MOTOR ANALYZER

From Big Medical Encyclopedia

MOTOR ANALYZER (synonym: kinaesthetic analyzer, proprioceptive analyzer, muscular analyzer) — the physiological system transferring and processing information from receptors of the skeletal and muscular device (muscular, tendinous, joint and bone) and participating in the organization and implementation of coordinate movements. And., as well as any other analyzer, consists of three main departments: perceiving, conduction and cortical, the ascending and descending interactions which are closely connected among themselves by a complex system (see. Analyzers , Brain ).

Scheme of a motor analyzer: α and γ — motor-neurons of a spinal cord (SPM), regulating activity of muscles, obtain information from muscle spindles (1), tendinous (2) and joint receptors (3) on shoots of an afferent neuron of a spinal ganglion (4). To the same motor-neurons on the pyramidal path (PP) the regulating influences from bark of hemicerebrums (K) and the myelencephalon (M) come. Regulation of movements is provided with consensual activity of all systems (it is specified by shooters), including striopallidal (Union of Right Forces), a thalamus (T), the mesencephalon (M), a cerebellum (M) and a spinal cord.

Necessary condition of normal muscle performance is obtaining information on extent of reduction of each of muscles. One of the central places in the alarm system and a condition of muscles occupies activity of so-called intrafusal muscle fibers — the high-differentiated receptor formations of motive system. Several such fibers concluded in the special capsule form a muscle spindle (fig). The usual muscle fibers which are lying out of this capsule and not performing functions of receptors carry to extrafusal muscle fibers. Intrafusal fibers pass along a muscle parallel to the ground mass of usual muscle fibers and, as a rule, are attached by one end to extrafusal fiber, and another — to a sinew. At relaxation of a muscle muscle spindles stretch, in intrafusal fibers the impulsation arriving on afferent nerve fibril to motor-neurons of a spinal cord and overlying structures of D. is generated and. Peripheral sites of intrafusal fibers are innervated by the gamma and efferent nerve fibrils of gamma motor-neurons of a spinal cord regulating degree of stretching of intrafusal fibers. On gamma and efferent fibers impulses arrive continuously therefore intrafusal fibers always are in a condition of nek-ry reduction that in turn involves a continuity of the impulsation from intrafusal fibers addressed to alpha motor-neurons of a spinal cord. alpha and Efferent nerve fibrils of these motor-neurons innervate extrafusal muscle fibers. Similar ratios in an innervation intra-and extrafusal muscle fibers are the cornerstone of reflex regulation of a tone of skeletal muscles.

Activity both gamma, and alpha motor-neurons is under continuous control of a brain which is provided with the descending influences of structures of bark of big hemispheres, a red kernel, a cerebellum, a reticular formation and kernels of a myelencephalon. Each underlying level D. and. it is regulated by the overlying centers.

The main afferent way, on Krom comes information from receptors of joints and muscles to hemispheres of a bigger brain, passes in structure of back cords of a spinal cord through kernels of a myelencephalon, fiber of a medial loop, a kernel of a thalamus and comes to an end in somatosensory area of a cerebral cortex. High speed of carrying out information on signs of irritation, the accurate space organization of sensitivity from the opposite side of a body is characteristic of this path.

Pyramidal system (see), D. originating in cortical department and. (pyramidal cells of sensomotor bark), exercises control over underlying brain structures up to a spinal cord. Generally regulating pyramidal influences are expressed in braking of activity of the muscles participating in anti-gravitational tonic reflexes and simplification of phase flexion movements. The pyramidal system can influence receipt to motor-neurons of a spinal cord of a background afferent impulsation, edges plays an important role in maintenance of their tonic activity.

Many cells of cortical department of D. and. are influenced practically by all analyzers that allows D. and. to perform the major integrative functions. Pyramidal and Extrapyramidal systems carry out excitement not only to elements of a spinal cord, but also to many kernels of a brain, carrying out thus function of cortical control practically of all departments of c. N of page.

Prefrontal (frontal) shares of parencephalons progressively develop and reach the greatest perfection at primacies and the person, being at them the main device of formation of complete programs of motive behavior («strategy» of the movement). Actually somatosensory bark as a collector of various type of information carries out the main role in touch control of the current movement («tactics» of the movement).

Research of physiology of D. and. gains great value in connection with problems of a space and air medicine, neurocybernetics, physiology of work and other sciences.

Considerable influence on development of ideas of D.'s activity and. rendered N. A. Bernstein's works (about creation of movements in connection with activity of various structures and levels of c. N of page), J. Ekkll, P. G. Kostiuk, R. Granit, etc. in which questions of relationship of neural activity of various departments of c are in details developed. N of page and central regulation of muscle receptors.

See also Motoriums, ways , Movements .


Bibliography: Batuyev A. S. Functions of a motor analyzer, L., 1970; Gambaryan L. S. Questions of physiology of a motor analyzer, M., 1962; Granite P * Bases of regulation of movements, the lane with English, M., 1973; Kostiuk P. G. Structure and functions of the descending systems of a spinal cord, L., 1973; To at to at-e in L. A. Struktur of a motor analyzer, L., 1968.

A.S. Batuyev.

Яндекс.Метрика