Red nucleus (part of the brain): what it is, characteristics and functions

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 performs are known, it is still a partially unknown structure, and it is still being investigated today. In this article we will learn about the best-known functions, their characteristics, and the effects it produces in case of injury.

• Related article: "Parts of the human brain (and functions)"

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.

tegmentum

The tegmentum is a brain area located in the brainstem, formed by 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 (also related to movement) and the

brain peduncles (which coordinate eye movements with the head and neck).

At the same time, the red nucleus is divided into two zones: the paleorubrum and the neorubrum. It has two parts, a magnocellular lower portion and a parvocellular upper portion.

• You may be interested in: "Midbrain: characteristics, parts and functions"

Functions of this part of the brain

the red core intervenes in the control of muscle tone, and inhibits muscle contraction responsible for tone. In addition, it participates in the 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 part of the arm.

Another of the functions of the red nucleus is that it participates in the crawling of babies, when they learn to do it. Besides, is responsible for the swinging motion of the arms when we walk. Even certain hand movements are also partially controlled by the red core.

On the other hand, the red nucleus acts as a relay center for cerebellar and striatal reflex pathways, and has an important role in cortical extrapyramidal pathways.

in animals

It is known that in animals that do not have a major corticospinal tract (involved in the control of voluntary movements), the red nucleus is involved in their gait. In addition, it is believed that some animals other than humans use this brain structure more. This is due to in humans the corticospinal tract is more dominant.

Characteristics and anatomy

The color of the red nucleus is a pinkish 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 of the midbrain., which extends from the black substance (related to the synthesis of dopamine) 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 via axons.

However, while some things are known, much of the function of the red nucleus in humans is unknown.

Related structures

There is another structure related to movement and 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 core, which has more control over the hands.

Fine psychomotricity (fine control of the fingers), for its part, depends on another related structure, the corticospinal tract, related to specific and voluntary movements. The axons of the red nucleus (the majority) do not project to the spinal cord, but do transmit information to the cerebellum, coming from the motor cortex.

• Related article: "Human cerebellum: its parts and functions"

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 tegmental lesion may also include the red nucleus; in these cases, motor skills are altered. Some symptoms that may appear are involuntary tremorsespecially in the hands and arms.

motor disorders

The lesion of the brain areas responsible for controlling, coordinating and managing movements (in addition to the red nucleus), entails a series of important motor disorders. However, the causes that originate this type of disorder are very varied and can go beyond what was initially discussed.

There are two types of motor disorders: pyramidal (involving paralysis) and extrapyramidal (involving difficulties or alterations in the efficiency of movement). At the psychological level, the latter are the ones that have more to do with the field of neuropsychology.

extrapyramidal disorders

In extrapyramidal disorders there is interference in the execution of movements and reflexes. This can translate into a loss in the fluidity 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, convulsions, dystonia, dyskinesia, akathisia, 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) of the neostriatum, and with lesions in the subthalamic nucleus.

Bibliographic references:

• Carlson, N.R. (2005). Behavioral physiology. Madrid: Pearson Education.
• Del Abril, A; Caminero, AA.; Ambrose, E.; Garcia, C.; by Blas M.R.; dePaul, J. (2009) Fundamentals of Psychobiology. Madrid. Sanz and Torres.
• Felten, D.L.; Shetten, A.N. (2010). Netter. Atlas of Neuroscience (2nd edition). Barcelona: Saunders.
• Netter, F. (1989). Nervous system. Anatomy and physiology. Barcelona: Salvat.