A superior hypogastric plexus block is a common treatment for people who suffer from tailbone, lower abdominal, or pelvic pain. The sympathetic nervous system includes the heart muscles, but it starts at the spinal column and extends to all smooth muscles and glands within the body. These nerves respond to any unexpected changes in the body that might be physical or environmental by transmitting signals that regulate essential biological processes. Even involuntary movements are regulated by nerves in this system. Patients who have persistent pelvic pain are typically treated with pain relievers and injections. If this form of treatment is not effective or causes harmful side effects, a physician may recommend a superior hypogastric plexus block.