The human brain is an organ of the central nervous system, which consists of a huge number of interconnected processes of nerve cells and is responsible for all the functions of the body. The cavity of the cranial section, which contains the brain substance, protects bones from external mechanical influences. The brain, as well as the spinal cord, is covered with three membranes: hard, soft and spider, each of which performs its own functions.
The structure of the hard shell of the brain
The solid, hard membrane of the brain is a dense periosteum of the skull, with which it has a strong connection. The inner surface of the membrane has several processes penetrating into the deep cerebral fissures in order to separate the departments. The largest such process is located between the two hemispheres, which is a kind of sickle, the posterior part of which fuses with the outline of the cerebellum and limits it from the occipital lobes. On the surface of the dense shell of the brain there is another process that is located around the Turkish saddle, forming a kind of diaphragm and protecting the pituitary gland from excessive pressure of the brain mass. In the corresponding areas there are special sinuses, called sinuses, along which venous blood flows.
The structure of the arachnoid of the brain
The arachnoid membrane of the brain is located on the inside of the hard membrane. Although it is very thin and transparent, however, the hemispheres do not penetrate into the fissures and grooves, covering the entire surface of the medulla and passing from one part to another. The subarachnoid space, which is filled with cerebrospinal fluid , separates the arachnoid from the choroid of the brain . Where the sheath is located above deep and wide furrows, the subarachnoid space becomes wider, forming various sizes of tanks. Above the convex parts, especially above the convolutions, the soft and arachnoid membranes of the brain are closely pressed against each other, therefore, the subarachnoid space in these areas significantly narrows and is a capillary gap.
Names of large subarachnoid tanks :
- cerebellar sinus located in the recess between the cerebellum and the place where the medulla oblongata is located;
- the sinus of the lateral fossa is located on the lower lateral side of the cerebral hemisphere;
- the cross tank operates at the base of the brain of the head, from the front of the visual cross;
- localization of the intersternal cistern - between the legs of the brain in the intersternal fossa.
The membranes of the brain act as connective tissue structures that also cover the spinal cord. They perform the function of protection, creating histohematological, cerebrospinal fluid and cerebrospinal fluid barriers that are related to metabolic processes and the outflow of cerebrospinal substance. Without these structures, the normal functioning of the brain and the sufficient entry into it of all vital substances are impossible.