Effect of head position and mouth opening on the ability of swallowing

13名受试者被要求一次吞下10毫升注入口腔的水。吞咽后，抽吸残馀口内水，测量其体积。测试过程中还记录了舌骨上(SH)肌的肌电(EMG)。检测SH肌电活动持续时间和SH肌电波幅。分别在3种头位(中立位、伸缩位和屈曲位)和4种张口方式(切缝间距分别为0 mm、20 mm、30 mm和40 mm)下进行吞水试验。受试者的嘴张得越大，吞咽后留在嘴里的水就越多。伸展位的残余水量比中立位和屈曲位的多。随着张口度的增加，SH-EMG的峰值降低。伸展位SH肌活动持续时间长于中立位和屈曲位。

Thirteen subjects were asked to swallow 10 ml of water that was injected into the mouth in a single attempt. After swallowing, the residual intraoral water was suctioned and its volume was measured. An electromyogram (EMG) of the suprahyoid (SH) muscles was also recorded during the test. The duration of SH muscle activity and peak amplitude of SH EMG were examined. The water swallowing test was performed under 3 head positions (neutral, extended and flexed) and 4 mouth opening patterns (interincisal distances of 0 mm, 20 mm, 30 mm and 40 mm). The wider the subject opened the mouth, the more water remained in the mouth after swallowing. The residual volume of water was more in the extended position compared with that in the neutral and flexed positions. Peak amplitude of SH EMG decreased with mouth opening. Duration of SH muscle activity was longer in the extended position than in the neutral and flexed positions.