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 by defining the concept.
What is a striopalid system?
Striopallidarnaya - the word came from lat. (corpus) striatum - "striped (body)" and (globus) pallidus - "pale (ball)". This system is part of a larger extrapyramidal. It includes the nuclei of the striatum, together with their efferent and afferent paths. Its main purpose is to participate in the regulation of muscle tone and coordination of movements.
The extrapyramidal system 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. This is muscle tone, coordination of posture and movement.
System anatomy
Let's get acquainted with the anatomy of the striopallidar system. The striped bodies that make up it are, by their nature, considered basal nuclei. These are areas of gray matter concentration in the thickness of white in the cerebral hemispheres. In addition to the striped bodies, they also include the amygdala, the fence.
The striatum itself consists of two parts - the lenticular and caudate nucleus, between which the inner capsule is enclosed. Their combination is united by the concept of "striopallidadar system". The shell and caudate nucleus belong to the striatal component ; to the pallidar, respectively, is a pale ball. In the striatum, fibers from four sources end immediately:
- visual tubercle ;
- amygdala;
- black matter of the midbrain;
- the cortex of both hemispheres.
Thus, the striatum is associated with almost all cortical fields of the cerebral hemispheres. The striatal system within itself is 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 nucleus caudate.
Striatum and Pallidum: Differences
Consider in the summary table the main characteristics of the components of the striopallidar system.
| Striatum | Pallidum |
| Items | Shell, caudate nucleus, fencing. | Pale balls (medial and lateral), red nucleus, black substance, Lewis subthalamic nucleus. |
| Phylogenetics | Younger. | More ancient. |
| Quantification 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 | Myelinizes closer to the 5-month period of life. As they grow older, they become more automated, prudent, familiar. | It is the pale balls in the first months of life that are the motor centers of the body. It manifests itself as a series of excessive movements, fussiness, rich facial expressions. |
| Lesion syndromes | Hyperkinetic, dystonic. | Hypokinic, hypertonic, Parkinson's syndrome, acinestic-rigid. |
Let's look at the features of the system in the process of evolution of life on Earth.
Pallidostrial system in evolution
A pale body is considered more ancient than a striped one. The system itself at that stage of evolution, when the cerebral cortex of living beings was not quite developed, completely controlled the behavior of the animal, was its motor center.
The striopallid motor apparatus made it possible to make massive diffuse body movements - swimming, movement, etc. After the "accession" of the cerebral cortex, the striopallidar system became subordinate to it and began to provide preparation for the execution of a particular movement. At the present stage, she is responsible for the redistribution of muscle tone - coordinated contraction and relaxation of muscle groups.
It is the striopallidar system that helps to save muscle energy during movement, and also allows you to bring some actions to the “machine” - driving a car, sweeping the hand of a mower, running the fingers of a musician, etc. People inherited it from birds and reptiles. In young children at some stages of development, you can very clearly notice its work:
- Pallidum (preterm infants, newborns): crawling, axial movements of the body.
- Striatum (second half of life): excessive fussy movements, the reaction of the support of the handles.
Motion training
If you look at the process of learning this or that movement from the striopallidar, extrapyramidal system, then three phases can be distinguished:
- Pallidary: the movements are still slow; it is noticeable that they are carried out with prolonged muscle contraction.
- Striatal: movements at this stage are excessive, awkward.
- Rationalization of movement: the body gradually develops an optimal way to perform movement - the most effective with minimal effort. This happens already under the control of the cortex.
System physiology
We will understand the physiology of the striopallidar system, see how it functions:
- Cortical neurons excite striatal. The axons of the 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 pale ball.
- From the thalamus, the signals go to the motor segments of the cerebral cortex. As a result, the basal nucleus is the main intermediate nucleus that connects the motor sections of the cortex to all other sections.
- Among other things, fibers also descend from the pale globe to the olive kernels, the red nucleus, the vestibular nuclei of the midbrain roof - the nuclei of the brain stem.
- Nerve impulses, having overcome the path "pale ball - the nucleus of the brain stem", rush to the motor neurons of the anterior horns of the gray matter of the already spinal cord. Impulses have an exciting effect on these neurons, which is designed to increase motor activity.
Now, having examined the physiology of the striopallidar system, we turn to the essence, meanings, and functions of the described processes.
The functions of the pallidostrial system
Pallidostrial structure is the center of extrapyramidal. The main function of the striopallidar system is the regulation of all motor voluntary movements:
- creating an optimal pose for a particular action;
- achievement of tone between muscle agonists and antagonists;
- proportionality and smoothness of movements.
With the defeat of this system, a direct result will be a violation of the motor functions of a person - dyskinesia. This can occur in two extremes - hyperkinesia and hypokinesia.
Another function of the striopallidar system is that it establishes a connection between the following areas:
- cortex;
- pyramidal cortical motor system;
- muscle, extrapyramidal system formation;
- visual tubercle;
- spinal cord.
The pallidostrial system is an important part of the extrapyramidal and the entire motor system of the body.
Pallidum Syndromes
We begin to talk about the syndromes of the striopallidar system, mentioning the symptoms indicating dysfunctions of the pale ball. They may be as follows:
- Catalepsy - pose of a mannequin, dolls. When the state of rest changes to activity, the patient freezes in an uncomfortable position.
- The so-called pose of begging for alms: a bent torso, a bowed head, arms brought down to the torso, a fixed look fixed on the void.
- The patient, unbalanced, cannot correct his posture - he "brings" forward, backward, to the sides.
- Bradykinesia - there is inactivity, stiffness of the patient.
- The beginning of a motor act is given with difficulty - a person stomps on the spot, performs the same type of action several times in a row.
- Oligokinesia - poverty and inexpressiveness of movements.
- "Paradoxical kinesia" - patients with emotional excitement break away from a state of rest - begin to run, dance, jump.
- Speech slows down, becomes quiet.
- Handwriting turns into shallow and fuzzy.
- The patient’s thinking is noticeably worse.
- There is some “stickiness” in communication.
- Visible tremor at rest - movement of the head, hands.
- Sleep patterns are disturbed.
- There is peeling of the skin, hypersalivation.
Striatal Syndromes
Striatal symptoms include:
- Hyperkinesis is excessive movement.
- Hemiballism, ballism - the patient makes sweeping movements of the limbs, as if copying the flap of a bird's wing.
- Athetosis - slow, elaborate movements are made with both hands and feet, and facial muscles - the patient grimaces, snaps his tongue, twists his mouth, and protrudes his lips.
- Chorea - fast, choppy, erratic, irregular movements. The patient can bang with arms and legs, stick out his tongue, frown, etc.
- Dystonia is a visible bend, twisting of a part of the body. For example, with a spastic crank, the head is unnaturally tilted to the side, it can involuntarily tilt.
- Tics - twitching of a specific muscle group.
- Myoclonus is a sharp causeless tremor.
- Hiccups.
- Symmetric spasms of the facial muscles.
- Professional cramps - muscle cramps involved in repetitive professional movements of musicians, typists, etc.
That's all we wanted to tell about the structure, function of the striopallidar system, its physiology, and its role in the evolutionary process. It is easy to guess about the malfunctions of this system from a number of recognizable syndromes.