Han Y, Wang J, Fischman D A, Biller H F, Sanders I
Department of Otolaryngology, The Mount Sinai Medical Center, New York, New York 10029, USA.
Anat Rec. 1999 Oct 1;256(2):146-57. doi: 10.1002/(SICI)1097-0185(19991001)256:2<146::AID-AR5>3.0.CO;2-8.
Most of the sounds of human speech are produced by vibration of the vocal folds, yet the biomechanics and control of these vibrations are poorly understood. In this study the muscle within the vocal fold, the thyroarytenoid muscle (TA), was examined for the presence and distribution of slow tonic muscle fibers (STF), a rare muscle fiber type with unique contraction properties. Nine human TAs were frozen and serially sectioned in the frontal plane. The presence and distribution pattern of STF in each TA were examined by immunofluorescence microscopy using the monoclonal antibodies (mAb) ALD-19 and ALD-58 which react with the slow tonic myosin heavy chain (MyHC) isoform. In addition, TA muscle samples from adjacent frozen sections were also examined for slow tonic MyHC isoform by electrophoretic immunoblotting. STF were detected in all nine TAs and the presence of slow tonic MyHC isoform was confirmed in the immunoblots. The STF were distributed predominantly in the medial aspect of the TA, a distinct muscle compartment called the vocalis which is the vibrating part of the vocal fold. STF do not contract with a twitch like most muscle fibers, instead, their contractions are prolonged, stable, precisely controlled, and fatigue resistant. The human voice is characterized by a stable sound with a wide frequency spectrum that can be precisely modulated and the STF may contribute to this ability. At present, the evidence suggests that STF are not presented in the vocal folds of other mammals (including other primates), therefore STF may be a unique human specialization for speech.
人类语音的大部分声音是由声带振动产生的，然而这些振动的生物力学和控制机制却鲜为人知。在本研究中，对声带内的肌肉——甲杓肌（TA）进行了检查，以确定慢张力肌纤维（STF）的存在和分布情况。慢张力肌纤维是一种罕见的肌纤维类型，具有独特的收缩特性。研究人员将9条人类甲杓肌冷冻，并在额平面上进行连续切片。使用与慢张力肌球蛋白重链（MyHC）同工型发生反应的单克隆抗体（mAb）ALD - 19和ALD - 58，通过免疫荧光显微镜检查每条甲杓肌中慢张力肌纤维的存在和分布模式。此外，还通过电泳免疫印迹法对相邻冷冻切片的甲杓肌样本进行了慢张力MyHC同工型检测。在所有9条甲杓肌中均检测到了慢张力肌纤维，免疫印迹证实了慢张力MyHC同工型的存在。慢张力肌纤维主要分布在甲杓肌的内侧，这是一个名为声带肌的独特肌肉隔室，是声带的振动部分。与大多数肌纤维不同，慢张力肌纤维不会产生抽搐式收缩，相反，它们的收缩持续时间长、稳定、精确可控且抗疲劳。人类的声音具有稳定的音色和宽广的频谱，能够进行精确调制，慢张力肌纤维可能有助于实现这种能力。目前，有证据表明其他哺乳动物（包括其他灵长类动物）的声带中不存在慢张力肌纤维，因此慢张力肌纤维可能是人类在语音方面特有的一种适应性特征。
