Why does cutting out part of Orochimaru’s soul cause him to lose the use of his arms? When Orochimaru and the Third Hokage fight after the Chunin exam, the Third Hokage has the Shinigami cut out part of his soul, "taking away his jutsu" by making him lose the use of his arms. How does that work? Why does it specifically make his arms not work? Logically, it would pull from the part was the farthest from the chest where it was being pulled from, which would be the feet. Why is that not what happens?
I've just re-watched the scene in the anime where that happened, and it looked to me like the death god was clearly pulling on the part of Orochimaru's spirit that controls his arms(you can see hands at the end).  That just happens to be where the death god was pulling on, and it happens to only have been pulled out to his elbows or so.  

Maybe the 3rd drew the arms out on purpose because he deemed that to be the easiest or most effective thing to pull out first in-case he only had to partially do the job.  

There's really not much more to it than that.