Researchers at the University of Basel in Switzerland recently discovered a new muscle layer sitting on the back of the cheeks.
As indicated in a Mail Online report, the researchers discovered that the newly found muscle layer plays a vital role in helping a person when chewing.
The human body has unceasingly amazed scientists who recently identified an overlooked layer of muscle in the lower jaw.
Previously, the masseter muscle was described as having a single superficial and one deep part. However, an additional, even deeper layer was discovered after the scientists dissected about 12 human heads donated to the laboratory.
The New Layer of Masseter Muscle
The new layer, which scientists have identified as M. masseter pars coronoidea, masseter's part of coronoid, can be felt by pressing the hand against the back of the jaw while chewing.
In a statement, Dr. Szilvia Mezey from the Department of Biomedicine at the University of Basel said the deep section of the masseter muscle is distinguishable from the two other layers regarding its function and course.
The muscle fibers' arrangement is involved in the steadying of the lower jaw, according to Dr. Mezey. It appears to be the lone part of the masseter that can pull back the lower jaw toward the ear.
A Work with 12 Human Heads
Mezey and her team, started work with 12 human heads, which were preserved in formaldehyde after being brought for donation to the lab.
Portions of the superficial masseter were cut away, having the deep masseter exposed that was also taken out. The study published in the Annals of Anatomy journal indicated that the temporal muscle's attachment onto the coronoid process also turned clearly visible, marking the right depth for trading the attachment of the masseter's third, deepest layer the pars coronoideus.
The masseter's coronoid part was determined by its diagonally-running fibers, lying beneath the deep masseter, coin posteriorly from the zygomatic arch's temporal side, and run towards the mandible's coronoid process diagonally-interiorly.
Possibility of a Third Muscle Layer
Earlier studies have discussed the possibility of a third muscle later in the masseter. However, the scientists divided the region into two layers because they could not agree on a standard.
Even though studies have hinted at a third layer, many of the works positioned it in different parts of the jaw, deeming it "extremely inconsistent."
According to the University of Center for Dental Medicine Basel's Jens Christoph Türp, "In view of these conflicting descriptions, they wanted to investigate the masseter muscle's structure again comprehensively, Granthshalan News said in a similar report.
Even though it is generally assumed that no stone was left unturned in the person's anatomy, the new study's finding is a bit like zoologists discovering a new vertebrate species.
Related information about masseter muscle is shown on Mohammed Nour's YouTube video below:
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