DU20 BǎiHuì  to DU19 HòuDǐng corresponds to the upper and lower segments of the thoracic vertebrae, and DU19 HòuDǐng to DU18 QiángJiān corresponds to the lumbar spine.
百會至後頂對應胸椎的上下段，後頂至強間則對應於腰椎。

Reference:

Dongshi Qixue 董式奇穴實用手冊，邱雅昌編著，人民衛生出版社，北京2019

針灸經絡穴位速記手冊，主編黃泳、王升旭、陳俊琦．廣東科技出版社，廣州2010