Introduction: The purpose of this study is to provide useful data by conducting a comprehensive study of the mylohyoid muscle and its related structures.
Materials and methods: Fifty-eight mandibles and 30 mylohyoid muscles from Korean adult cadavers were used. The shape and location of the mylohyoid line were analyzed by using digital calipers. The mylohyoid muscle and its herniation were observed using ultrasonography. After dissection, morphometric measurements of the muscle and herniation were conducted. The distribution pattern of the nerve to mylohyoid muscle was confirmed.
Results: The proportion of the distance between the cementoenamel junction and the mylohyoid line decreased from the mesiolingual cusp of the mandibular first molar (1:0.57) to the distolingual cusp of the mandibular second molar (1:0.41). The mylohyoid muscle was large, thick, and deep in men. Herniation was observed in 16 (53.3%) cases, and it was concentrated in the anterior one-third (52.2%) of the muscle. The richest arborization of the nerve to mylohyoid muscle was in the middle one-third (52.9%) of the muscle.
Conclusions: The results of the mylohyoid line can be applied in the reconstruction of the occlusal plane in edentulous patients. Differences between the sexes should be considered in the morphological characteristics of the mylohyoid muscle. Differential diagnosis of herniation is particularly important in the anterior one-third of the muscle. In the case of treatment with botulinum toxin in the mylohyoid muscle, it is recommended to inject into the middle one-third area considering the depth and thickness of the muscle in that area.
Keywords: herniation; mylohyoid line; mylohyoid muscle; nerve to mylohyoid muscle; ultrasonography.
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