Expression of MyHC isoforms mRNA transcripts in different regions of the masseter and medial pterygoid muscles in chimpanzees

The superficial portion of the masseter and the medial pterygoid muscle have the same expression pattern regarding the different MyHC isoforms. On the other hand, the deep portion of the masseter, which is activated mainly during lateral and repositioning movements of the mandible, has a lower MyHC-IIM isoform expression than the superficial portion. Our findings provide new data on functional aspects of the masseter and medial pterygoid that can complement results obtained by other techniques.