Divisions of the brain. Medulla. Structure, functions, consequences of defeat

The cerebral cortex is anatomically represented by a plate of gray matter lining the outer part of the hemispheres. Its folded structure is caused by a large number of furrows separated by grooves. Most of the cortex is located deep in the furrows, and a smaller part is located on their surface. In the hemisphere, a convex (external) and internal surface is distinguished, as well as a base. On the external surface, the parietal lobe is separated from the frontal by means of a powerful "Roland" sulcus. Below it is the "sylvian" furrow, with which the temporal lobe separates from the frontal and parietal. The dark-occipital furrow separates the occipital lobe.

The microscopic structure of the cortex includes a number of fibrous and cellular layers and refers to a six-layered type of structure.

The following layers are defined:

- External granular;

- internal granular;

- molecular;

- polymorphic cells;

- Large pyramidal cells;

- medium and small pyramidal cells.

The structure and functions of the medulla oblongata, the consequences of its defeat

Its length is of the order of twenty-eight millimeters, and the width, gradually increasing, reaches twenty-four millimeters. The oblong brain continues in the cranial cavity of the spinal cord, through the central spinal canal. In its substance there is the presence of individual accumulations of gray matter, which form the nuclei of the nerves of the skull. In the formation of white matter , fibers of the conducting paths participate. The medulla oblongata contains nuclei from which the roots of the important cranial nerves come out (wandering, sublingual, glossopharyngeal, accessory). In addition, the nuclei participate in such reflex processes as chewing, swallowing, sucking, sneezing, vomiting and separation of digestive juice. The formation of nuclei in humans occurs during development within the womb of the mother. The medulla oblongata of the newborn (along with the bridge) has a weight of about eight grams. Maturation lasts an average of seven years.

By passing through the medulla oblongata centripetal and centrifugal impulses are carried out. One of the most important ways is the pyramid path. It connects the motor area in the cerebral cortex and the motor cells of the anterior spinal horns. On the border of the dorsal and oblong sections, there is a cross in the pyramidal pathways. This explains the functional disruption of the work of these or other parts of the brain when they are damaged. Thus, for example, a lesion in a pyramidal bundle above the intersection causes hemiplegia on the side of the body opposite from the focus. With simultaneous damage to the cranial nerves, functional disorders occur on the body of the same name.

The "cerebellar angle" performs the connective function. Located in the posterior fossa of the skull, it is the junction of the bridge, cerebellum and medulla oblongata. If there are tumors in this place, the nearest parts of these sections are squeezed.

In the medulla oblongata the most important centers of life support are located, which gives special importance to this department in the central nervous system. Here are the cardiovascular and respiratory centers. That is why the damage (even minor) and especially the removal of the medulla oblongata leads to death, as a result of stopping breathing and stopping the activity of the cardiovascular system.

Damage to the pyramidal pathway can lead to various consequences. It all depends on the size of the injury and the time that has passed since its inception. In many cases, such damage causes a person to have severe paralysis within one or two weeks.