There are still exciting new discoveries to be made in a field as well-studied as human anatomy, and researchers have confirmed the existence of a layer of muscle in the human jaw.
The third section of the masseter muscle is deeper. It's the most prominent jaw muscle and you can feel it moving by pressing your hand against the back of your jaw.
There has been suspicions that there is more to it than just two layers. Attempts to describe it have been confusing.
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The masseter muscle has three distinct sections, not two, and it has been established through an analysis of more than two dozen human heads.
Szilvia Mezey, from the Department of Biomedicine at the University of Basel in Switzerland, says that the deep section of the masseter muscle is distinguishable from the other layers.
The masseter muscle has a superficial, deep, and deeper layer. Jens C. Trp is from UZB.
The new muscle layer in the masseter is called Musculus masseter pars coronidea, and it is attached to the lower jaw.
The muscle fibers in Musculus masseter pars coronidea are arranged in a way that suggests that the newly discovered piece of anatomy plays an important role in keeping the lower jaw stable. It is closer to the jaw than the other two layers and is smaller in size.
The team was able to identify it as a separate entity because they were looking specifically for it. Previous studies had differing conclusions.
The structure of the masseter muscle was reexamined in view of the conflicting descriptions.
Detailed dissection of the heads left to medical science and magnetic resonance scans for the heads still attached to a living person were used to outline the position and function of the muscle layer. The coronoid part of the masseter could be identified in all of the cases studied.
It's not clear if any of the mammals have the same muscles as the Musculus masseter pars coronidea. It's possible that it's a human thing because it's missing in Chimpanzees. The researchers think that this might be investigated in the future.
The identification of this muscle layer could help with all kinds of surgical procedures and therapy treatments involving the lower jaw, after further study.
Trp says that their finding is a bit like zoologists discovering a new species of animal.
The research has been published.
