Anatomical Substract of the Temporal Muscle Myofascial Trigger Points in Fresh Cadavers

Abstract

BackgroundMyofascial syndrome is a common cause of chronic musculoskeletal pain and is characterized by myofascial trigger points (MTPs). MTPs are clinically identified by palpation of a muscle or fascial taut band. Although pathophysiology of MTPs remains unclear, coincidence between them and muscle motor plate at the innervation zone (IZ) have been reported. The temporal muscle is related to headache and temporomandibular disorders and pain radiates from hyperalgesic points to distant areas symptomatic patients. Clinical reports usually describe four trigger points located in the temporal muscle and we aimed to identify anatomical correlation with muscle innervation.MethodsWe dissected the temporal muscles from five fresh cadavers to observe the exact point where nerve fibers penetrated the muscle belly. As muscle size varies among individuals, we calculated the relative entry point of the nerve into the muscle by defining six different areas in the muscle belly: three superior (I, II and III) and three inferior (IV, V and VI), beginning at the posterior margin of the muscle. Statistical analysis of anatomical data was obtained by Poisson distribution and logarithm link function followed by Bonferroni multiple comparisons. The comparison of points between the sides was made by Student’s t‐test. IBM‐SPSS for Windows version 20.0 software was used to perform the analysis, and Microsoft Excel 2003 software was used to tabulate the data. Data are presented as the mean ± standard deviation, and the level of significance was adjusted to 5% (p <0.05) for all tests.ResultsThe number of temporal nerve branches did not differ between sides. Areas II and V had the largest number of temporal nerve entry sites, with a mean of 3 (22%) and 5 (36%) points, respectively. Areas III and VI had a mean of 2 sites both (14%) and areas I and IV, one (7%).ConclusionIn accordance with the clinical literature, the branches of the temporal nerve in the temporal muscle corresponded to the described areas of the myofascial trigger points (MTPs). Anatomical correlations between MTPs may be a useful tool for a better understanding of the physiopathology of these disorders and may provide a rational basis for their treatment.