TV show life in the ER

[nec209]

I thought damge to nerves cannot fix them self? How do they hook up some one cut off arm or finger than? Or hook up some one cut off leg?

 

How can doctors fix nerves like in the show life in the ER? I know they cannot hook any thing to the central nervous system or fix any nerves in the central nervous system .

 

Than I hear reports over time the person may walk .Is this do to the spine bypass the bad part or re-grow pass the bad part?

 

Why is this sush yes and no in the science world or a may be.