Somatotopic map of major body areas in primary motor cortex. Within the broad areas, no one area exclusively controls the movement of a single
body region, and there is much overlap and duplication of cortical representation. Relative sizes of body structures are proportional to the number
of neurons dedicated to their motor control. Only the right motor cortex, which principally controls muscles on the left side of the body, is shown.
Primary motor cortex
(a) The major motor areas of cerebral cortex. (b) Midline view of the right side of the brain showing the supplementary motor cortex, which
lies in the part of the cerebral cortex that is folded down between the two cerebral hemispheres. Other cortical motor areas also extend onto
this area. The premotor, supplementary motor, primary motor, somatosensory, and parietal-lobe association cortexes together make up the