Locations of the primary cortex and related motor areas

The primary motor cortex (the motor cortex):

• Is the main part of the cerebral cortex concerned with initiating voluntary muscle action.
• Contains upper motor neurons whose axons pass either to the spinal cord for excitation of lower motor neurons in the ventral horns (corticospinal tracts) or to brainstem cranial nerve motor nuclei for similar activation of their lower motor neurons (with axons in the cranial motor nerves).
• Is located just anterior to the central sulcus in the frontal lobe of the cerebral cortex (the pre-central gyrus).
• Different parts of the motor cortex are related to muscles of different parts of the body, with the face, pharynx and larynx most ventro-lateral and the lower parts of the body in the most medial regions (in the midline). (see: motor homunculus).
• In addition to this primary motor cortex, there are a number of more specialised areas related to motor activity. These include:


• • premotor cortex
• • supplementary motor cortex
• • frontal eye fields
• • Broca's speech motor area