Supplementary motor area of the brain.

 

Supplementary motor area of the brain.

In your daily life, you perform endless actions automatically, without thinking about how you perform them and which brain structures are involved. The supplementary motor area is responsible for many of these actions.

The motor cortex is a neocortical area responsible for controlling each of our movements. It is located in the frontal lobe and consists of the primary motor cortex, the premotor cortex and the supplementary motor area.

In this article, we will focus on the latter area. We will review its components, its functions and the changes it may suffer as a result of damage or other types of impact.

Supplementary motor area

The supplementary motor area occupies the posterior third of the superior frontal gyrus and coordinates postural movements. Its nerve cells are interconnected with the spinal cord. Consequently, it plays an important role in the direct control of mobility. In fact, its activity is not only relevant for initiating actions, but also for preparing and monitoring them.

 

Electrical stimulation of this area can produce elevations of the opposite arm, deviations of the head and eyes, and bilateral synergistic contractions of the muscles of the trunk and legs. Most of these movements are described as tonic contractions of the postural type.

The supplementary motor area consists of the pre-supplementary motor area and is related to the supplementary eye field. Together, the three make up the supplementary motor complex (Nachev, Kennard & Husain, 2008). The anatomical and neurophysiological characteristics of each are completely different.

 

Compared to the primary motor areas, the supplementary motor complex exhibits greater sensitivity to tasks where the action has a broader scope and is not specified by the immediate external environment. The influence of the whole can interfere with the execution and omission of actions.

Moving the eyes, turning the head slightly, raising the arms and many other actions are connected to this area.

Functions

Simple movements are mediated by activation of the primary motor area and sensory cortex. The supplementary motor area is involved with them in the preparation, initiation and monitoring of complex movements.

Through the study of blood circulation, it has been observed that blood flow increases in the primary motor area and extends to the supplementary area during the execution of complex movements. But when the same sequence is performed only mentally, it increases blood flow only in the supplementary motor area.

The supplementary motor area (SMA) occupies the posterior one third of the superior frontal gyrus and is responsible for planning of complex movements of contralateral extremities but ipsilateral planning to a small effect.

What are the supplementary motor areas?

Supplementary motor area - Wikipedia

The supplementary motor area (SMA) is a part of the motor cortex of primates that contributes to the control of movement. It is located on the midline surface of the hemisphere just in front of (anterior to) the primary motor cortex leg representation.

Which lobe of the brain contains the supplementary motor area?

the frontal lobe

The motor cortex comprises three different areas of the frontal lobe, immediately anterior to the central sulcus. These areas are the primary motor cortex (Brodmann's area 4), the premotor cortex, and the supplementary motor area (Figure.

Vad händer när det kompletterande motoriska området skadas?

Pre-SMA har förbindelser med prefrontal cortex, insula, superior frontal gyrus (SFG), caudate nucleus, putamen och thalamus. Skador på SMA resulterar i transienta talinitieringssvårigheter och minskad talutgång (mutism.

 

 

Research conducted with functional magnetic resonance (FMR) and with positron emission tomography (PET) discovered significant participation of the supplementary motor area in the control and initiation of movement and the sequences of tasks.

The researchers also specified that this area is not just an exclusive area for movement, but a mixed sensorimotor part. But its primary purpose is motor function. This area also intervenes in:

 

Bimanual coordination.

Reception of sensory stimuli.

Retrieval and repetition of learned tasks.

Motor learning of movement sequences.

It acts as a link between the limbic system and the motor apparatus.

When this area is damaged, it is likely that certain movements that involve high speeds will be permanently affected.

Disorders

This condition is a consequence of surgery or injury to this area. Immediately afterwards it manifests as contralateral hemiplegia.

Those suffering from disturbances in the supplementary motor area show a severe reduction in contralateral spontaneous motor activity. They also experience facial paralysis and impaired spontaneous speech. In addition, involuntary movement of the extremities is common. In addition, the syndrome may be accompanied by hemiataxia, hemiapraxia, hemineglect, hyperreflexia and hypertonicity.

What is the supplementary motor area of language?

The role of the supplementary motor area for speech and ...

The supplementary motor area (SMA) is a superordinate control region for speech and language processing. The posterior/anterior dimension reflects a subdivision into articulatory versus semantic aspects of language. The SMA plays an important role for the integration of subcortical functions.

Broca's area responsible for motor speech?

Broca's area, located in the left hemisphere, is associated with speech production and articulation. Our ability to articulate ideas, as well as use words accurately in spoken and written language, has been attributed to this crucial area.

Is Wernicke's area a motor area?

Wernicke area | Definition, Location, Function, & Facts ...

Wernicke area, region of the brain that contains motor neurons involved in the comprehension of speech

Movement recovery is usually complete about eleven days after surgery. But fine motor skills may not recover until about two to six weeks later. In addition, complex tasks that require special skills, as well as movements performed at high speeds, can be permanently affected. The following long-term consequences may occur:

Changes of fine movements with the hands.

Affections in the alternating fine movements of both hands. This is especially the case for complex tasks that require quick execution or great skill.

The onset of language disorders has also been detected in cases of damage to this area. It can mean:

 

Echolalia

Paraphasias

Hypofluent language

Telegraphic language

In summary, the supplementary motor area is an important cortical area for planning, initiating and monitoring movements. Although its functions are not clearly defined and multiple roles are considered, this area is central to the continuity of complex actions and to the coordination of manual movements

 

Sincerely, Samuel