Before modern medicine, in which treatment's with certain ethical therapies and medication, most patients with mental illness where placed in institutions no matter how severe, and were forced to go through unethical therapies such as electroshock or lobotomies.
I believe it is the nervous system but I'm not 100% sure
The link between the two is that they both can cause headaches and sores from the body. Since anxiety affects the body mentally it can also affect it physically too.
Power relations change over time and well we all have different gender so you really cant hit one or the other