子午流注用語(yǔ)。指陽(yáng)經(jīng)開(kāi)輸穴的同時(shí),必須同開(kāi)原穴?!氨尽?,指本日的值日經(jīng);“原”,指值日經(jīng)的原穴。如甲日甲戌時(shí)開(kāi)膽經(jīng)(值日經(jīng))井穴足竅陰,丙子時(shí)開(kāi)小腸經(jīng)滎穴前谷,戊寅時(shí)開(kāi)胃經(jīng)輸穴陷谷,同時(shí)開(kāi)膽經(jīng)的原穴丘墟,此為返本還原。《大全》:“經(jīng)中必有返本還原者,乃十二經(jīng)出入之門(mén)戶也?!?/p>