The motor cortex is an area within the brains cerebral cortex that is involved in the planning, control, and execution of voluntary movements. It is located in the frontal lobe and works with other brain areas and the spinal cord to translate thought into physical motion. The motor cortex comprises three different areas of the frontal lobe: the primary motor cortex, the premotor cortex, and the supplementary motor area.
The primary function of the motor cortex is to generate signals to direct the movement of the body. The primary motor cortex, situated in Brodmann area 4, sends most electrical impulses coming out of the motor cortex, and these fibers directly synapse with motor neurons of the spinal cord. The premotor cortex, situated just anterior to the primary motor cortex in Brodmann area 6, prepares for movement, especially proximal musculature. The supplementary motor area, located in the medial surface of the longitudinal fissure, just anterior to the leg representation in the primary motor cortex, is involved in body postural stabilization and coordination.
The primary motor cortex is critical for initiating motor movements, and the areas of the primary motor cortex correspond precisely to specific body parts. Many neurons in the primary motor cortex are selective for a particular direction of movement, and some neurons encode the force and extent of movement. The nonprimary motor cortex, further divided into other areas such as the premotor and supplementary cortex, involves planning, initiating, and selecting the correct movement. Both hemispheres have a motor cortex, with each side controlling muscles on the opposite side of the body.
