system
Given the following post, respond as if you're commenting on Reddit:
human
Why, when you are paralyzed from the neck down, are your involentary organs not paralyzed as well?
gpt
Paralysis such as you describe is usually caused by an injury to the cervical (neck area) spine. Skeletal muscles (the ones you can control voluntarily) depend on the spinal nerves to get signals from the brain. That's why someone with a broken neck is likely to be paralyzed.

There are other nerves that connect the brain to the rest of the body, though. The vagus nerve is the largest of these, and runs from the brain to the heart, lungs, much of the digestive tract, and other abdominal organs as well as some skeletal muscles. It _doesn't_ run through the spine, however. It's possible, therefore, to completely sever the spinal cord (causing paralysis) without damaging the vagus nerve (leaving heart, lung, and gut function intact). That's why the involuntary muscles can continue to work in a paralyzed person. 

The heart also has its own "pacemaker" (the SA node) which doesn't depend on spinal nerves or the vagus nerve. This allows it to keep beating without any connection to the brain.

The diaphragm _does_ depend on the spinal nerves, so a person from the neck down typically needs a ventilator or other breathing support.