At the primary motor cortex, motor representation is orderly arranged ( in an inverted fashion ) from the toe ( at the top of the cerebral hemisphere ) to mouth ( at the bottom ) along a fold in the cortex called the central sulcus.
22.
Note that the central sulcus ( sometimes referred to as the central fissure ) divides the primary motor cortex ( on the precentral gyrus of the posterior frontal lobe ) from the somatosensory cortex ( on the postcentral gyrus of the anterior parietal lobe ).
23.
Where BA 1 occupies the apex of the postcentral gyrus, the rostral border of BA 3a is in the nadir of the Central sulcus, and is caudally followed by BA 3b, then BA 1, with BA 2 following and ending in the nadir of the postcentral sulcus.
