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The newly discovered muscle layer runs from the back of the cheekbone to the anterior muscular process of the lower jaw. (S= superficial layer, D= deep layer, C= coronoid layer) (Image credit: Jens. C. T\u00fcrp, University of Basel \/ UZB)<\/p>\n\n\n\n
Scientists recently uncovered a part of the body that had never been described before: a deep layer of muscle in the masseter, which raises the lower jaw and is critical for chewing.<\/p>\n\n\n\n
Modern anatomy textbooks describe the masseter muscle as having two layers, one deep and one superficial. <\/p>\n\n\n\n
\u201cHowever, a few historical texts mention the possible existence of a third layer as well, but they are extremely inconsistent as to its position,\u201d the study authors wrote in a new report, published on Dec. 2 in the online edition of the journal Annals of <\/p>\n\n\n\n
Anatomy. So the team decided to check whether the prominent jaw muscle might have a hidden, super-deep layer, as the historical texts suggest.<\/p>\n\n\n\n
To do so, they dissected 12 human cadaver heads that had been preserved in formaldehyde; they also took CT scans of 16 \u201cfresh\u201d cadavers and reviewed an MRI scan from a living subject, according to the report. <\/p>\n\n\n\n
Through these examinations, they identified an \u201canatomically distinct\u201d third layer of the masseter muscle. <\/p>\n\n\n\n
This deep, deep layer runs from the zygomatic process \u2014 a bony projection that forms part of the \u201ccheek bones\u201d and can be felt just in front of the ear \u2014 to the coronoid process \u2014 a triangular projection on the lower jawbone.<\/p>\n\n\n\n
\u201cThis deep section of the masseter muscle is clearly distinguishable from the two other layers in terms of its course and function,\u201d first author Szilvia Mezey, a senior lecturer in the Department of Biomedicine at the University of Basel in Switzerland, said in a statement. Based on the arrangement of the muscle fibers, the muscle layer likely helps stabilize the lower jaw by \u201celevating and retracting\u201d the coronoid process, the team wrote in their report. <\/p>\n\n\n\n
And in fact, the newfound muscle layer is the only part of the masseter that can pull the jawbone backward, Mezey said.<\/p>\n\n\n\n
\u201cAlthough it\u2019s generally assumed that anatomical research in the last 100 years has left no stone unturned, our finding is a bit like zoologists discovering a new species of vertebrate,\u201d senior author Dr. Jens Christoph T\u00fcrp, a professor and clinician at the University Center for Dental Medicine Basel, said in the statement. <\/p>\n\n\n\n
In their paper, the team proposed that the newfound muscle layer be named \u201cMusculus masseter pars coronidea,\u201d meaning \u201ccoronoid part of the masseter.\u201d <\/p>\n\n\n\n
The discovery could be important in a clinical context, because knowing about the muscle layer could help doctors to both better perform surgeries in that region of the jaw and better treat conditions involving the joint that joins the jawbone to the skull, they noted.<\/p>\n\n\n\n
<\/p>\n","protected":false},"excerpt":{"rendered":"
The newly discovered muscle layer runs from the back of the cheekbone to the anterior muscular process of the lower jaw. (S= superficial layer, D= deep layer, C= coronoid layer) (Image credit: Jens. C. T\u00fcrp, University of Basel \/ UZB) Scientists recently uncovered a part of the body that had never been described before: a […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[],"tags":[],"class_list":["post-245546","post","type-post","status-publish","format-standard"],"_links":{"self":[{"href":"https:\/\/nagalandpost.net\/index.php\/wp-json\/wp\/v2\/posts\/245546","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/nagalandpost.net\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/nagalandpost.net\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/nagalandpost.net\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/nagalandpost.net\/index.php\/wp-json\/wp\/v2\/comments?post=245546"}],"version-history":[{"count":0,"href":"https:\/\/nagalandpost.net\/index.php\/wp-json\/wp\/v2\/posts\/245546\/revisions"}],"wp:attachment":[{"href":"https:\/\/nagalandpost.net\/index.php\/wp-json\/wp\/v2\/media?parent=245546"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/nagalandpost.net\/index.php\/wp-json\/wp\/v2\/categories?post=245546"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/nagalandpost.net\/index.php\/wp-json\/wp\/v2\/tags?post=245546"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}