We have all seen posts of men not understanding women's anatomy. How have you experienced this the other way?
For instance, My wife confidently told me that men who jerk off a lot actually stretch the skin of their penises permanently. If that were the case, mine would be looped around my waist.
Yes, I am aware of Jelqing, it doesn't work. That is not what she was referencing.
My wife was in a panic when we had a baby boy and she realised that male kids, even babies get boners. She thought that didn't happen till puberty. I told her, that's why a kid who can't lift a book can get one at any moment once they hit puberty, cause that thing works itself out without our knowledge or consent and while we sleep. I wish the rest of my muscles worked out while I slept.
The corpos cavernosum does indeed fill with blood to cause an erection. There are however several muscles in and attached to the penis.
You have to remember the penis actually extends into the body of the person slightly, and is held by two main muscle groups. The bulbospongious muscle (ever squeeze a water balloon so it stretches tighter? It's like that for penis blood), and the ischiocavernosus (a check valve for blood basically).
There is also the suspensory ligament, which is how you can make it nod hello.