The regulation I tion phase (dynamic) and postural (static) muscle activity etc. and neem together various structures of the brain – spinal cord, brain stem, cerebellum, thalamus, basal ganglia and the cerebral cortex. Ka w dy of the brain to perform certain tasks or functions, Concrete t character which depends on the type of muscle activity. Thus, when the arbitrary actions necessary to form a focused impulse to action (drive, motivation), create a deputy s villages, or target of action, define the implementation plan design, ie. e. a program of action and begin to implement the plan up, use s Zuya thus adequate for this action pose. Distribution of I of affection between the parts of the brain in this case probably will be: motive and a specific goal, or vision, action is formed in the motivation and onnyh and associative areas of the neocortex as well as in the structures limbich e tion system. A program, or plan, action is selected from an array of existing programs or is formed anew. In either case, the associative and motor zones of the new cortex take part in the formation of an action program with the obligatory participation of the basal nuclei of the cerebellum and the thalamus. The specific implementation of the program is carried out , I is implanted by skeletal muscles under the influence of impulses from the alpha-motoneurons of the spinal cord, which receive the necessary commands for the pyramidal path from the motor cortex of the large hemispheres, as well as for the descending paths from the components of the extrapyramidal system , t. e. from the basal nuclei, cerebellum and brain stem.
Each brain neuronal mechanism is involved in the regulation phase and within the muscle activity on the proposal number called physiologists s INDICATES propulsion system or a motor center. Distinguish between the two and the intestinal systems of the spinal cord, stem, cerebellum, basal nuclei, and the lamus and the new cortex. In the arrangement of the structures responsible for the retention of posture and the regulation of movements (r. e. motor or motor, center), there is a clear hierarchy, reflecting the gradual usovershens t -existence of motor function in the process of evolution, which were accompanied railway was given not only to the restructuring of existing motor systems, but also nadstraivaniem new (controlling) bodies responsible for ODA e divided traffic program .
In the spinal cord is the main element of the whole motor system of the brain – alpha motoneurons . The axons of these neurons are the only channel connecting the nervous system with the skeletal muscles. Only excitation of the alpha-motoneuron leads to activation of the corresponding muscle fibers. In the spinal cord, there are two mechanisms that activate alpha-motoneurons. The first mechanism – is a direct downward impact on the alpha-motoneurons, such in of action can have giant axons of pyramidal cells of Betz located in the motor cortex. However, activation of alpha-moto-neurons is often carried out indirectly through intercalary not minutes Rhone (whose number is enormous in the spinal cord) and gamma motor neurons . The latter activates intrafusal muscle fibers, thereby increasing the sensitivity of muscle receptors, t. e. muscle spindles to stretch the muscles. The consequence of this is to increase the flow and the m pulses coming from muscle spindles to the alpha-motoneurons (including chi with les through intercalary neurons), which leads to the stimulation of alpha motoneurons and innervated muscle fibers. Such a mechanism for activating alpha motoneurons is called a gamma loop. So, gamma-motoneurons, in fact, act as intercalary neurons, but with a special variant of excitation, t. e. with the participation of peripheral mediator in the form of muscle spindles. In addition, in the spinal cord there are neurons that play the role of a pacemaker, t. e. Automatic generator momentum v cos, excitatory alpha motoneurons. By this mechanism autom a tically no signals from supraspinal motor systems may be stepping movements. These neurons form the so called e my central pacing generator, which in a healthy person, beliefs about yatnee all completely converted supraspinal control of the jet to the tour (from the first months of postnatal development).
The second “floor” control motor activity are motor brainstem system (including vestibular nucleus, red nucleus, reticular formation of the medulla oblongata and bridge quadrigemina nucleus) involving regulated muscle tone, organd nizuetsya corresponding position, including allowing performs D e purposefully movement. The motor systems of the brain stem are controlled by the cerebellum, basal nuclei, thalamus and motor cortex of the cerebral hemispheres. In general, stem motor systems are components of the extrapyramidal system. In this same system are mo of zhechok, basal ganglia and the thalamus, which can be roughly classified as tert s him “floor” traffic control. Cerebellum and basal nuclei There are two main motor tasks. First, they control the functions of the brainstem motor systems, including the vestibular nuclei, the red nucleus and the reticular formation. Secondly, they provide and move the motor cortex of the big hemispheres with the necessary action programs and correct the motor commands going from the motor cortex to the neurons of the spinal cord along the pyramidal path. The fourth ‘floor and pulp, “traffic management is the cerebral cortex, in the chi to le her associative and motor area. The associative areas (frontal and parietal cortex) are formed motivation actions and his “deputy ‘s villages, ”or goal, as well as a program, or plan, a focused action. To evaluate the “design” and selecting the particular program steps Item p mation of the association cortex supplied simultaneously to the basal nuclei, and cerebellum, from which it returns through the nucleus of the thalamus to the cortex (primarily to its motor area). From the giant pyramidal cells of the motor cortex Betz information n and controlled directly to the spinal cord neurons (as pyramidal or corticospinal, path). Simultaneously, in order to correct Navigating e Nia and to arbitrary purposeful movement osusches t was specifically in optimal comfortable position, a signal from the pyramidal cells of Betz sent by extrapyramidal pathways to components ekstrapirami d hydrochloric system, including the basal nuclei, cerebellum, vestibular nuclei, red nucleus, reticular formation of the medulla oblongata and the bridge. All cord motor systems operate using Obra T -coupling, ie. e. on the basis of sensory information, including those coming from muscle spindles, tendon and joint receptors, from tactile receptors and receptors of the vestibular apparatus.
At the spinal level in humans, only the simplest coordinates and nations, for example, reciprocal inhibition of antagonist muscles, proceed . Brainstem provides coordination body proper installation space consisting of n stve. An important role in the coordination of movement belongs to the cerebellum, a cat about ing provides such quality traffic as fluency, accuracy, neo b walk force. Hemisphere brain (cortex and basal nucleus) provide the most delicate coordination – motor reactions Prio b Retenu in individual life. However, the implementation of these reactions, of course, is based on the work of the motor systems of the spinal cord and brainstem.