Schindler H J, Türp J C, Blaser R, Lenz J
Federal Research Center for Nutrition, Karlsruhe, Germany.
J Oral Rehabil. 2005 Aug;32(8):552-63. doi: 10.1111/j.1365-2842.2005.01466.x.
The aim of this study was to investigate (i) whether the masseter muscle shows differential activation under experimental conditions which simulate force generation during clenching and grinding activities; and (ii) whether there are (a) preferentially active muscle regions or (b) force directions which show enhanced muscle activation. To answer these questions, the electromyographic (EMG) activity of the right masseter muscle was recorded with five intramuscular electrodes placed in two deep muscle areas and in three surface regions. Intraoral force transfer and force measurement were achieved by a central bearing pin device equipped with three strain gauges (SG). The activity distribution in the muscle was recorded in four different mandibular positions (central, left, right, anterior). In each position, maximum voluntary contraction (MVC) was exerted in vertical, posterior, anterior, medial and lateral directions. The investigated muscle regions showed different amount of EMG activity. The relative intensity of the activation, with respect to other regions, changed depending on the task. In other words, the muscle regions demonstrated heterogeneous changes of the EMG pattern for the various motor tasks. The resultant force vectors demonstrated similar amounts in all horizontal bite directions. Protrusive force directions revealed the highest relative activation of the masseter muscle. The posterior deep muscle region seemed to be the most active compartment during the different motor tasks. The results indicate a heterogeneous activation of the masseter muscle under test conditions simulating force generation during clenching and grinding. Protrusively directed bite forces were accompanied by the highest activation in the muscle, with the posterior deep region as the most active area.
(i)在模拟紧咬和磨牙活动中产生力的实验条件下,咬肌是否表现出不同的激活情况;以及(ii)是否存在(a)优先活跃的肌肉区域或(b)表现出增强肌肉激活的力的方向。为了回答这些问题,通过将五个肌内电极放置在两个深部肌肉区域和三个表面区域来记录右侧咬肌的肌电图(EMG)活动。通过配备三个应变片(SG)的中央支承销装置实现口内力传递和力测量。在四个不同的下颌位置(正中、左侧、右侧、前位)记录肌肉中的活动分布。在每个位置,在垂直、后方、前方、内侧和外侧方向施加最大自主收缩(MVC)。所研究的肌肉区域表现出不同程度的EMG活动。相对于其他区域,激活的相对强度根据任务而变化。换句话说,肌肉区域在各种运动任务中表现出EMG模式的异质性变化。在所有水平咬合方向上,合力矢量显示出相似的量。前伸力方向显示咬肌的相对激活最高。在不同的运动任务中,后部深部肌肉区域似乎是最活跃的部分。结果表明,在模拟紧咬和磨牙活动中产生力的测试条件下,咬肌存在异质性激活。前伸方向的咬力伴随着肌肉中最高的激活,后部深部区域是最活跃的区域。