voluntary motor control

Examples of voluntary motor control in the following topics:

• Motor Areas

  • The motor areas, arranged like a pair of headphones across both cortex hemispheres, are involved in the control of voluntary movements.
  • The motor areas are very closely related to the control of voluntary movements, especially fine movements performed by the hand.
  • The right half of the motor area controls the left side of the body, and the left half of the motor area controls the right side of the body.
  • Primary motor cortex: Main contributor to the generation of neural impulses that control the execution of movement.
  • Premotor cortex: Located anterior to the primary motor cortex and responsible for some aspects of motor control.

• Sensory and Motor Tracts

  • The spinothalamic tract is a somatosensory tract and the corticospinal tract is a motor tract.
  • It contains mostly motor axons.
  • The corticospinal tract is concerned specifically with discrete, voluntary, skilled movements, such as the precise movement of fingers and toes.
  • The primary purpose of the corticospinal tract is to maintain voluntary motor control of the body and limbs.
  • However, control of trunk muscles is on the same side of the body.

• Neural Mechanisms (Cortex)

  • Voluntary respiration is any type of respiration that is under conscious control.
  • The primary motor cortex is the neural center for voluntary respiratory control.
  • More broadly, the motor cortex is responsible for initiating any voluntary muscular movement.
  • The inferior portion of the primary motor cortex may be involved in controlled exhalation.
  • Each part of the primary motor cortex controls a different part of the body.

• Basal Ganglia

  • One of the most intensively studied functions of the basal ganglia (BG) is its role in controlling precise eye movements.
  • The basal ganglia are associated with a variety of functions, including voluntary motor control, procedural learning relating to routine behaviors or "habits" such as bruxism, eye movements, and cognitive, emotional functions.
  • Experimental studies show that the basal ganglia exert an inhibitory influence on a number of motor systems, and that a release of this inhibition permits a motor system to become active.
  • The pallidum receives its most important input from the striatum (either directly or indirectly), and sends inhibitory output to a number of motor-related areas, including the part of the thalamus that projects to the motor-related areas of the cortex.
  • Basal ganglia dysfunction is also implicated in some other disorders of behavior control such as the Tourette's syndrome, ballismus (particularly hemibalismus), obsessive–compulsive disorder (OCD), and Wilson's disease (Hepatolenticular degeneration).

• Spinal Cord Trauma

  • SCI can have a number of causes; examples include motor vehicle accidents, falls, sports injuries, and violence.
  • Research into treatments for spinal cord injuries includes controlled hypothermia and stem cells, although many treatments have not been studied thoroughly and very little new research has been implemented in standard care.
  • This is typically a transient phase and if the person recovers any motor function below the neurological level, that person essentially becomes a motor incomplete, i.e.
  • E indicates "normal" where motor and sensory scores are normal.
  • A group of muscles innervated through a specific part of the spine is called a myotome, and injury to the spine can cause problems with voluntary motor control.

• Organization of Motor Neuron Pathways

  • The motor pathway, also called the pyramidal tract or the corticospinal tract, serves as the motor pathway for upper motor neuronal signals coming from the cerebral cortex and from primitive brainstem motor nuclei.
  • Peripheral motor nerves carry the motor impulses from the anterior horn to the voluntary muscles.
  • The midbrain nuclei include four motor tracts that send upper motor neuronal axons down the spinal cord to lower motor neurons.
  • The lateral tract contains upper motor neuronal axons that synapse on the dorsal lateral lower motor neurons, which are involved in distal limb control.
  • The ventromedial lower motor neurons control the large, postural muscles of the axial skeleton.

• Comparing the Somatic and Autonomic Nervous Systems

  • The peripheral nervous system includes both a voluntary, somatic branch and an involuntary division regulating visceral functions.
  • The somatic nervous system (SoNS) is the part of the peripheral nervous system associated with the voluntary control of body movements via skeletal muscles.
  • The somatic nervous system controls all voluntary muscular systems within the body, and also mediates involuntary reflex arcs.
  • Spinal nerves are peripheral nerves that carry sensory information into the spinal cord and motor commands.
  • Association nerves integrate sensory input and motor output, numbering in the thousands.

• Motor Units

  • The motor unit is the functional unit of muscle contraction and includes the motor nerve fiber and the muscle fibers it innervates.
  • A motor unit consists of the motor neuron and the grouping of muscle fibers innervated by the neuron.
  • Thus, small motor units can exercise greater precision of movement compared to larger motor units.
  • Groups of motor units are innervated to coordinate contraction of a whole muscle and generate appropriate movement; all of the motor units within a muscle are considered a motor pool.
  • These multiple motor units of different sizes within a motor pool allow for very fine control of force either spatially or temporally.

• Disorders of the Basal Ganglia

  • If something causes too much basal ganglia output, then the thalamocortical projection neurons become too inhibited and one cannot initiate voluntary movement.
  • Along with other structures, the basal ganglia are part of a circuit that is integral to voluntary motor function.
  • These areas are thought to control not only motor function but also oculomotor, prefrontal, associative, and limbic areas.
  • Hypokinetic disorders are movement disorders that are described as having reduced motor function.
  • Distinguish between hypokinetic, hyperkinetic, and non-motor disorders of the basal ganglia

• Overview of the Cerebrum

  • With the assistance of the cerebellum, the cerebrum controls all voluntary actions in the body.
  • With the assistance of the cerebellum, the cerebrum controls all voluntary actions in the body.
  • The right hemisphere controls and processes signals from the left side of the body, while the left hemisphere controls and processes signals from the right side of the body.
  • Upper motor neurons in the primary motor cortex send their axons to the brainstem and spinal cord to synapse on the lower motor neurons, which innervate the muscles.
  • Damage to motor areas of cortex can lead to certain types of motor neuron disease.