Projection Fibers

Projection fibers

Projection fibers are nerve fibers that connect the cells of the cerebral cortex with the cells of the lower parts of the brain and/or spinal cord. They play an important role in transmitting information between different parts of the central nervous system and are an integral part of information processing in the brain.

There are about 14 billion projection nerve fibers in the human body, and they perform many functions. For example, they provide communication between the brain and other organs and systems such as the eyes, ears, skin, muscles and internal organs. Projection fibers are also involved in the regulation of many processes, such as breathing, heartbeat, digestion, etc.

In addition, projection fibers can be damaged in various diseases, such as stroke, multiple sclerosis, Parkinson's disease and others. This can lead to a disruption in the transmission of information between parts of the brain and cause various symptoms such as loss of sensation, movement disorders, etc.

Thus, projection fibers play an important role in the functioning of the central nervous system. Understanding their role and mechanisms of operation can help in the development of new treatments for diseases associated with impaired transmission of information between different parts of the brain.

Projection fibers are nerve fibers that connect the cells of the cerebral cortex with the underlying parts of the spinal cord.

Main groups of nerve fibers. They are processes of neurons, i.e., they are characterized by the same structural features. Any fiber has a cell body (axon), dendrites (vetviaxon) and a myelin sheath covering it. The latter promotes the exchange of substances and electrolytes, prevents compression and damage to the processes. At the apical (tip) end, the body of the neuron is connected to the processes of other neurons through specialized devices - synapses. Their main function is the transmission of excitation from one nerve cell to another. There are two types of contacts between neurons - those in which there is a direct effect on cellular structures (synapses) and intercellular contacts. The latter have a characteristic “club” shape, with the help of which they are connected to the corresponding part of the body of another cell. The first type of contact does not occur often. Most characteristic of motor nerve cells of the subcortical nuclei of the digestive and other systems. Here, the functional significance of nerve fibers and their high conductivity (the ability to conduct a nerve impulse) leads to their connection by direct mechanical means.

Projection nerve fibers are formed in all parts of the central nervous system, but mainly in the brain stem (with the exception of the cranial parts of the vagus nerves), forming pathways for the transmission of excitations in a certain direction. Some of them can cover significant lengths of the nervous tract (the so-called ascending pathways), while others ensure the transfer of excitation from the central nervous system to the working organs (centripetal, centripetal-radial). The set of the latter is called sensory pathways, the path from which is transmitted to the primary area where information is processed by the central nervous system. (For example, the parasympathetic centers of the spinal cord are located in the posterior plexus and innervate the kidneys, intestines, and uterus). Along with the above, there are also paths that transmit excitation in the opposite direction from the centers to the working organs (descending). Directed from the lower parts of the central nervous system, they arise in a single modality - all the efferent fibers of the autonomic networks and some signals from the muscles, liver, intestines, etc. converge here. Thus, the fibers of the ankle and gluteal nerves contain a large number of autonomic fibers, and many spinal arteries contribute to their development. To the same education