Establish imaging diagnostic criteria of masticatory muscle tendon-aponeurosis hyperplasia

为建立咀嚼肌腱膜增生症(HyTAM)的影像诊断标准：1)对正常人(对照组)和咀嚼肌腱膜增生症患者(HyTAM组)的咀嚼肌腱和腱膜进行CT分析；2)分析下颌运动、咬合和最大咬合时的肌肉活动水平。1)根据CT图像分析结果，将咬肌内的肌腱和腱膜分成4种类型：I型，咬肌前缘有单一细长的肌腱；II型，咬肌前缘有一条从颧突到下颌咬肌脊的单一肌腱；III型，咬肌内有从颧突到下颌咬肌脊的多条肌腱；对照组咬肌的I、II、III、IV型分别为163、14、19、4侧，HyTAM组分别为0、1、31、2侧。2)在下颌运动方面，HyTAM组的最大张口量明显小于对照组，但前移量和侧移量差异无统计学意义。HyTAM组最大咬合力明显大于对照组。在最大咬合时，HyTAM组的颞肌和咬肌的肌肉活动水平显著高于对照组，但在颞肌和咬肌的活动水平比率上没有显著差异。提示分析下颌运动、咬合和最大咬合时咬肌肌腱、腱膜和咀嚼肌活动水平是有用的。

To establish imaging diagnostic criteria of masticatory muscle tendon-aponeurosis hyperplasia(HyTAM): 1) the tendon and aponeurosis of the masseter were analyzed involving normal subjects(control group) and HyTAM patients(HyTAM group) employing CT, and then 2) muscle activity levels during mandibular movement, occlusion, and maximum voluntary clenching were analyzed. 1) The human tendon and aponeurosis in the masseter were classified into the following 4 types based on the findings of CT image analysis : Type I, a single thin tendon was present at the anterior margin of the masseter ; type II, a single, tendon continuous from the zygomatic process to the mandibular masseter ridge was present at the anterior margin of the masseter ; type III, multiple tendons continuous from the zygomatic process to the mandibular masseter ridge were present in the masseter ; and type IV, others. Types I, II, III, and IV were noted on 163, 14, 19, and 4 sides of the masseter in the control group, respectively, and 0, 1, 31, and 2 sides in the HyTAM group, respectively. 2) Regarding mandibular movement, the maximum mouth opening was significantly smaller in the HyTAM than in the control group, but no significant differences were noted in the amount of anterior or lateral movement. The occlusal force of maximum clenching was significantly greater in the HyTAM than in the control group. The muscle activity levels of the temporal and masseter muscles while maximum clenching were significantly greater in the HyTAM than in the control group, but no significant difference was noted in the temporal-to-masseter muscle activity level ratio. It was suggested that the analyzing of the tendon and aponeurosis of the masseter and masticatory muscle activity levels during mandibular movement, occlusion, and maximum voluntary clenching were useful.