Motor cortex of the brain: parts, location and functions

Greets. Smile. Kiss. Runs. Eat. All these actions have at least one aspect in common: they require some type of movement on the part of the subject to be carried out. The ability to move is essential for survival, since it allows us to react to stimuli and actually execute any type of behavior, including those necessary to allow our survival. But the movement does not happen without more, it requires some planning, coordination and precision.

At the level of the brain, this control is carried out mainly by the motor cortex of the brain, although it is also influenced and mediated by other brain structures. Throughout this article we can see what the motor area is, where it is located and what parts it is made of, as well as some of the main problems that are generated by its injury.

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

Motor cortex of the brain: location and functions

The motor or motor area of ​​the brain is called that part of the cerebral cortex whose main functions are those of allowing the generation, maintenance and termination of voluntary and conscious movements on the part of the subject.

This brain region is located in the upper and rostral part of the brain, in the back of the brain. frontal lobe, located just before the central or Rolando fissure and the somatosensory area. It is in this area where the Penfield motor homunculus, representation that indicates the parts of the cortex focused on the movement of certain muscles among which some specially innervated ones stand out, such as the hands, the tongue or the face.

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Main regions of the motor area of ​​the brain

Within the motor cortex we can find different regions, all of them of great importance when it comes to managing movement. Among them the main ones are the following.

1. Primary motor cortex

The main structure in charge of movement is the area that will generate and send the movement order to all the voluntary muscles of the body. It is the part of the brain that sends the order to the muscles to contract or tighten, generating the movement.

The primary motor cortex does not work alone, but requires information from the following areas to plan and develop movements. Beltz cells are found in the primary motor cortex, among others. These cells of great length, which will go through the spinal cord to make synapses with other motor neurons.

2. Secondary motor cortex

This area plays an important role when programming and planning the movements and the sequences to follow in order to be able to carry out the movements in a precise and coordinated way. Despite this and that the electrical stimulation of these areas can produce movement, it is not in itself the one that is dedicated to carrying them out, but rather focuses on organize movement before the primary motor can carry it out.

In order to carry out a movement, it will be necessary to act in these areas first, to later to be able to pass the information to the primary motor area and once there the order of movement. It is very connected to the association areas. Within the secondary motor area we can find two regions of great relevance.

2.1. Premotor area

Located in the motor cortex, anterior to the primary motor cortex and near Silvio's fissure, is the premotor area or cortex. This area is especially linked to the programming and guidance of movement, storing motor programs learned through experience. This also includes the movement required for speech. It usually acts on those motor responses guided by an exogenous stimulus.

2.2. Supplementary motor area

Part of the secondary motor cortex, the supplementary motor area is associated with the planning, programming and coordination in complex movements, as well as the initiation of the movement. It also participates in aspects such as the adoption of positions and it also has an influence on uncoordinated movements.

3. Drill area

In different classifications Broca's area is included within the motor areas of the brain, since allows language production and the muscle movement necessary for it. It is situated on the edge of the supplementary motor area.

• Related article: "Broca's area (part of the brain): functions and their relationship with language"

4. Association areas of the posterior parietal cortex

In some classifications this area appears as one of the motor areas, because transforms visual and other sensory information into motor instructions.

• You may be interested: "Parietal lobe: characteristics and functions"

Related problems and disorders

As we have indicated previously, the motor cortex is a brain region of great importance when it comes to being able to carry out practically any action. That is why an injury to these brain areas can have severe repercussions on the lives of patients.

One of the problems that damage or destruction of the cortex or motor area can generate is paralysis and loss of mobility, whether in a specific part of the body, in a half body or throughout the body. Hemiplegia or tetraplegia may appear. If the injury is only in one hemisphere, the paralysis will occur contralaterally: that is, if the right motor cortex is injured, it will be the left hand that will be paralyzed.

With regard to secondary motor areas, the effects of injury to them often alter the ability to perform movements in a coordinated and sequential manner. We are talking about the emergence of possible apraxia, or aphasia or dysarthria when we refer to problems in the production of the movements necessary to communicate. She can also produce agrafiaher, not being able to perform the movements necessary to write correctly, problems in the feeding or even visuals as the movement of the organs and muscles is not properly governed facials.