The meridian branches of the twelve meridians stem from the twelve meridians, run deep into the trunk, associate with the viscera and the branches of the meridians in external and internal relation. The meridian branches are actually the regular meridians that run along other routes. As to the nature, the meridian branches stemming from the twelve meridians pertain to the aspect of the twelve meridians. In distribution, the meridian branches run deep into the body, associate with the meridians in external and internal relation, indicating that the distribution of the meridian branches is centripetal.
The running of the branches of the twelve meridians is marked by "stemming, entering, outthrusting and combination".
"Stemming" means that the meridian branches stem from the areas below the knees and elbows, usually the meridian branches run parallel to or together with the meridians in external and internal relation; “entering” means that the meridian branches enter the body and usually associate with the viscera in external and internal relation, the branches of the three yang meridians of the foot also associate with the heart; “outthrusting” means that the meridian branches come out to run in the superficial areas over the head and neck; "combination" means that the branches of the yin meridians combine with the yang meridians that they are in internal and external relation with, while the branches of the yang meridians combine with the meridians that they stem from.
In this way, the three yin and three yang meridians of the hand and foot constitute “six combinations”. By means of “stemming, entering, outthrusting and combination”, the branches of the twelve meridians further strengthen the meridians in external and internal relation, especially the association of the meridians with the viscera in external and internal relation. With such activities, the meridian branches also widen the distribution of the meridians, reinforce the association of the twelve meridians with the whole body, and enlarge the indication of the acupoints.