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 body functions. The cavity of the cranial region, which contains the medulla, protects the bones from external mechanical influences. The brain, as well as the spinal cord, is covered with three membranes: hard, soft and arachnoid, each of which performs its own functions.
Structure of the hard shell of the brain
The strong hard shell of the brain is a dense periosteum of the skull, with which it has a strong connection. The inner surface of the shell has several processes penetrating into the deep brain fissures in order to separate the departments. The largest such process is located between the two hemispheres, being a kind of sickle, the posterior part of which fuses witha hint 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, through which venous blood is drained.
Structure of the arachnoid membrane of the brain of the head
The arachnoid shell of the brain is located on the inside of the hard shell. Although it is very thin and transparent, it does not penetrate into the fissures and furrows of the hemispheres, while covering the entire surface of the medulla and passing from one part to another. The arachnoid is separated from the choroid of the brain by the subarachnoid space, which is filled with cerebrospinal fluid. Where the membrane is located above deep and wide furrows, the subarachnoid space becomes wider, forming cisterns of various sizes. Above the convex parts, especially above the convolutions, the soft and arachnoid membranes of the brain are closely pressed against each other, so the subarachnoid space in these areas is significantly narrowed and is a capillary gap.
Names of large subarachnoid cisterns:
- cerebellar sinus is located in the depression between the cerebellum and the place where the medulla oblongata is located;
- the sinus of the lateral fossa is located onlower lateral side of the cerebral hemisphere;
- cistern of chiasma functions at the base of the brain of the head, from the front of the optic chiasm;
- localization of the interpeduncular cistern - between the legs of the brain in the interpeduncular fossa.
The membranes of the brain are connective tissue structures that also cover the spinal cord. They perform the function of protection, creating histohematic, cerebrospinal fluid and cerebrospinal fluid barriers, which are related to metabolic processes and the outflow of cerebrospinal substance. Without these structures, the normal functioning of the brain and the sufficient supply of all vital substances to it are impossible.
