Tasks of the cerebral medulla
The cerebral medulla is also known as the white matter. It consists of a network of supply and support cells between which the nerve processes, the axons, run in bundles. These bundles are combined into pathways.
There are no cell bodies in the white matter. Their task is therefore to sort the nerve tracts and supply them with nutrients. Particularly large pathways are also known as fibres, as they can be seen with the naked eye when the brain is opened.
As the name suggests, they then look like fibres. Association fibres transport information within one hemisphere of the cerebrum from one cortex area to another, while commissure fibres connect the cortex areas of the two hemispheres with each other. Finally, projection fibers are distinguished, which connect nerve cores in the cortex with nerve cores in the depth of the brain.
These three groups of fibres run exclusively in the cerebrum. In addition, the cerebral medulla contains pathways that lead to the cerebellum, the brain stem, the spinal cord and the extremities, thus connecting the cerebrum with other structures of the central and peripheral nervous system. The cells that are responsible for supplying and maintaining the nerve cells in the cerebral marrow are called glial cells.
The glial cells of the central nervous system include astrocytes, oligodendrocytes, microglia and ependym cells. The astrocytes mainly serve as supporting cells and are involved in the construction of the blood-brain barrier. They thus surround blood vessels that run along the brain and prevent pollutants and toxins from entering the brain.
Oligodendrocytes surround the long axons of nerve cells. In this way, they protect the axons, supply them with nutrients and isolate them. The insulation works in a similar way to ordinary electrical cables and ensures that information is transmitted more quickly and safely along the nerve processes.
As in the rest of the body, waste products from metabolic processes are produced in the brain. These are absorbed and transported away by the microglia. Finally, there are the ependymal cells.
They form a thin layer on the cerebral cortex, separating the cortex from the liquorice spaces. The cerebrospinal fluid spaces are filled with cerebrospinal fluid, a liquid. The brain floats in this liquid. It is supplied and protected by the cerebrospinal fluid and can give off waste products to it, which are then transported into the body for disposal. The ependymal cells are therefore not strictly speaking part of the cerebral cortex, but are nevertheless counted among the supply cells of the central nervous system.
Tasks of the cerebral hemispheres and cerebral hemispheres
Although the two halves of the cerebrum look identical when viewed from the outside, they exhibit certain differences in their function. They are divided into a dominant and a non-dominant hemisphere. By definition, the dominant hemisphere is the hemisphere that processes speech in motor and sensory terms.
While sensory interpretation takes place in the Wernicke language centre, the Broca area is responsible for the formation and planning of words and sentences, i.e. the motor component of speech. Accordingly, these two areas are almost always located in the dominant hemisphere of the brain. Interestingly, the Wernicke centre is considered to be the rational language centre leading to the understanding of a language.
In contrast, the non-dominant half of the brain is the speech centre for processing non-verbal, musical auditory impressions. For left-handed people, the right hemisphere is usually the dominant one, for right-handed people it is the left hemisphere. This is because the motor and sensory functions of one hemisphere are planned and interpreted in the opposite hemisphere. In addition, the posterior parietal cortex (=rear part of the lateral cerebral cortex) only occurs on one side of the non-dominant half. This is relevant for spatial orientation.