Rigging the mouth

Added bones around the mouth on one side and named them accordingly. selected one and used the shift + S tool to make the selection the cursor and added a linking bone selected the first bone and the top of the newly added connection bone and used the shift + s tool to make the cursor the cursor the selection. Extruded the bones as well this is the result:



mirrored over the bones by duplicating and flipping the names.
switched direction with W and switch direction with the connection bones.


linked the two middle connector bones on the top and bottom with Ctrl + P and kept them connected.

Added 4 segments to each connector bone:



Bone connectors are selected and Ctrl + N is used to clear the roll of the segments.

the corner of the mouth bones parented to the connector bones and kept offset.

In pose mode the connector bone and the mouth bone are shift selected and a strech to constrain was added with Ctrl, Alt and C. This allow the connector bone to stretch to where the mouth bones are moved. Repeated this around the mouth.

Selected the mouth rig and duplicated it for the eye lids.