How Acupuncture Works
The Ancient Explanation
China's first dynasty was founded after Yu the Great devised a way to create irrigation channels to control flooding and manage crops.
This ability to manage flow within channels to avert disaster and promote health became the blueprint for the Chinese understanding of human health as well.
The basic idea is that if a river has proper and regulated flow, then it remains clean, it does not flood, and all parts of the riverbank are enriched. If, conversely, flow becomes compromised, then there can be accumulation of debris, local flooding, and areas downstream robbed of proper nourishment.
The acupuncturists job is to gauge the state of flow within the channels, to determine if there are areas where the natural flow of qi (which can be thought of as the sum total of all the materials and messages that are transported throughout the body for optimal health) has stagnated, and to place needles in strategic locations in order to regulate that flow.
The Modern Explanation
The acupuncture channels follow important neurovascular pathways, and have confluence with important planes in the fascia as well. The points themselves are often located in areas where there are significant neurovascular bundles.
This means that the subtle stimulation of an acupuncture needle directly influences not only the local tissue but also the blood vessels, the peripheral nervous system, and the fascia.
Points also have non-local and non-linear effects that have been measured, such as influencing regions of the brain, increasing secretion of the hydrochloric acid, increasing vagal tone, regulating blood pressure, promoting release of gasotransmitters like nitrous oxide, etc.
These points can thus stimulate circulation, reduce inflammation, promote parasympathetic nervous system activation, and regulate many of the body's physiological functions.