Library · Anatomy
Parietal lobe
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The cerebral cortex, the layer of gray matter that wraps around the brain, is divided into lobes, and the parietal is one of them. Inside it lie the primary and secondary somatosensory cortices, the areas where everything the body feels arrives and is interpreted: touch, temperature, pain, the position of the joints.
The primary one has a name of its own: the postcentral gyrus. A gyrus is a fold of cortex, and this one sits just behind the central sulcus, the groove that separates the frontal lobe from the parietal. What reaches it comes from the thalamus, the brain's relay station, and specifically from its ventral posterolateral nucleus.
The interesting part is how it is organized. Each region of the body is assigned its own strip of the postcentral gyrus, and always the strip on the opposite side: the left hand arrives on the right. That correspondence is called somatotopy, and it builds the map known as the sensory homunculus. The whole body is drawn across that strip of cortex, part by part.
In brief
The parietal lobe is one of the lobes into which the cerebral cortex is divided, and it houses the primary and secondary somatosensory cortex.
The primary somatosensory cortex, or postcentral gyrus, sits just behind the central sulcus and receives sensory information from the ventral posterolateral nucleus of the thalamus.
Each region of the body maps to its own zone of the postcentral gyrus on the opposite side; this somatotopy builds the sensory homunculus.
The whole body is drawn across that strip of cortex, part by part.
Sources (2)
- National Center for Biotechnology Information, StatPearls PublishingNeuroanatomy, Cerebral Cortex, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingNeuroanatomy, Somatosensory Cortex, StatPearlsPublished
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