What is the meridian system? Does it really exist?
There have been a great many efforts by modern scientists to “find” the TCM meridian system using modern diagnostic tools such as MRI. None of these has been able to point to a single system, such as the nervous system, or circulatory system, which has led many skeptics to shout “Aha! Its all a hoax! Millions of people over thousands of years were simply affected by the placebo effect!” However, this placebo theory falls apart when examining how acupuncture has been effectively used on animals, who have no preconceptions. Furthermore, as my first year clinical supervisor used to say- if a relatively simple intervention of inserting a thin sterile needle relieves pain versus having to have surgery, take strong pharmaceuticals with serious side effects, or live in chronic pain, who really cares if it's “just a placebo?”
I, as a university trained scientist and decidedly non-woo woo former acupuncture/TCM skeptic myself, have a different perception of the mechanistic model of the meridian system.
I personally think that the meridian pathways are carried by the integration of the following very tangible systems of the body: fascial/connective tissue; nervous system; circulatory system, lymphatic drainage system and musculoskeletal system, all tied together at the embyrological state of development. I will be doing a deeper dive into my personal theory in an upcoming blog on this subject.