Character Rigging and Mesh Deformations rotating and shrinking strangely around joint This time, I began to rig a mesh through weight painting and deformations so I could achieve an accurate effect to my liking. For all my characters before, I have used object rigging, (Without Vertex groups as I never needed to have some).

However, this time I have an arm with two bones, One for the forearm and one for the wrist. When I rotate the wrist, it works correctly, but once I rotate the forearm, there are a specific pair of circular vertices that work strangely.

Here is the weight paint and arm at rest position:


The Yellow and light blue ones deform once I rotate the bone.


Like so. 
It is strange because I have an armature modifier applied to the object with preserved volume checked. Yet it seems as if those sets of vertices do not follow the command; they seem to be moving closer and closer to the joint whilst shrinking as I rotate the bone.

Here is what the weight values of the second bone are:


Any suggestions or wisdom would be appreciated, and I can always upload the .blend if you ask me to.
Thank you.

Here is the .blend file:
Select your Mesh and delete all vertex groups and all modifiers as shown:


Select your Mesh then select your armature using Shift+RightClick and hit Ctrl+P then choose With Empty Groups:

Switch to Pose Mode then select the two bones LWrist and LShoulder then select the mesh using Shift+RightClick as shown below:


Switch to weight painting mode and select Assign Automatic From Bones from the Weights menu as shown below:



Done, now the mesh will have weights assigned to these bones with good deformations as shown below: