The term subcortical motor system refers to one of three functionally defined parts of the cerebrospinal trunk. It consists of eight multinuclear structures, which are involved primarily in the control of external behavior through the somatic musculature and the activity of internal organs through the autonomic nervous system ( Swanson-2003 ). The other subdivisions of the cerebrospinal trunk are the subcortical sensory systems and the behavioral state system ( Swanson-2004 ).