Do you know someone who has trouble with swallowing, dry mouth, irregular heart rate, sense of taste, memory or emotions?
The neurology of the upper cervical spine is remarkable. The brainstem consists of mesencephalon, pons and medulla. The medulla contains the intermedius nucleus (InM), which has receptors for head and neck posture. Changes in head and neck posture/position (adjustments or injuries) will be sent to the InM, which will then send information to the nucleus tractus solitarius (NTS). The NTS transfers information to the dorsal motor nucleus of cranial nerve X (vagus nerve) which makes changes to heart rate, lung function, gastro-intestinal function, mouth/tongue function, and taste buds. Do you have diarrhea or constipation? Do you have an irregular heartbeat? Rapid heart rate? Do you have trouble breathing or swallowing or speaking?
The NTS also sends information to the cingulate gyrus, which is part of the limbic system and has an important role in emotional forming and processing, learning and memory. Proper function helps you learn more effectively!
The InM has a very important role in the involuntary nervous system (autonomic nervous system) which consists of both sympathetic and parasympathetic. See my post on the autonomic nervous system.
For reference, you can also see the PubMed article on the InM here.
As you can see, the effects of changes to the upper cervical spine are far beyond musculoskeletal. There is also a nerve pathway showing inhibition of pain. That is why people have been going to chiropractors for over a hundred years for pain relief. Additionally, people have been going to chiropractors for over a hundred years for bodily function improvements as well, long before the reason for the improvement was known.