《黄帝内经·灵枢·终始》
寸口脉大于人迎脉四倍，且其脉象大而且快的，是六阴经的脉气偏盛到了极点而盈溢于内的表现，这种情况就叫做溢阴；出现溢阴时，由于阴气偏盛至极，就会使阳气不能内入，而出现阴气不能与阳气相交的情况，所以此时的情形就称为内关。
脉口四盛，且大且数者，名曰溢阴。溢阴为内关，内关不通，死不治。人迎与太阴脉口俱盛四倍以上，名曰关格。
If the Cunkou pulse is greater than the Renying pulse by a factor of four, and the pulse is large and rapid, it indicates that the pulse qi of the six yin channels is excessively strong and overflowing inwards. This condition is called overflowing yin; when overflowing yin occurs, because the yin qi is excessively strong, it will prevent the yang qi from entering, resulting in a situation where the yin qi cannot interact with the yang qi. Therefore, this situation is called internal blocking.