OTOLITOVY DEVICE

From Big Medical Encyclopedia

OTOLITOVY DEVICE (grech, us, ot [os] an ear + lithos a stone) — one of receptors of balance and space feeling. Specific irritants of O. and. the rectilinear acceleration arising at the rectilinear movements of the head or all body and also a deviation of a body from a vertical, centrifugal acceleration, impact on an organism of gravitational forces (gravity) are.

Anatomy

Fig. 1. Cross section through an elliptic sack and an ampoule of the semicircular channel: 1 — a cavity of an elliptic sack, 2 — a connective tissue basis of an elliptic sack and the epithelium covering it, 3 — a spot of an elliptic sack, 4 — a ganglion of a predoor nerve, 5 — a cavity of a webby ampoule, 6 — the epithelium covering an ampoule, 7 — an ampoule comb. The rectangle designated the part of cross section shown in fig. 2; X 140. Fig. 2. Diagrammatic representation of a spot of spherical and elliptic sacks: 1 — supporting cells, 2 — voloskovy touch cells, 3 — nerve terminations, 4 — myelin nerve fibrils, 5 — static hairs, 6 — a membrane of statoconiums, 7 — otoliths.

Lake and. the person it is presented by spots of spherical and elliptic sacks (maculae utriculi et sacculi) of a webby labyrinth inner ear (see). Lake and. consists of the supporting and voloskovy (touch and epithelial) cells of a spot and an otolitovy membrane (a membrane of statoconiums, T.). Voloskovy cells on an ultramicroscopic structure are subdivided into two types: cells of the first type, the basis to-rykh it is surrounded in the form of a bowl with nerve terminations with characteristic synapses, and cells of the second type, similar the first, but poorer in nerve terminations. 60 — 80 motionless hairs and one mobile depart from tops of voloskovy cells. Hairs are turned to an otolitovy membrane (tsvetn. fig. 1 — 2). It represents the fine-fibered mass of a jellylike consistence, in to-ruyu otoliths are included (statoconiums, T.) — microscopic crystal educations from organic compounds of calcium like calcite, aragonite, gypsum, etc., shaped oblong hexagons. Calcium ions in these connections can be partially replaced with ions of magnesium, sodium, potassium, etc., but it is much less of them, than calcium ions.

The spot of a spherical sack at usual position of the head is located horizontally, and a spot of an elliptic sack (utricle) — vertically in the sagittal plane, voloskovy cells are directed lateralno from the center of the head.

Comparative anatomy

O. and. developed from body of static balance, or a static («acoustical») bubble, statocysts. At the lowest animals it is an epithelial bubble, in a wall to-rogo there are voloskovy cells, filled with the liquid containing a mobile limy little body (an otolith, statoconiums). At different animals in the course of evolution mainly the otolith changes. It can be presented by compact education (at fishes) or separate concretions — statoconiums (at amphibiouses, reptiles, mammals), to-rye contact with each other the help of an organic mukopolisakharidny basis. At backboneless animals O.'s otoliths and. on chemical structure and a structure are similar to O. and. vertebrata. It was established during the studying in the polarized light, by means of a supermicroscope and the X-ray crystallographic analysis a statocyst (receptors of gravitation of invertebrates) of coelenterates, dogstails, annelid, Crustacea, mollusks. At backboneless animals the otolith can be formed is endogenous and exogenous. Otoliths of an endogenous origin are synthesized directly in a cavity of a webby labyrinth. At the same time distinguish inside - and extracellular synthesis. At the lowest invertebrates (coelenterates and dogstails) otokoniya develop intracellularly in special cells — litotsita and otokonioblasta. The endogenous intracellular way of formation of an otolith in the course of evolution is replaced with endogenous extracellular. By an endogenous extracellular way otoliths in statocysts of mollusks and nek-ry arthropods are formed (mizid). At these animal O. and. it is synthesized in the form of otokoniya or spheroliths. Otoliths of an exogenous origin can consist of the quartz grains of sand and other foreign educations brought in a receptor of gravitation from the outside.

Physiology

Se-wall in 1883 the first began to study function O. and. fishes. J. Breuer at the end of 19 century for the first time formulated the theory of function O. and., added then R. Magnus, V. I. Voyachek, K. L. Hilovym.

According to J. Breuer, O.'s irritation and. occurs owing to the shift of an otolitovy membrane and bending of hairs of the sensory voloskovy cells connected with an otolitovy membrane under the influence of the inertial forces developing as a result of impact on an organism of the rectilinear accelerations operating in all directions. According to R. Magnus and de Klein (And. de Kleijn), maximum irritation of voloskovy cells of O. and. comes when otoliths hang, and minimum when they press on hairs. Otolitovy reflexes are shown on muscles of extremities and necks. Feature of otolitovy reflexes is their tonic long character. O.'s irritation and. cause also tonic reflexes from eye muscles — vertical deviations and rotary motions (see. Nystagmus ).

The vertical movements of eyes can be found in the person easily at impact of rectilinear accelerations from vertical movement (irritation of an elliptic sack), and the rotatorny movements of eyeglobes are observed at O.'s irritation and. spherical sack. To each position of the head in space there corresponds a certain position of eyes that is reached by the corresponding reductions of muscles. While the head is in this or that position, position of eyes does not change. Biol, sense of tonic otolitovy reflexes on muscles of eyes is that at change of position of the head, eyes, deviating to the opposite side, hold under review surrounding objects; it promotes the best orientation. As the deviation of eyes compensates the deviation of a field of vision caused by turn of the head, it is called compensatory».

Originally function O. and. considered separately from activity of receptors of semicircular channels. V. I. Voyachek, K. L. Hilov showed that O. and. and receptors of semicircular channels are functionally closely interconnected. If at irritation of semicircular channels by rotation to cause also O.'s irritation and. (to change position of the head), reflexes from semicircular channels sharply change: the nystagmus is braked, reflexes from cross-striped muscles amplify, and also vegetative reactions.

From motive otolitovy patol. reflexes the most important is asymmetry in a tonic compensatory deviation of eyes, and also patol, postural righting reflexes (see. Pose ).

Methods of a research

Assessment of a condition of O. and. it is given on the basis of a nystagmus of situation, disturbance of compensatory movements of eyes, gait and balance, existence of illusory feelings of space situation, dizziness, vegetative frustration.

For the purpose of check of a condition of O. and. to the patient suggest to incline quickly the head and a trunk since at the same time the direction of acceleration of constant force of terrestrial gravitation (gravity) changes. Besides, the patient is put on a back, a stomach, the right and left side (it is in each situation 10 — 15 sec.) and observed whether the spontaneous nystagmus or dizziness will appear. For an exception of influence of cervical muscles on from-litovye reflexes it is recommended to incline the head and a trunk at the same time. For this purpose apply a special table of Grakhe.

Patol, otolitovy reflexes on extremities come to light in a look about-makhivaniya at index test (see. Vestibulometriya ), In the beginning the patient sits directly, then test is carried out with a ducking to the right and to the left.

More objective is the research on antirotation of eyes. It is carried out by means of the special device, the Crimea is fixed normal and pathologies a deviation of eyes at a ducking in degrees. At pathology accurate asymmetry in a deviation of eyes at a ducking is observed to the right and to the left, reduction and increase in an angle of deviation of eyes. For a research of antirotation of eyes it is possible to use a method of an indirect otoli-tometriya. After O.'s irritation and. note a deviation in degrees of a consecutive visual object (is caused by light flash with passing of light through a narrow crack).

At professional selection of seamen, pilots, and especially astronauts are applied by specially developed methods of a research.

Otolitovy reaction is offered by V. P. Voyachek. The examinee blindly and the head inclined on 90 ° forward rotate in Barani's chair with a speed of 1 a turn for 2 sec.; in total make 5 turns during 10 sec. After despinning in 5 sec. to the examinee suggest to become straight. At the same time there is a reaction from cross-striped muscles in the form of protective movements and vegetative disturbances appear.

Cumulative way of a research of sensitivity of O. and., offered by K. L. Hilov, it is based on what investigated is shaken within 15 min. on a special chetyrekhshtangovy swing. Vegetative reflexes, depending on time of their emergence can result from it (15, 10, 5 and 0 minutes from the beginning of a research) distinguish 4 extents of cumulation of irritation of O. and.

Centrifugal force is an adequate irritant of O. and. At rotation in the centrifuge with removal of the head from a rotation center there is O.'s irritation and. The test defining O.'s sensitivity and., the experience of double rotation on the centrifuge developed by A. E. Kurashvili and V. G. Bazarov is. Investigated with inclined headfirst sits on the periphery of the centrifuge in Barani's chair. The centrifuge and a chair rotate at the same time; at the same time otoliths spherical, elliptic sacks are periodically irritated. Normal examinees have a feeling of driving in the cart on the jolty road.

Modern methods of inspection allowed to establish that an excitation threshold of O. and. it is less than 10 cm/sec. 2 .

Pathology

Causes of infringement of O. and. are various: acute or chronic inflammatory and noninflammatory diseases of an inner ear, traumatic and intoksikatsionny neuritis of the VIII cranial nerve, vascular, inflammatory diseases and tumors of a brain with localization patol. the center in its trunk departments (a myelencephalon, the bridge, a mesencephalon).

O.'s disturbance and. is followed in clinic: touch reaction — a peculiar dizziness in the form of false feeling of rectilinear falling, a provalyvaniye in the most various directions; vegetative reactions, napr, a condition of discomfort, disturbance of cordial activity, blanching (see. Vestibular reactions ); tonic reflexes on cross-striped muscles of a trunk, an extremity, and also on muscles of eyes.

Otolitovy dizziness arises at a certain position of the head.

Treatment first of all shall be directed to the disease which caused O.'s pathology and. A symptomatic treatment variously in acute and chronic stages of the disease which is followed by dysfunction of O. and. In an acute stage the bed rest, introduction subcutaneously 0,1% of solution of atropine (1 ml) and 2% of solution of caffeine (1 ml), intravenous injection of 40% of solution of glucose, a hot-water bottle to legs is recommended. In hron, the special gymnastics, reception of a bellaspon is shown to a stage for a training of a vestibular mechanism, at dizzinesses of vascular genesis vasodilators are recommended.

See also Vestibular analyzer .


Bibliography: Ageeva-Maykova O. G. and Zhukovich A. V. Fundamentals of otolaringo-neurology, M., 1960; Alekseeva N. S., etc. Method of assessment of a functional condition of the otolitovy device, Vesta, otorinolar., No. 5, page 41, 1980; Wynn and - to about in Ya. A. of ides of river. The structural and functional organization of a vestibular mechanism, in book: Influence of dynamic factors kosmich. flight on an organism of animals, under the editorship of A. M. Genin, page 135, M., 1979; To at r and sh in and l and A. E. and B and and V. P's yak. About a functional linkage between semicircular channels and the otolitovy device, in book: Fiziol, a vestibular analyzer, under the editorship of V. V. Larin and M. D. Yemelyanov, page 119, M., 1968; With about ldatovi.b., Sushcheva G. P. and Hrappon. C. Vestibular dysfunction, M., 1980; T and - m and r. Fundamentals of touch physiology, the lane with English, M., 1976; Hilov K. JI. Function of an organ of equilibrium and disease of movement, L., 1969; With about d at To. And. and. Nelson A.J. The effect of verticality perception on body balance in normal subjects, Phys. Ther., v. 58, p. 35, 1978; L i m D. J. Formation and fate of the otoconia, Ann. Otol. (St Louis), v. 82, p. 23, 1973; Magnus R. Korperstellung, B., 1924; Neural mechanisms of the auditory and vestibular systems, ed. by G. L. Rasmussen a. W. F. Windle, p. 247v, Springfield, 1960.


H. S. Blagoveshchenskaya; M. 3. Aronova (An.).

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