A new muscle layer in human jaw discovered

Dec. 26: Scientists at the University of Basel, Switzerland have discovered a previously overlooked section of human jaw muscles. They described the structure of masseter muscle as consisting of an additional third layer and proposed to name it ‘Musculus masseter pars coronidea’. This new finding could rewrite anatomy textbooks.

The masseter muscle was previously described as having one superficial and one deep part, but an additional, even deeper layer was found after scientists dissected human heads donated to the lab. The new layer can be felt by pressing the hand against the back of the jaw while chewing. Dr Szilvia Mezey from the Department of Biomedicine at the University of Basel, said in a statement: ‘This deep section of the masseter muscle is clearly distinguishable from the two other layers in terms of its course and function.

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.