retraction of dental arch

• 牙弓后缩

retraction of dental arch的用法和样例：

例句

1. The narrowed segment called coarctation can occur anywhere in the aorta, but is most likely to happen in the segment just after the aortic arch.
   狭窄的部分称为缩窄，可发生在主动脉的任何地方，但是最容易发生在紧接主动脉弓后的部分。