Shall M S, Goldberg S J
Department of Physical Therapy, Medical College of Virginia/Virginia Commonwealth University, Richmond, USA.
Muscle Nerve. 1995 Sep;18(9):948-55. doi: 10.1002/mus.880180905.
Stimulation of 41 single, abducens nucleus motoneurons in the cat evoked electromyographic (EMG) and contractile responses in the ipsilateral lateral rectus muscle. Separate, bipolar, fine wire EMG recording electrodes in the global and orbital muscle layers showed that 22 muscle units were confined to the global layer, 8 to the orbital layer, and 11 units were contained in both ("bilayer") muscle layers. "Bilayer" units demonstrated significantly greater twitch (P < or = 0.002) and maximum tetanic (P < or = 0.001) tensions as well as faster fusion frequencies (P < or = 0.022) than either global or orbital units. "Bilayer" units also showed the lowest average kt values (the slope of the linear relationship between motoneuron stimulation frequency and isometric tetanic tension). "Bilayer" units were predominantly fast fatigable (FF). Global units displayed all muscle unit types including all the nontwitch (NT) units. Orbital units were identified as slow fatigable (SF) and fast fatigue resistant (FR).
刺激猫的41个单个展神经核运动神经元，可诱发同侧外直肌的肌电图（EMG）和收缩反应。在眼球外肌层和眶肌层中分别使用双极细钢丝EMG记录电极，结果显示，22个肌肉单位局限于眼球外肌层，8个局限于眶肌层，11个单位同时存在于两层（“双层”）肌肉层中。与眼球外肌层或眶肌层单位相比，“双层”单位表现出明显更大的抽搐张力（P≤0.002）和最大强直张力（P≤0.001），以及更快的融合频率（P≤0.022）。“双层”单位还显示出最低的平均kt值（运动神经元刺激频率与等长强直张力之间线性关系的斜率）。“双层”单位主要是快速易疲劳型（FF）。眼球外肌层单位表现出所有类型的肌肉单位，包括所有非抽搐型（NT）单位。眶肌层单位被确定为慢速易疲劳型（SF）和快速抗疲劳型（FR）。
