The Mixer is a neural Juke Box which holds records of all the motor behaviors we have learned throughout life.
The Mixer, then, is a storage mechanism for all of the motor patterns (praxis) we have learned throughout our lives. Apraxia, you remember is a problem in retrieving motor behaviors.
This includes, walking, eating, brushing our teeth, tying our shoe laces, dressing, playing a musical instrument, performing sports and, of course, speech. The Mixer is like the old fashioned juke box that brings up a record upon request.
If we wish to do something or say something, the message is sent to the mixer which finds the proper motor patterns and sends this information to the transducers to be executed.
NOTES: Here are some ideas for thearpy on Apraxia.
NOTES: Probably more citations than you ever wanted on Apraxia.