Vinkka-Puhakka H, Kean M R, Heap S W
Institute of Dentistry, University of Turku, Finland.
J Anat. 1989 Oct;166:121-33.
Real-time ultrasound with a high frequency probe is used to image the circumoral musculature with the lips relaxed and contracted. The ultrasonic images show that muscle tissue makes up only a part of the total thickness of the lip, and varies among individuals in shape, transonicity (clearness) and thickness. The muscle layer in the upper lip is sandwiched between layers of facial and lingual connective tissue, while the muscle image in the lower lip lies close to the lingual surface. In a relaxed state the muscle layer in the lower lip is significantly thicker than that in the upper lip, and a mean difference also occurs in contraction, but to a considerably lesser degree. Thus the upper lip muscle appears to increase in thickness during contraction relatively more than does that of the lower lip. Furthermore, the contraction in the upper lip seems to occur fairly uniformly along the lip from left to right. The muscular changes in the lower lip are more complex, even though embryologically complexity is ascribed properly to the upper lip. In the lower lip contraction seems to occur in the lateral parts and in the mentalis muscle, but in the midline the orbicularis oris muscle remains quite inactive. More complex arrangements are essential merely to ensure support of the lower lip against gravity.
使用高频探头的实时超声来对唇部放松和收缩状态下的口周肌肉组织进行成像。超声图像显示，肌肉组织仅占唇部总厚度的一部分，且在个体之间形状、透声性（清晰度）和厚度各异。上唇的肌肉层夹在面部和舌部结缔组织层之间，而下唇的肌肉图像靠近舌面。在放松状态下，下唇的肌肉层明显比上唇厚，收缩时也存在平均差异，但程度要小得多。因此，上唇肌肉在收缩时厚度增加相对比下唇更明显。此外，上唇的收缩似乎从左到右沿着唇部相当均匀地发生。下唇的肌肉变化更为复杂，尽管从胚胎学角度来看，上唇的复杂性是合理的。在下唇，收缩似乎发生在外侧部分和颏肌，但在中线处口轮匝肌仍然相当不活跃。更复杂的结构仅仅是为了确保下唇能抵抗重力的支撑。
