If you visualize the spine as a freeway with a series of ramps, that’s roughly how it’s set up. There’s two generic scenarios - the first is for an accident on the freeway blocking all traffic. The second is for an accident at a ramp stopping traffic from taking that ramp, but traffic on the freeway continues.
With the spine, the first scenario would be what Padeye’s father has - his spinal cord has been severed at the T10 level - roughly around the level of one’s navel. Nothing’s getting through, so the legs aren’t working. Probably as a self-preservation means, most of the abdominal functons such as bowel and bladder control come from higher-up connections.
I’m a walking example of the second scenario. A neck injury seven years ago left me unable to use my left arm for a while - I had a string of herniations from C4-5 to C7-T1. The spinal cord itself was fine, but the off-ramps were blocked. With time and patience, the herniations reduced to the point that the off-ramps were passable, but cars were getting scratched and dented trying to squeeze past the wreckage. In other words, the arm is usable for the most part, but there’s numbness, tingling, and occasional loss of function.