The constitution and shape of superior head of the lateral pterygoid muscle (SHLP) inserts remains a topic of interest in the literature. The purpose of this study was to analyze by magnetic resonance imaging (MRI) the temporomandibular joint (TMJ) of individuals without signs of temporomandibular dysfunction. One hundred seventy-eight MRI images of one hundred and three patients were utilized, and the surface and percentage of the SHLP insert into the articular disc and condilar process was determined. In women, the average insertion into the disc was found to be between 5.7-5.5mm (SD 1.5-1.3), corresponding to 69.8-70.7% of the SHLP. In men, the average insertion into the disc was between 6.2-6.12mm (SD 1.8-1.9), or 68.9-74.2%. There were no differences in terms of the sex of the patients or the side of the joint. We found a significant percentage of SHLP fibers embedded in the disc of asymptomatic TMJs, and its role in the anterior disc displacement and the development of the temporomandibular dysfunction should be revised.