The extrapyramidal system - together with the pyramidal system - supervise the course of various movements performed by us. In everyday life, we do not realize how important the functioning of the extrapyramidal system is, but this structure is responsible for improving the course of our movements - it is responsible for the fact that we can simply perform certain movements automatically. What other functions does the extrapyramidal system perform and what is its structure?
The extrapyramidal systemhas many other names - subcortical system, striatal motor system, Latin.systema extrapyramidale , English extrapyramidal system) It would seem that activities such as typing on a computer keyboard or reaching for a glass of water are not very complicated and that it is not necessary to involve many different components of the nervous system. Yes, however, definitely, but it is definitely not: in fact, even the smallest movement that we undertake - before it is performed - is necessary for the cooperation of centers located in the central nervous system, as well as structures belonging to the peripheral nervous system and effector organs, such as, for example, muscle cells.
Every day we make exceptionally different movements and some of them require our concentration, while others we perform in a certain way automatically. The extrapyramidal system is responsible for coordinating the course of the latter movements.
Extrapyramidal system: structure
The extrapyramidal system is also called the subcortical or striatal locomotor system. The structures that belong to it are located within the hemispheres of the brain and are mainly:
- striatum (consisting of the caudate nucleus and the shell)
- pale knob
- nuclei of the thalamus, this is the anterior ventral, median-medial and lateral ventral nucleus
- red nucleus
- black creature
- low thalamus nucleus
- cortex of the brain, more precisely the pre-motor cortex of the frontal lobe corresponding to Brodman fields 6 and 8
All the above-mentioned parts of the extrapyramidal system have numerous connections with each other, thanks to which these structures can perform their functions properly - it is generally mentioned that the subcortical system works thanks to numerous loopsneuronal. Examples of connections that are part of the extrapyramidal system are the connections between the thalamic nuclei and the cerebral cortex, the pathways between the substantia nigra and the striatum, and the connections between the pale and thalamic nuclei.
Extrapyramidal system: functions
Both the mentioned parts of the nervous system - i.e. the pyramidal and extrapyramidal systems - are necessary for the movements we plan to perform to run smoothly and precisely. These structures, however, have different functions - the pyramid system is responsible for controlling the course of such movements that require focus from us. When we perform an activity for the first time - e.g. we debut on a bicycle and are just learning to pedal - the pyramid system is responsible for controlling the course of such movements, while the subcortical system does not play too much of a role in this case. It is different when we cover the next hundred kilometers on a bicycle - in this case, we do not think about what exactly needs to be done with the legs to move on this vehicle and we have this possibility thanks to the extrapyramidal system.
Looking at the above, there is no need to convince anyone that the function of the extrapyramidal system is extremely important. After all, it is thanks to him that we are able to drive a car and focus on the signs on the road, and not to think about how to change gears or pick up a pen and write without considering how to accurately catch this device and how to draw from it. using the correct letters.
Extrapyramidal system: symptoms of damage
When there is any damage to the extrapyramidal system, the patient begins to experience various involuntary movements. These can be:
- choreographed movements (these are fast, voluminous, independent movements of e.g. limbs)
- torsion movements (twisting movements)
- athetotic movements (slow movements resulting in an unusual position of the patient, e.g. his fingers)
- ballistic movements (ballism - jerky movements that usually involve limbs and are compared to throwing limbs out in front of you)
- myoclonus (quick, sudden bursts of muscles)
- tremors (movements of small amplitude, i.e. small deflections)
- tics (involuntary, short movements, which can be e.g. eyelid blinking or wrist lifting)
Extrapyramidal system: diseases
Problems that can lead to damage to the structures of the subcortex and the occurrence of the above-mentioned involuntary movements are relatively numerous. The mostParkinson's disease is probably known from diseases of the extrapyramidal system.
In addition to it, the dysfunction of the subcortical structures is also clearly visible in the course of Huntington's disease, hepatolenticular degeneration and various types of dyskinesias.
About the authorBow. Tomasz NęckiA graduate of the medical faculty at the Medical University of Poznań. An admirer of the Polish sea (most willingly strolling along its shores with headphones in his ears), cats and books. In working with patients, he focuses on always listening to them and spending as much time as they need.