PDF(Pubmed)
Abstract：
Levator palpebrae superioris muscle (LPSM) and facial muscles comprise fast-twitch fibers (FTFs) and slow-twitch fibers (STFs) but lack muscle spindles required to contract STFs reflexively. Voluntary contractions and microsaccades of FTFs in LPSM stretch mechanoreceptors in superior tarsal muscle (STM) to induce phasic contractions of STFs in LPSM and frontalis muscle via mesencephalic trigeminal nucleus (MTN). They also induce prolonged contractions of STFs in bilateral frontalis and orbital orbicularis oculi muscles and physiological arousal via MTN and rostral locus coeruleus (LC). We hypothesized that stretching of mechanoreceptors in STM also induces prolonged contractions of STFs in other facial expression muscles (FEMs) via rostral LC. To verify this hypothesis, we reported a case series of abnormal contractions of FEMs due to aponeurosis disinsertion and disordered mechanoreceptor stretching. The first and second cases, which showed unilaterally and bilaterally sensitized mechanoreceptors, respectively, recorded increased prolonged contractions of ipsilateral and bilateral grimacing muscles, respectively. The third and fourth cases with asymmetrically and bilaterally desensitized mechanoreceptors experienced asymmetrically and bilaterally decreased prolonged contractions of grimacing and smiling muscles, respectively. Preoperatively and after surgery was performed to adjust mechanoreceptor stretching and reinsert aponeuroses into tarsi, we evaluated prolonged contractions of grimacing and smiling muscles during primary gazing and facial expression movements. Surgery satisfactorily cured abnormal prolonged contractions of grimacing and smiling muscles. Stretching of mechanoreceptors in STM by microsaccades or voluntary contractions of FTFs in LPSM might activate rostral LC via MTN, which tonically or phasically stimulates FEM motor neurons to reflexively contract their STFs, respectively.
摘要：
上睑提肌（LPSM）和面部肌肉包括快速抽搐纤维（FTF）和缓慢抽搐纤维（STF），但缺乏反射收缩STF所需的肌肉纺锤。LPSM舒展力器中FTFs的自愿性收缩和微小扫视通过中脑三叉神经核（MTN）诱导LPSM和额肌STFs的阶段性收缩。它们还通过MTN和头端蓝斑（LC）诱导双侧额肌和眶眼轮匝肌STF的长时间收缩和生理唤醒。我们假设STM中机械感受器的拉伸也会通过头端LC诱导其他面部表情肌（FEM）中STF的长时间收缩。为了验证这个假设，我们报告了一系列病例，这些病例是由于腱膜脱出和机械感受器伸展紊乱引起的FEM异常收缩。第一种和第二种情况，显示单侧和双侧敏感的机械受体，分别,记录的同侧和双侧做鬼脸肌肉的长时间收缩增加，分别。第三例和第四例不对称和双侧脱敏的机械感受器经历了不对称和双侧减少的长期收缩，分别。术前和术后进行调整机械感受器拉伸并将腱膜重新插入tarsi，我们评估了在主要注视和面部表情运动期间，做鬼脸和微笑的肌肉的长时间收缩。手术可以令人满意地治愈做鬼脸和微笑肌肉的异常长时间收缩。通过微扫视或LPSM中FTFs的自愿收缩来拉伸STM中的机械受体可能会通过MTN激活延髓LC，音调或相位刺激FEM运动神经元反射性收缩其STF，分别。
