I know that I risk inviting some bathroom humor here
, but I'd like to reinforce Wristtwister's point about the vagus nerve from a nursing perspective. A major nerve of the parasympathetic system, the vagus is certainly nothing to fool with, and heart surgeons aren't the only medical professionals who are wary of messing with it.
As Wristtwister has pointed out, the vagus innervates almost every major organ in the body, including the colon. Nurses, who regularly have to help patients with affairs "down there," are taught to be wary while administering suppositories or performing "dig-stims" since such interventions can produce cardiac irregularities via stimulation of vagal nerve endings in the rectum—especially in patients with heart conditions. Far more than an odd bit of medical esoterica, this is a matter of serious concern and routine caution on the hospital floor.
Now, I'm not suggesting that people are going to be inordinately curious about checking out THIS particular pressure point in the dojo.
I'm just calling attention to the fact that, for all our amazing powers of recovery, our bodies are weirdly delicate in ways that are likely to surprise us.
When learning about things like nerve strikes and blood vessel sealing, therefore, we really do need to be careful, and we owe it to ourselves and to our training partners to hit the books and get something of a medical education in the process.