- Postcentral gyrus
Infobox Brain
Name = Postcentral gyrus
Latin = gyrus postcentralis
GraySubject = 189
GrayPage = 823
Caption = Postcentral gyrus of the human brain.
Caption2 = Brodmann areas 3, 1 and 2 of human brain. Brodmann area 3 is in red, area 1 in green, and area 2 in yellow.
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BrainInfoType = hier
BrainInfoNumber = 87
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DorlandsPre = g_13
DorlandsSuf = 12405446
The lateral postcentral gyrus is a prominent structure in theparietal lobe of the humanbrain and an important landmark. It was initially defined from surface stimulation studies of Penfield, and parallel surface potential studies of Bard, Woolsey, and Marshall. Although initially defined to be roughly the same asBrodmann area s 3, 1 and 2, more recent work by Kaas has suggested that for homogeny with other sensory fields only area 3 should be referred to as "primary somatosensory cortex", as it received the bulk of the thalamocortical projection from the sensory input fields.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 ahomunculus 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 below.Brodmann areas 3, 1 and 2
Brodmann areas 3, 1 and 2 comprise the primary
somatosensory cortex of the humanbrain . Because Brodmann sliced thebrain somewhat obliquely, he encountered area 1 first; however, fromrostral tocaudal the Brodmann designations are 3, 1 and 2, respectively.This area of cortex, as shown by
Wilder Penfield and others, has the pattern of ahomunculus . 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 ofneuron s in thecerebral cortex are devoted to processing information from these areas.These areas contain cells that project to the
secondary somatosensory cortex .Clinical significance
Lesions affecting the primary somatosensory cortex produce characteristic symptoms including:
agraphesthesia ,astereognosia , loss ofvibration ,proprioception andfine touch (because the third-order neuron of the medial-lemniscal pathway cannot synapse in the cortex). It can also producehemineglect , if it affects the non-dominant hemisphere.It could also reduce
nociception ,thermoception andcrude touch , but since information from thespinothalamic tract is interpreted mainly by other areas of the brain (seeinsular cortex andcingulate gyrus ), it is not as relevant as the other symptoms.ee also
*
Brodmann area
*List of regions in the human brain
=AdditionalExternal links
* - area 1
* - area 2
* - area 3
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