Kuna S T, Vanoye C R
Department of Internal Medicine, University of Texas Medical Branch, Galveston 77555-0561.
Am J Respir Crit Care Med. 1994 Sep;150(3):729-34. doi: 10.1164/ajrccm.150.3.8087344.
Previous investigators have reported that transient forced expiration is accompanied by abduction of the vocal cords. To further investigate the laryngeal response during voluntary forced vital capacity maneuvers, intramuscular electromyographic recordings were obtained in 25 normal adult humans from three intrinsic laryngeal muscles: the posterior cricoarytenoid (PCA), a vocal cord abductor, and the thyroarytenoid (TA) and arytenoideus (AR), both vocal cord adductors. All three muscles exhibited sustained activation throughout most of forced expiration from total lung capacity. Forced inspiration from residual volume was associated with a further increase in PCA activity and a marked decrease in adductor muscle activity. To determine the net effect of these electromyographic changes on vocal cord position, simultaneous fiberoptic recordings of vocal cord movement were obtained in five of the subjects. The angle formed by the vocal cords at the anterior commissure was used to assess glottic aperture size. Glottic angle progressively decreased from peak expiratory flow to the end of forced expiration. The angle was 56 +/- 13 degrees (SD) at peak expiratory flow, 34 +/- 4 degrees after forced expiration of 90% of the vital capacity, and 7 +/- 7 degrees at end-expiration. The results indicate that forced expiration is associated with marked activation of not only the PCA but also laryngeal adductor muscles. During forced expiration, the glottis does not decrease below its size during quiet breathing until exhalation of about 75% of forced vital capacity.
先前的研究人员报告说，短暂的用力呼气伴随着声带外展。为了进一步研究自主用力肺活量动作期间的喉部反应，对25名正常成年人的三块喉内肌进行了肌内肌电图记录：后环杓肌（PCA），一种声带外展肌，以及甲杓肌（TA）和杓肌（AR），两者均为声带内收肌。在从肺总量开始的大部分用力呼气过程中，所有三块肌肉都表现出持续激活。从残气量开始的用力吸气与PCA活动的进一步增加和内收肌活动的显著减少有关。为了确定这些肌电图变化对声带位置的净效应，在5名受试者中同时进行了声带运动的纤维光学记录。用声带在前连合处形成的角度来评估声门裂孔大小。声门角度从呼气峰值流量到用力呼气结束逐渐减小。在呼气峰值流量时角度为56±13度（标准差），在用力呼出肺活量的90%后为34±4度，在呼气末为7±7度。结果表明，用力呼气不仅与PCA的显著激活有关，还与喉内收肌有关。在用力呼气过程中，直到呼出约75%的用力肺活量时，声门才会减小到安静呼吸时的大小以下。
