A part of the midbrain that is linked to the control of certain body movements.
The red nucleus is a very specific structure of the brain related to movement, very prominent, and made up of a large group of nerve cells.
Although some of the functions it carries out are known, it is a structure that is still partially unknown and is still being investigated today. In this article, we will learn about the best known functions, their characteristics and the effects that it produces in case of injury.
What is the red nucleus of the brain?
This nucleus is part of the tegmentum. The tegmentum, for its part, is located in another larger area, the midbrain. And the midbrain, in turn, is part of the brainstem or brain stem.
The tegenthum is a brain area located in the brain stem, made up of 5 structures, including the red nucleus.
Specifically, it is made up of: the periaqueductal gray matter (related to defense behavior and pain inhibition), the ventral tegmental area (related to reinforcement), the red nucleus (related to movement), the Black Substance (related to also with movement) and cerebral peduncles (which coordinate eye movements with the head and neck).
In turn, the red nucleus is divided into two zones: the paleorubrum and the neorubrum. It has two portions, a lower magnocellular and an upper parvocellular.
Functions of this part of the brain
The red nucleus is involved in the control of muscle tone, and inhibits the muscle contraction responsible for tone. In addition, it participates in motor control of the distal muscles of the arm and the proximal muscles of the legs. On the other hand, it participates in the motor coordination of the shoulder and the upper arm.
Another function of the red nucleus is that it participates in the crawling of babies, when they learn to do so. In addition, it is responsible for the swinging movement of the arms when we walk. Even certain movements of the hand are also partially controlled by the red nucleus.
On the other hand, the red nucleus acts as a relay center for cerebellar and striated reflex pathways, and plays an important role in cortical extrapyramidal pathways.
It is known that in animals that do not have an important corticospinal tract (involved in the control of voluntary movements), the red nucleus intervenes in their way of walking, and it is believed that some animals other than humans use this brain structure more. This is due to the fact that in humans the corticospinal tract is more dominant.
Characteristics and anatomy
The color of the red nucleus is a pink color that can be seen in fresh brain samples. Furthermore, as we have seen, it is made up of a large group of cells (a kind of mass).
This mass of cells is located in the area of the midbrain tegmentum, which extends from the substantia nigra (related to dopamine synthesis) to the cerebral aqueduct (which contains cerebrospinal fluid). More specifically, it is located dorsally to the substantia nigra. Within it is a rubrospinal tract, which crosses the nucleus itself through axons.
However, even knowing some things, much of the functioning of the red nucleus in humans is unknown.
There is another structure related to movement and to the red nucleus, the rubrospinal tract (fibers that originate in the red nucleus). This is more specialized in the movement of large muscles (such as the arms), unlike the red nucleus, which has more control over the hands.
Fine motor skills (fine control of the fingers), on the other hand, depends on another related structure, the corticospinal tract, related to specific and voluntary movements.The axons of the red nucleus (mostly) do not project to the spinal cord, but they do transmit information to the cerebellum, which comes from the motor cortex.
Injury and related disorders
What happens if the red nucleus of the brain is injured? Muscle hypertonicity (increased muscle tone) could appear, causing body rigidity.
A lesion in the tegmentum can also include the red nucleus; in these cases, motor skills are impaired. Some symptoms that may appear are involuntary tremors, especially in the hands and arms.
Damage to the brain areas responsible for controlling, coordinating and managing movements (in addition to the red nucleus), leads to a series of important motor disorders. However, the causes of this type of disorder are very varied and can go beyond what was initially commented.
There are two types of motor disorders: pyramidal (involving paralysis) and extrapyramidal (involving difficulties or alterations in the efficiency of movement). On a psychological level, the latter are those that have more to do with the field of neuropsychology.
In extrapyramidal disorders there is interference in the execution of movements and reflexes. This can translate into a loss in the fluency and efficiency of motor activities.
In turn, extrapyramidal disorders can be of three types:
- Rhythmic: tremors.
- Non-rhythmic and stereotyped: tics and stereotypes.
- Non-rhythmic and non-stereotyped: spasms, seizures, dystonias, dyskinesias, akathisias, etc.
These disorders are related to damage to some areas of the brain, such as the basal ganglia. They are also closely related to dopamine (deficits of this substance) in the neostriatum, and to lesions in the subthalamic nucleus.
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