This region of the brainstem and upper spinal cord is really important for our perception of our head, neck, and face. This is especially true in terms of pain.
Pain experienced in the head/neck/face have strong and fast connections to areas of the brain associated with autonomic and limbic consequences. That means that pain in these areas have a greater probability to have effects on emotions and organ function, which may explain why nausea and heightened distress and suffering are tied to chronic pain in these regions.
The reasoning is that these areas can have strong direct connections to pain modulating areas of the brain. They also have been shown to have strong effects on blood flow patterns in the arteries of the brain in animal models.
For practical purposes, we have to consider that pain in one part of the head/neck/face may be coming from another area with similar neurological origins. We should also consider that if someone has pain in one region, that we can treat another region to modulate the pain response as the actual source of injury may be too sensitized and makes the patient feel worse.
The important takeaway is that we don’t necessarily need to treat the exact site of pain in order to get a good outcome
Pain is tricky and can fool us, but an understanding of neurology can sometimes help us work around it.