Simple rigging problem?

I want to rig this simple mesh: a trunk with two arms but
1/ when I pull the head of the trunk the “shoulders” must move accordingly.
2/ When I pull a arm to the bottom, the arm must be stretched and the trunk must bend a bit to that direction.

I tried with bbones but i gave some strange results (I joined the part of the mesh) before trying.

Help will be appreciated.


spine_cord_00.blend (481 KB)

You need to use custom handle reference. Try this Blender 2.78 Bendy Bones Tutorial