From Big Medical Encyclopedia

POSE — the fixed position of a body of the person and his separate parts in space in the conditions of gravitational field of Earth. The item serves as a starting point for the movement and limits the movements (not any movement can be carried out in a certain P.). At the same time any movement inevitably leads to change of a pose. The item can also express an emotional state (the menacing P., quiet P., etc.).

Mechanisms of maintenance of a vertical pose are most studied.

Vertical P. was created as a result of long evolution of the person. Vertical P. and the speech made the person capable to work and communication (see. Person ).

For maintenance of people by vertical P. uses not only a passive part of a musculoskeletal system, but also its active part, i.e. muscles of various parts of a body. In this regard the mechanism of management of a great number of the muscular groups participating in P.'s maintenance is very difficult.

In vertical P.'s studying conditionally allocate a number of aspects: 1) biophysical, within to-rogo the main attention of researchers attracts structure of muscular groups and bone educations, their relationship in the course of vertical P.'s formation (the main contribution to these researches was made by anatomists); 2) neurophysiological, the central question to-rogo is identification fiziol, mechanisms and nervous structures providing interaction of muscular groups and the bone and joint device both in the conditions of a static pose, and at a number of changes of position of a body in space; 3) the system aspect is characterized by drawing attention of researchers to integration of all mechanisms and structures of an organism for vertical P.'s implementation in uniform functional system; it is especially actively developed in the 70th.

Evolution of ideas of mechanisms of regulation of P. is closely connected with development of its methodical receptions (studying. Significant progress in understanding of mechanisms of maintenance of P. is connected with use of methods of a kefalografiya (definition of position of the head in space), bazometriya and especially stabilografiya (see) in combination with electromyography (see), electroencephalography (see), methods of evoked potentials, using microelectrode and stereotaxic technics (see. Stereotaxic method ), etc.

In the course of development of biophysical bases of implementation of vertical P. features of an arrangement of parts of a skeleton, the joints and muscles necessary for P. V maintenance studying of a statics the main contribution are studied anatomists — J. Borelli (1679), brothers E. F. W. Weber [E. E. F. W. Weber and E. F. W. Weber, 1836], Shtaffel made (F, Staffel, 1889). Their researches were directed to identification of localization of the center of gravity in the conditions of various options vertical to the Item. On the basis of these researches idea of «a normal rack», «normal situation» [Brown, Fischer was created (Gh. W. Braune, O. Fischer), 1889]. It was established that at «normal situation» the projection of the general center of gravity is located on 3 cm of a kpereda from ankle joints and is a point, through to-ruyu there passes the axis of symmetry for both half of a human body. In works of various researchers the projection of the center of gravity varies though in general it is in the area of a support of legs and is located kpered from a projection of ankle joints.

Neurophysiological development of a problem of the organization P. is directed to studying of spinal segmented mechanisms of maintenance muscular tone (see), features of supraspinal influences from various departments of c. N of page, on detection of value of various afferent systems in the course of maintenance of the Item.

Studying of nervous control of P. is based on idea that so-called slow phase muscle fibers (act as the main effector devices participating in P.'s implementation see. Muscles ), which provide a tonic component of P. Bystrye phase muscle fibers participate in correction of a physical activity and provide implementation of local phase motive acts (see. Movements ). According to character of effector devices there are features and in the nervous mechanisms regulating them. So, motor-neurons, the innervating slow fibers, by the size it is less, than motor-neurons, the innervating bystry fibers. According to it they have thinner axons and smaller lability. Segmented regulation of a muscle tone is connected with small alpha motor-neurons. They are that final nervous device which creates the activity on the basis of integration of all set of the vozbuzhdeniye coming to it both from segmented receptors and from other spinal and supraspinal nervous educations: cerebral cortex (see), reticular formation (see), cerebellum (see), myelencephalon (see), etc. The proprioceptive receptor device is presented by three types of receptors: 1) muscle spindles, 2) tendinous bodies of Golgi, 3) receptors of pressure (see. Proprioceptors ).

Afferent fibers from muscle spindles exert the facilitating impact on motor-neurons of the muscle and brake — on motor-neurons of antagonistic muscles. Afferent fibers from sinews exert brake impact on motor-neurons of the muscle and facilitating — on motor-neurons of antagonistic muscles [J. Ekkls, A. Lundberg, 1959]. Afferent fibers from receptors of pressure combine together with skin and high-threshold joint afferent fibers in group of offerers of a bending reflex. These receptors exert the facilitating impact on motor-neurons of sgibatel irrespective of in what muscle they are located. On motor-neurons of razgibatel they make brake action. These receptor influences generally also provide the mechanism of spinal adjustment of level of a muscle tone in the course of maintenance of the Item.

Muscle spindles represent group of receptors, sensitivity to-rykh is regulated by special neurons of a spinal cord — gamma motor-neurons (see. Spinal cord ), activity to-rykh is adjusted by Renshaw's cells causing brake effect in motor-neurons. Besides, activity of motor-neurons is regulated by supraspinal devices by means of mechanisms of presynaptic braking (see).

Vertical P.'s studying as uniform system includes also identification of the integrative principles which combine biophysical and neyrofiziol, mechanisms of formation of vertical P. Tak, Dubois-Raymond (R. Du Bois-Ray-mond, 1903) was one of the first, opposed the concept about a backbone as about passively balanced spring. He proved what without vigorous muscle performance to support; a backbone in the straightened situation it is impossible. Early basic researches of a complex neyrofiziol. the mechanisms which are the cornerstone of maintenance of a pose were executed in 1924 by Magnus.

In its researches it was shown that vertical P.'s organization is connected first of all with control of a set of local mechanisms and with their integration for obtaining cumulative effect, it, e.g., as adjusting reaction (see), arising from labirdtstny and cervical receptors (see. Magnus — Klein reflexes , Statokinetic reactions ).

The essential role in P.'s maintenance belongs to a vestibular mechanism (see. Vestibular analyzer ), to the visual analyzer (see) and to proprioceptors (see). However the mechanism of their interaction cannot provide high sensitivity of system of regulation of the Item. Significant progress in understanding of the mechanism of management of maintenance of vertical P. was promoted by the theory functional systems (see), developed by P. K. Anokhin. According to this theory vertical P.'s maintenance is result of interaction of many processes combined in uniform functional system where the dominant position and the regulating role belongs to c. N of page. The theory of functional systems considers vertical P.'s maintenance as a component of purposeful behavior of the person.

V. A. Polyantsev and G. Ts. Agayan (1980) established that vertical P.'s maintenance is carried out by an organism by means of not one, and always sets of programs of action. At the same time it was revealed that the nature of search of programs and their structure are indicators not only efficiency of process of maintenance of vertical P., but also serves as the indicator of a functional condition of the person, degree of his exhaustion and level of emotional pressure.

Pathological poses

Pathological poses are observed at many diseases, and various pathogeny is the cornerstone of them. At diseases and injuries of the musculoskeletal device patol. Items arise owing to mechanical restriction of movements in joints.

the Pose of the patient at a catatonic stupor with the phenomena of wax flexibility.

So, at Bekhterev's disease (see. Bekhtereva disease ) characteristic P. is defined by restriction of mobility of a backbone and its fixing in the provision of an inclination of the case forward. At the heart of a pathogeny of disturbances of P. at various nervous and mental diseases disturbance of nervous control of P. and a muscle tone lies. Characteristic P. is observed at parkinsonism (see): the back is bent, the head is inclined to a breast, forearms are bent in elbow, brushes — in radiocarpal joints. Pathogeny of this patol. The item is closely connected with increase of extrapyramidal muscular rigidity. Also Vernike's pose — Mann is peculiar at the central spastic hemiplegia (see. Hemiplegia ), in a pathogeny the cut plays an important role increase in a tone of certain muscles of extremities on spastic type. Vertical P.'s disturbance, especially in the conditions of lack of correction by sight, is noted at defeat of a vestibular analyzer, a cerebellum, frontal lobe of a brain, and also at switching off of afferent impulses of a deep myesthesia (e.g., at back to tabes). Patol. Items are observed also at other diseases and syndromes of defeat of the central and peripheral nervous system (see. Ataxy , Athetosis double , Hyperkinesias , Gormetoniya , Children's paralyzes , Trembling paralysis , the Torsion dystonia etc.). At defeat median nerve (see) a hand has an appearance of a monkey brush, at defeat elbow nerve (see) — a sharp-clawed paw, at defeat beam nerve (see) the hanging-down brush is observed, at damage of a fibular nerve (see. Sciatic nerve ) — the hanging-down foot. Patol. Items are quite often noted at mental diseases. So, e.g., the catatonic stupor with wax flexibility (fig.) is characterized patol, fixing by the given P.: the head turned by the doctor, a hand, a leg remain long time in the same situation, cut it is given (see. Catatonic syndrome ). The stupor with catalepsy differs in a full immovability. Elaborate hysterical P. are various (see. Hysteria ).

At a research of the motive sphere and a tone usually study P. Inogd only one external observation allows to make the diagnosis as, e.g., in cases of the expressed parkinsonism. However the thicket needs an objective research. By a research of passive movements in joints find out existence or lack of the mechanical reasons patol. Item. By means of active movements find out a possibility of any change of P. Ustoychivost of vertical P. investigate in position of the patient standing with the legs made together — Romberg's pose (see. Romberg symptom ). Painful phenomena define so-called antalgichesky P., at a cut the smallest morbidity as, e.g., at neuritis of a sciatic nerve when bending of a shin reduces a tension of a nerve and reduces pain is reached. At a research P. define a muscle tone, the Item can be connected with increase or decrease to-rogo pathological. Gives valuable information on muscular activity miografiya (see), and also a-foot phenomenon, a phenomenon of a shin (see. Postural reflexes ), static reactions of balance (see. Balance of a body ), reflex of straightening of Rademaker [Rademaker (G. G. J. Rademaker)]. At this reflex if standing investigated easily to push forward, P. remains thanks to a reflex muscle tension of legs («reaction of a column»). At sudden capsizing of the studied patient on a back from a sitting position with the legs of a leg bent in knees become straight. Disturbance of reflexes of straightening provides on defeat of a brainstem below of red kernels.

Treatment of disturbances of P. generally comes down to conservative or operational treatment of a basic disease. In cases when P. is connected with increase in a muscle tone, apply the pharmaceuticals reducing a muscle tone, and at antalgichesky P. — analgesic means. Sometimes at P. depending from patol, changes of a musculoskeletal system, use retentive bandages and the special fixing devices. G1. long motionless standing can be followed by disturbance of blood circulation and difficulty of cordial activity. In this regard those specialists are recommended to do periodic warm-ups during the working day, work to-rykh is connected with P. of long motionless standing.

For prevention patol. At children's age fight against vicious P.' fixing by the letter, playing a grand piano is necessary for the item, etc.

See also Myostatics .

Bibliography: Anokhin P. K. Biology and neurophysiology of a conditioned reflex, M., 1968; Batuyev A. S. both Tairov O. P. Mozg and organization of movements, JI., 1978; Bogolepov N. K. Disturbances of motive functions at vascular damages of a brain, page 400, M., 1953, bibliogr.; Granite P. Bases of regulation of movements, the lane with English, page 367, M., 1973, bibliogr.; Kerbi-k about in O. V., etc. Textbook of psychiatry, page 365, M., 1958; Kostiuk P. G. Structure and function of the descending systems of a spinal cord, L., 1973; Magnus R. Installation of a body, the lane with it., M. — L., 1962; The Principles of the system organization of functions of the Organism, under the editorship of P. K. Anokhin, page 242, M., 1973; System mechanisms of activity of athletes, under the editorship of Tsarapkin, Volgograd, 1980; The Statistical electrophysiology, under the editorship of E. V. Na-rushevichusa and A. D. Smilgevichus, the p. 2, page 10, Palanga, 1968; Martin J. River of A short essay on posture and movement, J. Neurol., Neurosurg., Psychiat., v. 40, p. 25, 1977; Prost J. H. Varieties of human posture, J. Mammal., v. 55, p. 1, 1974; Rademaker G. G. Die Bedeutung der roten Kerne und iibrigen Mit-telhirns fiir Muskeltonus, Korperstellung und Labyrinthreflexe, B., 1926; Sherrington Ch. The integrative action of the nervous system, Cambridge, 1947.

L. A. Kukuyev; V. A. Polyantsev (physical.).