This fancy spine-some worm uses a series of 3D matrix transformations and rotations. You may find bit hard to understand matrices, especially if you had very little math in school.. like myself.
In general this gives processing great power to handle wide range of transformations and what is the best to store and apply more at once.
For some basic insight I suggest reading:
I will try to bring some parsed and rigged mesh soon.. just when I have some time to dig in fully.