties etc.), one has actually to consider a brainstem lesion.
Infections and submasseteric abscesses
Under some conditions, specifically while infected v the bacteria Clostridium tetani, strong and persistent spasms that the masseter muscle deserve to occur. That kind of convulsion is called trismus, and can interfere v the common feeding process.
Since the masseter muscle is affiliated with submasseteric an are that was explained before, it has an important role once it concerns submasseteric abscesses. This abscesses are relatively rare, so they room easily confused with parotid gland infections. The origin of the infection is commonly odontogenic, native pericoronitis in the mandibular third molar, especially when the apices that the tooth lies an extremely close come or in ~ the space. Together a result, the infection generally spreads conveniently to this an ar where these abscesses tend to it is in chronic.
A major hallmark the a submasseteric room infection is the upper stated trismus, therefore the masseter is actually sending signals the the epidemic is all about submasseteric room instead of any surrounding structures.
By knowing the relations and also functions the the masseter muscle, we can easily narrow under our differential diagnosis options for the patient that is suffering from some form of facial lesion.
References :R. L. Drake, A. V. Vogl, A. W. M. Mitchell: Gray’s Anatomy because that Students, third edition, Churchill Livingstone (2015), p. 977-978K. M. Valve Der Graaff, D. Strete, C. H. Creek: human being Anatomy, sixth edition, McGraw-Hill (2002), p. 250-251S. V. Jovanovic, N. A. Jelicic, A. Ilic et al.: Anatomija čoveka II, Medicinski fakultet Univerziteta u Beogradu (2015), p. 18-22
Illustrators:Masseter muscle (dorsal view) - Yousun Koh
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