PROPERTIES OF MOTOR UNITS IN HUMAN MANDIBULAR MUSCLES

人类下颌肌的某些收缩特性是 未知。包括舌骨、舌骨、舌骨的痉挛收缩时间， 两个翼骨外侧的头部，和特征的长度-张力 这些肌肉的关系，以及咬肌、颞肌、内侧肌 翼状肌和前二腹肌。单动车组技术 肌电图术、力传导和尖峰触发的平均 应用于人体活体测定(1)特征 抽动收缩时间、抽动张力与招募的关系 这些肌肉中单个运动单位的阈值；(2)影响 以及随之而来的肌肉长度的变化，对运动单位抽搐 收缩次数和抽动张力；以及(3)运动的均质性程度。 具有相似“尺寸”的电机单元的收缩特性 每块肌肉的不同区域。 众所周知，整个肌肉的收缩特性是 从他们的发动机性能的平均值中合理地预测得很好 单位。因此，要获得的数据将提供第一表征 人类下颌肌的特性限制了他们的 产生和调节力的能力。据推测，物业 这样也会限制个体的功能和时间 在执行和控制复合体过程中这些肌肉的协调 在说话和咀嚼时发生的下颌的运动。因此， 描述这些属性的数据对于 人体肌肉骨骼这一部分的通用生物力学模型 系统。这样的模型在调查这两个问题时特别有用 正常和无序的言语产生，可能被证明在 预测牙科和颅面的某些功能后果 影响下颌肌肉的外科手术。

Certain contractile properties of the human mandibular muscles are unknown. These include twitch contraction time for geniohyoid, mylohyoid, and both heads of lateral pterygoid, and the characteristic length-tension relations for those muscles, as well as for masseter, temporalis, medial pterygoid, and anterior digastric. The techniques of single-motor-unit electromyography, force transduction, and spike-triggered averaging will be applied to human subjects to determine in vivo (1) the characterisitc relations between twitch contraction time, twitch tension, and recruitment threshold for single motor units in each of these muscles; (2) the effects of gape, and the attendant changes in muscle length, on motor unit twitch contraction times and twitch tensions; and (3) the extent of homogeneity of contractile properties of motor units having similar "sizes" but lying in different regions of each muscle. It is well known that contractile properties of whole muscles are reasonably well-predicted from averages of properties of their motor units. Thus, the data to be obtained will provide a first characterization of properties of the human mandibular muscles which constrain their capabilities for generating and modulating force. Presumably, properties such as these will also constrain the individual functions and temporal coordination of these muscles during execution and control of complex movements of the mandible which occur in speech and mastication. Thus, data describing these properties are of fundamental importance for a general biomechanical model of this portion of the human musculoskeletal system. Such a model would be particularly useful in investigation of both normal and disordered speech production, and may prove of equal value in predicting certain functional consequences of dental and craniofacial surgical procedures which affect the mandibular muscles.