Let's talk in this article about the striopallidar or pallidostrial system, its physiology, functions, lesion syndromes and other important features and characteristics. Let's start with the definition of the concept.
What is the striopalidar system?
Striopallidarnaya - the word comes from lat. (corpus) striatum - "striped (body)" and (globus) pallidus - "pale (ball)". This system is part of a larger extrapyramidal system. Includes the nuclei of the striatum, along with their efferent and afferent pathways. Its main purpose is participation in the regulation of muscle tone and coordination of movements.
The extrapyramidal system, on the other hand, combines the motor centers of the cerebral cortex, its pathways and nuclei - only those that do not pass through the pyramids of the medulla oblongata. The main function of the system is the regulation of the entire range of involuntary components of motor activity. It's musculartone, posture and movement coordination.
Anatomy of the system
Let's get acquainted with the anatomy of the striopallidary system. The striated bodies that make it up are, by their nature, considered to be the basal ganglia. These are areas of concentration of gray matter in the thickness of the white in the cerebral hemispheres. In addition to the striatum, they also include the amygdala, the fence.
The striatum itself consists of two parts - the lentiform and caudate nucleus, between which the internal capsule is enclosed. Their totality is united by the concept of "striopallidadar system". The striatal component includes the shell and the caudate nucleus, and the pale ball, respectively, belongs to the pallidar component. In the striatum, fibers terminate from four sources at once:
- thalamus;
- almygdala;
- midbrain substantia nigra;
- cortex of both hemispheres.
Thus, the striatum is connected with almost all cortical fields of the cerebral hemispheres. The striatal system is internally divided into three areas, depending on where the fibers bring information from:
- Associative is the body and head of the caudate nucleus.
- Sensomotor - this includes the shell.
- Limbic - the tail of the caudate nucleus.
Striatum and pallidum: differences
Let's consider in the summary table the main characteristics of the components of the striopallidary system.
| Striatum | Pallidum | |
| Elements | Shell, caudate nucleus,fence. | Globular globus pallidus (medial and lateral), nucleus red, substantia nigra, subthalamic nucleus of Lewis. |
| Phylogenetics | Younger. | More ancient. |
| Quantitative expression of nerve fibers and cells | A small number of fibers, but a large number of large and small neurons. | A small number of large cells, a large number of fibers. |
| Periods of functional activity and myelination |
Myelinates closer to 5 months of life. Movements become more automated, calculated, habitual as they grow up. |
It is the pale balls in the first months of life that are the motor centers of the body. Manifests itself as a series of excessive movements, fussiness, rich facial expressions. |
| Syndromes of Defeat | Hyperkinic, dystonic. | Hypokinic, hypertonic, Parkinson's syndrome, akinestic-rigid. |
Let's look at the features of the system in the process of evolution of life on Earth.
Pallidostrial system in evolution
The pale body is considered more ancient than the striatum. The system itself at that stage of evolution, when the cerebral cortex of living creatures was not quite developed, completely controlled the behavior of the animal, was its motor center.
The striopallidary locomotor apparatus made it possible to perform mass diffuse movements of the body - swimming,movement and so on. After the "reign" of the cerebral cortex, the striopallidary system passed into its subordination and began to provide training for the performance of a particular movement. At the present stage, it is responsible for the redistribution of muscle tone - the coordinated contraction and relaxation of muscle groups.
It is the striopallidar system that helps to save muscle energy during the movement, and also allows you to bring some actions to the "automatic" - driving a car, waving a mower's hand, running a musician's fingers, etc. People inherited it from birds and reptiles. In young children, at some stages of development, you can very clearly see her work:
- Pallidum (premature infants, newborns): crawling, axial movements of the body.
- Striatum (second half year of life): excessive fidgety movements, hand support reaction.
Movement training
If you look at the process of learning a particular movement from the side of the striopallidary, extrapyramidal system, then three phases can be distinguished:
- Pallidary: movements are still slow; it is noticeable that they are carried out with prolonged muscle contraction.
- Striate: movements at this stage are excessive, awkward.
- Rationalization of movement: the body gradually develops the optimal way to perform the movement - the most effective with minimal effort. This happens already under the control of the cortex.
Physiology of the system
Let's understand the physiology of the striopallidary system, let's see how itfunctioning:
- Cortical neurons excite striatal. The axons of neurons of the striatal group, in turn, end on the neurons of the pale ball - they inhibit the latter.
- The efferent tract, which ends in the thalamus, originates precisely in the inner segment of the globus pallidus.
- From the thalamus, signals go to the motor segments of the cerebral cortex. As a result, the basal nuclei are the main intermediate nucleus that connects the motor areas of the cortex with all other areas.
- Among other things, fibers also descend from the globus pallidum to the nuclei of the olive, the red nucleus, the vestibular nuclei of the roof of the midbrain - the nuclei of the brain stem.
- Nerve impulses, having overcome the path "pale ball - nuclei of the brain stem", rush to the motor neurons of the anterior horns of the gray matter of the spinal cord. The impulses have an excitatory effect on these neurons, which is designed to increase motor activity.
Now, having considered the physiology of the striopallidary system, let's move on to the essence, meanings and functions of the described processes.
Functions of the pallidostrial system
Pallidostrial structure - the center of the extrapyramidal. The main function of the striopallidary system is the regulation of all motor voluntary movements:
- creating an optimal posture for a certain action;
- achieving tone between agonist and antagonist muscles;
- proportionality and smoothness of movements.
If this system is damaged, a direct consequence will be a violation of human motor functions - dyskinesia. This can manifest itself in two extremes - hyperkinesia and hypokinesia.
Another function of the striopallidary system is that it establishes a connection between the following areas:
- cortex;
- pyramidal cortical motor system;
- musculature, formation of the extrapyramidal system;
- visual thalamus;
- spinal cord.
The pallidostrial system is an important part of the extrapyramidal and entire motor system of the body.
Pallidum syndromes
Let's start talking about the syndromes of lesions of the striopallidary system, mentioning the symptoms that indicate dysfunctions of the globus pallidus. They can be as follows:
- Catalepsy - pose of a mannequin, doll. When changing the state of rest to activity, the patient freezes in an uncomfortable position.
- The so-called alms-begging posture: bent torso, bowed head, arms brought and reduced to the torso, motionless gaze fixed on emptiness.
- The patient, unbalanced, cannot correct his posture - he is "carried" forward, backward, to the sides.
- Bradykinesia - there is inactivity, stiffness of the patient.
- The beginning of a motor act is difficult - a person marks time, performs the same type of actions several times in a row.
- Oligokinesia - povertyand expressionless movements.
- "Paradoxical kinesia" - patients with emotional arousal break out of a state of rest - they begin to run, dance, jump.
- Speech slows down, becomes quiet.
- Handwriting becomes small and fuzzy.
- The patient's thinking is visibly deteriorating.
- There is some "stickiness" in communication.
- Visible tremor at rest - movement of the head, hands.
- Sleep is disturbed.
- There is peeling of the skin, hypersalivation.
Striatal lesion syndromes
Striate symptoms include:
- Hyperkinesis - excessive movements.
- Hemiballism, ballism - the patient makes sweeping movements with his limbs, as if copying the flapping of a bird's wing.
- Athetosis - slow, frilly movements are made with both hands and feet, and facial muscles - the patient grimace, clicks his tongue, twists his mouth, protrudes his lips.
- Chorea - fast, choppy, erratic, non-rhythmic movements. The patient may wiggle his arms and legs, stick out his tongue, frown, etc.
- Dystonia - a visible bend, twisting of a part of the body. For example, with spastic torticollis, the head is unnaturally tilted to the side, may involuntarily tilt.
- Tiki - twitching of a specific muscle group.
- Myoclonus is a sharp causeless startle.
- Hiccup.
- Symmetrical facial muscle spasms.
- Professionalconvulsions - muscle spasms involved in repetitive professional movements of musicians, typists, etc.
That's all we wanted to tell about the structure, function of the striopallidary system, its physiology, and role in the evolutionary process. It is easy to guess about violations of this system by a number of recognizable syndromes.
