《黄帝内经·灵枢·邪客》
以上的八虚位置，都是关节屈伸的枢纽，也是真气和血络通行的要处。
凡此八虚者，皆机关之室，真气之所过，血络之所游。
The above eight hollow positions are all the pivot points of joint flexion and extension, and they are also the key points for the circulation of true qi and blood vessels.