運用超音波對顏面與喉部肌群之觀測分析

背景：口面部與頸部肌肉在語音產出過程中扮演重要角色。雖然過去多數研究著重於舌頭功能，但對其它肌群如咬肌與二腹肌前腹的結構與功能變化探討仍有限。隨著超音波影像技術的進步，現今可即時、非侵入性地觀察肌肉變化，對於語音相關的臨床評估具有實用價值。目的：本研究旨在建立健康台灣成人（20至50歲）在靜止與動作狀態（張口與發音/a/與/i/）下，咬肌與二腹肌前腹之厚度與截面積（CSA）之常模資料。方法：招募31位健康受試者，透過12.5 MHz線性探頭於雙側進行超音波掃描，分別在靜止、張口及發音/a/與/i/的情境下測量咬肌與二腹肌前腹的厚度與CSA，各狀態重複量測三次取平均值。使用SPSS進行成對樣本與獨立樣本t檢定及BMI相關性分析。結果：咬肌與二腹肌前腹在張口與發音/a/時皆呈現顯著增厚，且男性肌肉尺寸顯著大於女性。相對地，在發音/i/時，肌肉厚度與CSA顯著下降或無顯著改變。BMI與肌肉靜止狀態下的厚度（尤其為咬肌與左側二腹肌前腹CSA）呈現正相關。結論：不同發音任務會引發肌肉的差異性變化，/a/相較/i/引發較顯著的肌肉參與。研究結果揭示性別與BMI亦會影響肌肉結構差異，所建立之常模資料將有助於未來語音相關的臨床肌肉功能評估與研究應用。

Background: Orofacial and neck muscles play critical roles in speech production. While prior research has largely focused on the tongue, less is known about structural and functional variations in other muscles including the masseter and anterior belly of the digastric. Advancements in ultrasound imaging provide a noninvasive method to assess muscle morphology in real time, offering clinical value for evaluating dynamic muscle changes during speech-related tasks.Objective: This study aims to establish normative data for the thickness and cross-sectional area (CSA) of the masseter and anterior belly of the digastric muscles in healthy Taiwanese adults aged 20 to 50 years, across resting and dynamic states, including jaw opening and phonation of vowels /a/ and /i/.Methods: 31 healthy participants underwent bilateral ultrasound measurements of the masseter and anterior belly of digastric muscles at rest, during mouth opening, and while producing /a/ and /i/. A linear 12.5 MHz transducer captured three repeated measurements per condition. Statistical analyses, including paired and independent t-tests and Pearson correlations with body mass index, were executed via the Statistical Package for the Social Sciences (SPSS).Results: Both muscles showed significant thickness increases during jaw opening and vowel /a/ production, with males exhibiting greater muscle dimensions than females. In contrast, muscle thickness and CSA decreased or remained unchanged during vowel /i/. Positive correlations were found between BMI and resting muscle thickness, particularly for the masseter and left CSA of anterior belly of the digastric.Conclusion: The results demonstrate task-specific and sex-related differences in orofacial and suprahyoid muscle morphology. Vowel-specific demands influence muscle activation, with /a/ eliciting greater structural engagement than /i/. These normative values may serve as a reference for future studies and support ultrasound’s clinical utility in functional muscle assessment related to speech.