Supplementary motor area

Supplementary Motor Area

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The Supplementary Motor Area is located on the medial surface of the brain's hemisphere, anterior to the primary motor cortex.

The Supplementary Motor Area (SMA) is a part of the primate brain that contributes significantly to the control of movement. It is located on the medial surface of the brain's hemisphere, anterior to the primary motor cortex. The SMA is involved in the planning and coordination of motor movements, particularly those that are complex or require coordination between both sides of the body.

Anatomy

The Supplementary Motor Area is located in the Brodmann area 6, which is on the medial aspect of the cerebral hemisphere. It is anterior to the primary motor cortex and superior to the cingulate sulcus. The SMA is divided into two distinct parts: the pre-SMA, which is located anteriorly, and the SMA proper, which is located posteriorly.

Function

The SMA plays a crucial role in the planning and initiation of motor movements, as well as in the coordination of bilateral motor activities. It is particularly involved in the control of sequential movements, and in the preparation and execution of complex motor tasks. The SMA also plays a role in motor learning, and is involved in the mental rehearsal of movements.

Clinical Significance

Damage to the Supplementary Motor Area can result in a variety of motor deficits, including apraxia, a disorder characterized by the inability to perform purposeful movements despite having the physical ability to do so. In addition, lesions in the SMA can lead to alien hand syndrome, a condition in which a person's hand appears to act independently of their conscious control.

Research

Research on the Supplementary Motor Area has contributed to our understanding of motor control and has potential implications for the treatment of movement disorders. Studies have shown that stimulation of the SMA can induce movements and that the SMA is active during the planning and execution of movements.

See Also

• Motor Cortex
• Premotor Cortex
• Motor System