Cortical regions involved in voluntary movement

Voluntary movement occurs in a very different manner from reflex induced movements. Unlike reflexes, voluntary movements require planning and accurate execution. The process begins with the decision to move which occurs internally, and is followed by the activation of several cortical regions, each with a specific role in the production of deliberate movements. The premotor area is a region involved in the programming aspect of movements. It is where organization of the sequences in which motor cortical regions will be activated occurs. Part of the function of the premotor regions is to assist the motor cortex in orchestrating movements, much like the steering wheel controls the car, while alone it does not move the car, it is essential for directing when to turn. It is in the premotor cortex that sequencing of motor outputs using sensory information occurs. This is an important aspect of how the CNS coordinates distal movements while maintaining postural support and coordination.

Much like the premotor cortex, the supplementary motor area (SMA) also projects to the primary motor cortex. The SMA is important in the coordination of bimanual movements. While the SMA does not program the actual movements to be performed by either side, it does activate both movements in a coordinated manner, using higher inputs as well as sensory information. An example of why this is important can be illustrated with an example of someone pouring water into a glass being held by one hand, while holding the original glass container in the other. As the glass fills up, more force is required from that arm in order to maintain its stability. While the brain has to compensate for increased weight on the arm holding the glass, it also must account for the weight changes in the arm holding the original container, which slowly becomes lighter.

Lastly the primary motor cortex is where much of the input from the SMA, premotor cortex as well as sensory association areas converge. This is the region directly involved in controlling the activity of motoneurons. It does so by storing motor synergy information, in other words, neurons in the motor cortex have millions of combinations of “movement programs” that can be activated and relayed to the appropriate motoneurons. These movement programs can be thought as predetermined combinations of muscle inputs that produce a specific movement. As consequence of this, there are multiple representations of the same muscles within the primary motor cortex.


Cheney PD (1985), Role of cerebral cortex in voluntary movements. A review. Phys Ther 65:624-35

Kandel ER, Schwartz JH, Jessell TM (2000). Principles of Neural Science, 4th edition. New York: McGraw-Hill

MacKay WA (1999). Neurophysiology without tears, 3rd edition. Toronto: Sefalotek Ltd.