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The dark portion of the brain
Last reviewed: 20.11.2021
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Behind the central sulcus is the parietal lobe (lobus parietalis). The posterior border of this lobe is the parieto-occipital furrow (sulcus parietooccipitalis). This furrow is located on the medial surface of the cerebral hemisphere, deeply dissecting the upper edge of the hemisphere and passes to its upper-lateral surface. The boundary between the parietal and occipital lobes on the dorsolateral surface of the cerebral hemisphere is the conventional line - continuation of the parieto-occipital furrow downwards. The lower boundary of the parietal lobe is the lateral sulcus (its posterior branch) separating this part (its anterior sections) from the temporal lobe.
Within the parietal lobe, a postcentral furrow is identified (sulcus postcentralis). It starts from the lateral furrow at the bottom and ends at the top, not reaching the upper edge of the hemisphere. The postcentral furrow lies behind the central furrow almost parallel to it. Between the central and postcentral grooves is the postcentral gyrus (gyrus postcenralis). At the top, it passes to the medial surface of the cerebral hemisphere, where it joins the precentral gyrus of the frontal lobe, forming with it a paracentral lobulus paracentralis. On the upper lateral surface of the hemisphere, below, the postcentral gyrus also passes into the precentral gyrus, embracing the central furrow from below. From the postcentral groove an intralumenal furrow (sulcus intraparietalis) extends posteriorly. It is parallel to the upper edge of the hemisphere. Above the intra-temporal furrow there is a group of small convolutions, called the upper parietal lobes (lobulus parietalis superior). Below this groove lies the inferior parietal lobe (lobulus parietalis inferior), within which two convolutions are distinguished: the marginal (gyrus supramarginalis) and the angular (gyrus angularis). The marginal gyrus covers the end of the lateral sulcus, and the angular gashrove - the end of the upper temporal sulcus. The lower part of the lower parietal lobule and the lower parts of the postcentral gyrus adjacent to it, together with the lower part of the precentral gyrus, overhanging the islet part, form the frontal-parietal covering of the islet (operculum frontoparietale).
The dark lobe includes the posterior central gyrus (primary sensory or projection sensory cortical area) and the associative parietal cortex. Located between the tactile and visual cortex, the parietal lobe is important in the perception of three-dimensional space. In the upper parietal lobule, sensory flows from the primary somatosensory cortex are integrated with the effects of higher mental functions (attention, motivation, etc.), especially during arbitrary purposeful limb movements.
The lower parietal lobe, consisting of the anterior part (gyrus supramarginalis) and the posterior (gyrus angularis), has even more complex functions. Here, multimodal sensory information (somatic sensations, sight and hearing) is integrated with the processes of perception of internal and external space, language and symbolic thinking, directed attention to external objects and to one's own body.