SUPPLEMENTARY MOTOR AREA AND CLINICAL PICTURE OF ITS LESION

Abstract

Methods: The supplementary motor area (SMA) is a cortical region, that is located on the medial surface of the frontal lobe entirely within the interhemispheric fissure between the primary motor cortex (PMC) and prefrontal cortex (PFC). This area is a heterogeneous region in its structure, as well as in its connections with other parts of the brain; on the basis of these differences, the pre-SMA and SMA-proper regions are distinguished in it. Numerous neural connections with other parts of the central nervous system (CNS) suggest the involvement of the SMA in many cognitive functions, and not only in higher motor ones, as previously was thought. In particular, in the dominant hemisphere, the SMA performs the speech function through the frontal oblique fascicle (FOF), a bundle of association fibers that connects the SMA with Broca's area. In the event of various pathologies affecting the SMA and after neurosurgical manipulations in this area, a variety of neurological disorders can occur both motor and verbal. With the damage of this cortical region in the dominant hemisphere, SMA syndrome (akinetic mutism) can occur. This paper provides a review of the anatomical, cytoarchitectonic, and functional features of the SMA, as well as a detailed description of the clinical picture of the lesion of this cortical region. Keywords: Brain, supplementary motor area, SMA syndrome.