Vestibular human analyzer. Structure and functions

The vestibular analyzer is a system of nerve structures and mechanoreceptors that allows a person to perceive and correctly orient the position of his body in space. The stimulants of mechanoreceptors are various kinds of acceleration. Angular accelerations cause excitation of ampullar receptors. The linear nature of accelerations contributes to the appearance of impulses in the sensors of the vestibule. The vestigial and ampullary impulses are transformed into neural signals and help the central nervous system maintain its orientation in space.

The structure of the human vestibular analyzer

Static reflexes are realized due to the interaction of organs capable of perceiving stimuli and transforming them into nerve impulses. Signals come from the vestibular apparatus to the vestibular nerve, through which they enter the regions of the medulla oblongata. In the run-up there are a martha and a pouch. Their The surface is covered with sensory cells, which in shape are divided into columnar and pear-shaped. The sensitive hairs of these cells are surrounded by an otolith membrane. When the head moves due to gravity, the otoliths move and act on the sensory hairs. Nerve endings are connected to the basal part of the sensor cells, which perceive signals from the hairs.

Main functions

The study of the vestibular analyzer revealed five types of reactions that they produce:

1. Vestibulosomatic reactions due to vestibulospinal ligaments. With their help the vestibular analyzer promotes the redistribution of muscle tone under various accelerations.
2. Oculomotor reactions. They are caused by the presence of eye-motor connections and cause involuntary eye movements or nystagmus. This process has a two-phase nature. In the first phase, the stimulation of the ampullar receptor occurs and the subsequent slow movement of the eyes to the side. In the second phase, as a result of rapid compensating movement, the eyeballs return to their original position. The vestibular analyzer provokes nystagmus to fix outgoing fragments of the surrounding environment during rotational movement. It also helps a person to keep track of objects that move at high speed.
3. Vestibulovegetative functions are adaptive Character. When these reactions occur, there may be an increase in heart rate, an increase in blood pressure, the appearance of nausea against the background of the acceleration action.
4. Vestibulomozzhechnye reactions are manifested during active movement. They help control the position of the body in space, when the body is in a dynamic state. This is due to the correct distribution of muscle tone at different accelerations.
5. Due to the presence of connections with the cerebral cortex, the vestibular analyzer helps to perform central control and correction of the vestibulosensory reaction.