BASEL, Switzerland: Researchers at the University of Basel recently discovered a new muscle layer on a human head involved in stabilising the lower jaw.
Szilvia E.Mezey, the lead author of the research, and colleagues studied the masseter muscle again in detail. They found that the muscle consists of an additional third layer apart from two layers (superficial and deep) already described in textbooks. The team proposed that this new layer could be named Musculus masseter pars coronidea – the coronoid section of the masseter because it is attached to the lower jaw's muscular (or "coronoid") process.
The new muscle layer is different from the other two masseter layers in terms of its course and function, i.e., it is involved in stabilising the lower jaw. Musculus masseter pars coronidea pulls the lower jaw backwards, i.e., towards the ear.
The study was based on a thorough examination of formalin-fixed jaw musculature, CT scans and the analysis of stained tissue sections from deceased individuals who had donated their bodies to science and an MRI data of living individuals.
The research titled, 'The human masseter muscle revisited: First description of its coronoid part' has recently been published online in Annals of Anatomy.
