Sorry to hear this Howard. Hope it heals soon.
There is an electronic sensor sorta of like the that in a GFI (ground fault interrupter). So flesh contact is detected in a very small fraction of a second. That then causes a part to launch itself into the blade teeth jamming the blade and thus an instant stop. This all happens so darn fast you wont even get a scratch. But you will have to buy a new blade as the original is destroyed to save you injury. I don't know if the violent blade stop causes any damage to the rest of the saw.
A new blade is a very worthwhile sacrifice versus what could happen.
I found out how fast a GFI is a couple of times. A old metal cased hand tool had a direct short from hot side to case. I never felt the slightest tingle, just heard the GFI pop and lost bench power. I am a little slow at times. I reset the GFI and reached for the tool a second time. Then went duh, I think something is wrong here.
Ken