Regardless of exactly how it happened, the result is, I have a boy with a still swollen hand more than 24 hours post-injury and an even more swollen thumb with limited range of motion. It doesn't hurt unless it is moved or touched, and he does have functionality of most of his hand and even the first joint in his thumb. But the swelling persists and the tenderness persists and the inability to make a fist persists, so we are headed to the pediatrician tomorrow to determine if any sort of damage was sustained. I think he got very lucky, because the way my dad describes it, it sounds like there was an excellent chance of a dislocated shoulder or cracked wrist, so a swollen hand seems to be a fair price, really. But we will see what the doctor has to say and find out if we need to do anything further for the munchkin and his slightly gimpy hand. Now would be a lovely time to have insurance, wouldn't it?
PS: Sunday Song post below, if you're interested. :)
ETA: We saw the pediatrician. Although it is still tender and swollen, she doesn't think anything is broken, but she gave us a script for x-rays in case the swelling isn't gone in a couple days.