Abstract

By means of anatomical examinations as well as radiograms and jaw models of probands the inclination angles of the fibers of the oral diaphragm inserting in the hyoid bone are determined in order to obtain information for shaping the lingual margins of complete lower dentures. The transition from these fibers to the fibers inserting in the median raphe of the mylohyoid muscle is about 6 to 9 mm before the tip of the alveolar tubercle in edentulous mandibles, and in the area between the roots of the second molars in dentulous lower jaws with normal position of molars. In this area the muscle has, in most cases, an angle of inclination between 30 and 40 degrees to the perpendicular plane. The inclination of the posterior fibers of the mylohyoid muscle is most frequently between 10 and 25 degrees. The difference in inclination is mainly due to the varying width of the muscular insertion in the hyoid bone.