Not taught in medical school
With millions of doctors performing complex surgery every day worldwide, you would think someone would have successfully described all parts of the human body right? Well, science is ever surprising, with researchers managing to pinpoint a muscle that is not taught in medical school.
“It’s 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,” said senior author Dr. Jens Christoph Türp.
A third layer
In modern anatomy textbooks the masseter muscle, located in the jaw, is commonly described as having two layers: one deep and one superficial. “However, a few historical texts mention the possible existence of a third layer as well, but they are extremely inconsistent as to its position,” the authors wrote in the paper published in Annals of Anatomy.
The team, from the University Center for Dental Medicine, Basel, investigated this inconsistency by combining data from 16 human cadaver head CT scans and 12 cadaver dissections. From this, they found a third layer of “anatomically distinct” masseter muscle. This structure runs from the cheekbone down to the lower jawbone and can be felt just in front of the ear.
Scientists named this newly discovered muscle “Musculus masseter pars coronidea”, which means “coronoid part of the masseter” in Latin. It is thought to stabilize the lower jaw and is the only layer of muscle That can pull the jawbone backward. This new finding has huge clinical importance, allowing doctors to perform better surgically and provide better treatment.
Source study: Annals of Anatomy – The human masseter muscle revisited: First description of its coronoid part