Your skin actually has quite a lot of resistance especially compared to a copper wire, while it's definitely bad news for a current to be flowing through your nerves it would need to get there first. Current doesn't really 'choose' a particular path either; if you have a potential difference V between two points the current will take all paths available between them and Ohm's law I = V/R tells us that the current will be greatest through the path with the least resistance. The reason you don't get a shock when you touch a properly insulated wire is that the path that includes your finger also includes the resistance R of the insulation which is very high so correspondingly I is very low.