Single motor units' study on the role of the human lateral pterygoid muscle in the generation of horizontal mandibular force

目的是验证人外侧翼状肌（LP）的下头（IH）参与水平等距下颌骨力的产生和精细控制的假设。在8名参与者中，单运动单元活动（smu）记录了IHLP在对侧（CL），同侧（IL），突出(P)方向和两个中间方向（对侧-突出（CL-P），同侧-突出（IL-P））向目标产生这种力时的单侧运动单元活动（smu）。从牙间位置开5- 8mm处的等距力通过一根杆连接在上牙上的换能器施加（通过一根杆连接在上牙上），并沿一个方向连接在下牙上的水平等距力。参与者在视频屏幕上跟踪一个目标，在400吕震波（3.92吕震波）和800吕震波（7.84吕震波）之间，每100吕震波（0.98牛顿）需要5秒的时间。在等距CL收缩时，我们可以可靠地区分出21个smu。21只IHLP smu的平均射速随用力的增加而显著增加（p<0.0001）。在CL中鉴定出三种类型的smu:(a) tonic (t-unit, 10/21, 48%), (b) intermediate （I-unit, 4/21, 19%）和(c) phase或主要phase （P-unit, 7/21, 83%）。21个IHLP smu的平均射速也受方向的影响，其中以CL的活性最高，随着方向向il的转移而逐渐降低，表明IHLP参与了不同水平方向下颌骨力的产生和精细控制。

The aim was to test the hypothesis that the inferior head (IH) of the human lateral pterygoid muscle (LP) is involved in the generation and fine control of horizontal isometric mandibular force. In eight participants, single motor units' activity (SMUs) was recorded from IHLP unilaterally during the generation such forces to a target in contralateral (CL), ipsilateral (IL), protrusive (P) directions and in two intermediate directions (contralateral-protrusive (CL-P), ipsilateral-protrusive (IL-P)). Isometric force at 5-8 mm open from the intercuspul position was exerted on a transducer (attached by a bar to the upper teeth) by a rod attached to the lower teeth of horizontal isometric mandibular force in a direction. Participants tracked a target on a video screen that required 5-s holding periods at each 100 gwt (0.98 N) between 400 gwt (3.92 N) and 800 gwt (7.84 N).We could reliably discriminate 21 SMUs during isometric CL contraction. The mean firing rates of 21 IHLP SMUs significantly increased with force (p<0.0001). Three patterns of SMUs were identified at CL: (a) tonic (t-unit; 10/21, 48%), (b) intermediate (I-unit; 4/21, 19%) and (c) phasic or predominantly phasic (P-unit; 7/21, 83%). The mean firing rates of 21 IHLP SMUs were also affected by direction, with the highest activity being CL, and graded decreases occurring as the direction shifted to IL.The data suggest that the IHLP is involved in the creation and fine control of mandibular forces in different horizontal directions.