Primary somatosensory cortex

The lateral postcentral gyrus is a prominent structure in the parietal lobe of the human brain and an important landmark. It is almost the same as Brodmann areas 3, 1 and 2.

Postcentral gyrus
The lateral postcentral gyrus is bounded by:
 * medial longitudinal fissure medially (to the middle)
 * central sulcus rostrally (in front)
 * postcentral sulcus caudally (in back)
 * lateral sulcus inferiorly (underneath)

It is the location of primary somatosensory cortex, the main sensory receptive area for the sense of touch. Like other sensory areas, there is a map of sensory space called a homunculus in this location. For the primary somatosensory cortex, this is called the sensory homunculus. See a somewhat fanciful and highly schematic representation of the sensory homunculus at lower right.

Brodmann areas 3, 1 and 2
Brodmann areas 3, 1 and 2 comprise the primary somatosensory cortex of the human brain. Because Brodmann sliced the brain somewhat obliquely, he encountered area 1 first; however, from rostral to caudal the Brodmann designations are 3, 1 and 2, respectively. This area of cortex, as shown by Wilder Penfield and others, has the pattern of a homunculus. That is, the legs and trunk fold over the midline; the arms and hands are along the middle of the area shown here; and the face is near the bottom of the figure. While it is not well-shown here, the lips and hands are enlarged on a proper homunculus, since a large number of neurons in the cerebral cortex are devoted to processing information from these areas.

These areas contain cells that project to the secondary somatosensory cortex.