The middle brain - the location and anatomical structure, the functions and features

One of the departments of the large brain is the smallest part of it - the middle brain( mesencephalon), represented in the form of four "hills", in which the nuclei that perform the function of the centers of vision and hearing are the conductor of their signals."Kholmiki" mesencephalon are a key part in the processing of information perceived by the senses.

What is the middle brain

There is a gray matter between the bridge and the intermediate brain, about 2 cm in length and 3 cm in width, representing the second upper( superius) visual wire center. The core of the medial auditory analyzer is also located there, which separated, became a separate structure for the most ancient people and is necessary for better transmission of signals from the sensory organs to the final auditory centers.

Location

The nucleus mesencephalon, the variolium bridge and the medulla oblongata form the most important structure - the trunk of the large brain, which is the continuation of the dorsal.

The stem part was located in the canal of the first, second cervical vertebra and partially in the occipital fossa. The complex of neurons is sometimes treated not as a separate independent part, but as a longitudinal interlayer or a tubercle of the brain substance between the variolium bridge and the intermediate brain.

The structure of the midbrain

The sternal part passes through the conduction pathways connecting the cortex of the cerebral hemispheres with the neurons of the spinal cord and the trunk in which the following subcortical primary centers of the visual analyzer are isolated:

• ;
• subcortical primary centers of the auditory analyzer;
• all the conductive pathways connecting the nuclei of the cerebral hemispheres with the spinal cord;
• complexes( bundles) of white matter, providing direct interaction of all parts of the brain. Based on this, the mesencephalon consists of two main parts: the tire( or roof), which contains the primary subcortical centers of hearing and vision, the legs of the brain with interstitial space, representing the pathways. The most important component is the Sylvia water pipeline - the channel connecting the cavity of the third ventricle with the fourth sinus.

  The water pipe from all sides surrounds the gray and white central substance. The gray matter contains the reticular formation, the nucleus of the cranial nerves. At the site of the passage of the aqueduct into the fourth ventricle, a brain sail is formed( in Latin velum medullare).On the lateral sections of the Sylvians, the water pipe looks like a triangle or a narrow slit and acts as an orientation element, which helps to mark the location of the brain departments on X-rays.

  Roof

  The plate of quadruple or the roof of the midbrain represents two pairs of tubercles - upper and lower. Between them lies a large crevice-subpineal triangle. From all the tubercles in the direction of the neurons of the large hemispheres, bunches of fibers or cranked bodies leave. The first pair of hills are primary visual centers, and the second - primary auditory centers.

  Feet

  Two thick strands, originating from under the varioly bridge, are called legs. Several groups of sensitive nerve cells are placed in them together with motor neurons. In the brain substance, black and red formations are distinguished, which regulate arbitrary, involuntary movements of fibers of the striated muscle tissue.

  Red nuclei

  Structure that directly regulates the coordination of all voluntary movements of a human being on a par with cerebellar neurons. Red nuclei consist of two parts: small-cell, which is the basis of the conductive pathways, and also the large-cell nucleus, which forms the basis of the nuclei. Located in the upper tire near the black substance, they represent the main pyramidal centers of motor activity - the main part of the brain that controls all the conscious and reflex movements of the human body.

  Black substance

  The location of the black substance in the form of a crescent - between the tire and legs. The substance contains a lot of pigment melanin, which gives the substance a dark color. Belongs to the extrapyramidal motor system, regulates predominantly muscle tone and how automatic movements will be performed. The peculiarity of the brain substance is that if a black substance does not fulfill its function for some reason, then the red core of the midbrain takes over.

  Functions of the midbrain

  For a long time, nuclear networks have been attributed to only one function in anatomy - the separation of the trunk and the cerebral hemispheres. In the course of further research it became clear that they perform almost all the functions inherent in highly differentiated nervous tissue, they are the point of intersection of most sensitive nerve tracts. The following functions of the human midbrain are distinguished:

  1. Regulation of the physiology of the motor reaction to a strong external stimulus( pain, bright light, noise).
  2. Function of binocular vision - providing the ability to see a clear image with two eyes at the same time.
  3. The reaction in the organs of vision, which is vegetative, is manifested by accommodation.
  4. Reflexes of the midbrain providing simultaneous rotation of the eyes and head to an external stimulus of any strength.
  5. Center for brief processing of the primary sensory, sensitive signal( sight, hearing, smell, touch) and its further direction to the main centers of analyzers).
  6. Adjustment of conscious and reflex tone of skeletal muscles, allowing arbitrary muscle contractions.

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