Body processes

Voluntary Motor Skills – Function, Task & Diseases

Voluntary motor skills

A motor action is a result of an interaction between cognitive, motor, and sensory processes. Voluntary actions, on the other hand, arise schematically from a completed motor process. Occurs in a human z. B. a paralysis or if his movements are uncontrolled, the voluntary motor function is disturbed. This is not due to damaged muscles but to nerve damage .

What is voluntary motor function?

Voluntary motor control is the movement of the body that is controlled by will or consciousness . This process takes place in the primary motor cortex, more precisely in the pyramidal system, which is located in the cerebral cortex and has the shape of a pyramid due to the fiber connections running there. All the converging processes of the nerve cells and the central motor neurons form the skeletal muscles .

In these association regions of the cerebrum, the plan for voluntary motor activity develops. Here the movements necessary for the execution are prepared. In order to be able to imagine the movement and execution, the supplementary motor area is required. The movement plan is controlled by the cerebellum and the basal ganglia . The information goes through the thalamus and into the motor cortex, where it then travels as impulses through the pyramidal and extrapyramidal pathways to the second motor neuron and initiates muscle movement.

The upper motor neuron is responsible for voluntary motor activity, which also controls posture . All volitional actions are coordinated sequences of movements that run very precisely. For example, if a person moves their fingers, this happens as a voluntary motor function via the pyramidal tract in order to then carry out a specific action that corresponds to the will.

function & task

Voluntary motor skills are based on volitional movements that depend on a situation and can also take a different course. Volitional actions in turn are based on motives, action intentions, objectives, the decision or volitional impulse, the movement planning, the execution of the action, the perception of it and the evaluation of what has been achieved. 

The entire process is arbitrary, as it is determined by consideration and decision-making options. On the other hand, there are the involuntary movements, which are mostly pure reflexes or simply unconsciously performed habitual actions. Reflexes are much more stereotyped responses to stimuli. They pass unconscious. An example is the pupillary reflex .

In contrast, the stored action in voluntary movements improves with experience, while the reflex is not subject to change. Voluntary motor activity does not arise from necessity, while reflexes are always stimulus responses and are generated by the central nervous system . The pyramidal system, in turn, can control the information content of stimuli without triggering a movement.

In the case of volitional actions, a distinction is made between intentions that lead to an action and those that take place during such an action. These actions are severely impaired by neuronal damage or fail altogether. This in turn happens z. B. during a sleep attack.

The seat of the will is the prefrontal cortex. It plays a crucial role in all decisions and movements. The impulses take place via the region of the parietal lobe, which controls all sensory information, as well as attention , memory and orientation in space. All motor memories are stored there. The voluntary motor function is dependent on complex neuronal control conditions in different brain regions.

Diseases & Ailments

Many of the stimulations via the motor cortex activate different muscles at the same time. Outer areas activate proximal muscles, central both these and distal muscles. This creates complex movements that no longer interact with each other if there is a disturbance. 

is e.g. If, for example, the pyramidal system is damaged, paralysis and loss of voluntary motor functions can occur. Defects in the first or second neuron are distinguished. If there is a disturbance in the pyramidal system, the extrapyramidal takes over control of some functions, so the paralysis does not have to be complete.

Most often, under such conditions, voluntary and fine motor skills are disturbed. Not only are the pathways in the pyramidal system inhibited, but others are also affected. Neurological symptoms are then degenerating reflexes, including, for example, the Babinski reflex . Epilepsy can also trigger muscle twitches that follow the somatotopy of the motor cortex.

In medicine, these neurological symptoms are called pyramidal signs . This creates very specific reflexes in the extremities, which have different names.

Disorders in the extrapyramidal system, in turn, trigger even more serious diseases. An “extrapyramidal” movement always means conditions in which the movement sequences are either not controlled by the pyramidal path or run outside of it. Voluntary motor activity takes place via both pyramidal and extrapyramidal pathways. Lesions result in movement disorders that are neurological or genetic. The consequences are diseases such as Parkinson’s or Huntington ‘s disease .

Diseases of this type disrupt muscle tone because lesions occur in the primitive subcortical nuclei. This leads to abnormal or involuntary movements. Parkinson’s disease is a voluntary motor disorder and develops into a slowly progressing, degenerative disease. Its symptoms usually appear in old age. It causes hypokinetic movement disorders based on the overactivity of the output nuclei. Inhibitions are then caused in the thalamus, and the transmission to the various projection pathways then no longer takes place. Under these conditions, facial expressions are lost and arms and legs twitch uncontrollably.

Disturbances of consciousness or speech are also manifestations of a disturbed voluntary motor function, which are associated with defective activity of the ascending reticular activation system.

Website | + posts

Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.