[Histological observations on structure of bundle bone in area of mylohyoid line]

The purpose of this study was to investigate the structure and the function of the part of the mandible where mylohyoid muscle originates. The bundle bone in the area of mylohyoid line and the tendon fibers on the surface of the bundle bone were observed by light microscopy and scanning and transmission electron microscopy. The conclusions were as follows: 1. It seemed that remodeling occurs frequently in bundle bone in the area of the mylohyoid line. 2. Sharpey's fibers in bundle bone in the area of the mylohyoid line seemed to be flexible. This suggested that Sharpey's fibers can be adapted to the tension from directions that are different to a certain degree. 3. Both directions of Sharpey's fibers in bundle bone in the area of the mylohyoid line and the tendon fibers on the surface of bundle bone were fundamentally the same as that of the muscle fibers of the mylohyoid muscle. But a few existing fibers crossed these fibers. Such Sharpey's fibers and tendon fibers seemed to prevent the exfoliation of the periosteum, and seemed to support main tendon fibers of the mylohyoid muscle when it is contracting.