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In neuroanatomy, the primary somatosensory cortex is located in the postcentral gyrus of the brain's parietal lobe, and is part of the somatosensory system. It was initially defined from surface stimulation studies of Wilder Penfield , and parallel surface potential studies of Bard, Woolsey, and Marshall.
Although initially defined to be roughly the same as Brodmann areas 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 receives the bulk of the thalamocortical projections from the sensory input fields [citation needed].
The postcentral gyrus is in the parietal lobe and its cortex is the primary somatosensory cortex (Brodmann areas 3, 2 and 1) collectively referred to as S1. BA3 receives the densest projections from the thalamus. BA3a is involved with the sense of relative position of neighboring body parts and amount of effort being used during movement.
This cortex is typically represented as a sensory homunculus which orients the specific body parts and their respective locations upon the homunculus. Areas such as the appendages, digits, penis, [2] and face can draw their sensory locations upon the somatosensory cortex. The areas which are finely controlled (e.g., the digits) have larger ...
The term primary comes from the fact that these cortical areas are the first level in a hierarchy of sensory information processing in the brain. This should not be confused with the function of the primary motor cortex, which is the last site in the cortex for processing motor commands. [1]
It transmits this information to the somatosensory cortex of the postcentral gyrus in the parietal lobe of the brain. [ 1 ] [ 2 ] The pathway receives information from sensory receptors throughout the body, and carries this in the gracile fasciculus and the cuneate fasciculus , tracts that make up the white matter dorsal columns (also known as ...
The spinothalamic tract is a nerve tract in the anterolateral system in the spinal cord. [1] This tract is an ascending sensory pathway to the thalamus.From the ventral posterolateral nucleus in the thalamus, sensory information is relayed upward to the somatosensory cortex of the postcentral gyrus.
The sensory cortex can refer sometimes to the primary somatosensory cortex, or it can be used as a term for the primary and secondary cortices of the different senses (two cortices each, on left and right hemisphere): the visual cortex on the occipital lobes, the auditory cortex on the temporal lobes, the primary olfactory cortex on the uncus of the piriform region of the temporal lobes, the ...