Interlobar sulci

Interlobar sulci or grooves, serve to delineate and distinguish the major cerebral lobes, effectively segregating them from one another. A significant sulcus, called the central sulcus, resides roughly in the middle of the lateral surface of the cerebral hemisphere. It descends and moves forward from the upper edge of the hemisphere, located near the longitudinal cerebral fissure, just slightly behind its midpoint. The central sulcus acts as a boundary separating the frontal lobe located at the front from the parietal lobe positioned at the rear.

Another interlobar sulcus is the lateral sulcus, which originates at the base of the brain and extends laterally between the frontal and temporal lobes. Once it reaches the lateral surface of the cerebral hemisphere, it continues in a posterior and upward direction, forming a dividing line between the parietal and temporal lobes. Finally, it culminates by becoming encompassed by the supramarginal gyrus.

The parieto-occipital sulcus is an additional important interlobar sulcus predominantly visible on the medial side of the brain. Here it separates the occipital lobe at the back from the pre-cuneus region of the parietal lobe in the front. On the superolateral surface of the brain, there is an imaginary line connecting this indentation of the parieto-occipital sulcus to the pre-occipital notch along the inferior border. The area behind this line constitutes the occipital lobe.

The limbic lobe, a functional lobe of the cortex, consists of the cingulate gyrus and the parahippocampal gyrus. As it extends around the corpus callosum and reaches the medial part of the temporal lobe as the parahippocampal gyrus, several interlobar sulci separate it from the rest of the cortex. For instance, the callosal sulcus serves as a boundary between the cingulate gyrus and the underlying corpus callosum, while superiorly, the cingulate sulcus separates it from the medial frontal gyrus, paracentral lobule, and the precuneus. Inferiorly, the collateral and rhinal sulci create a division between the parahippocampal gyrus and uncus from the laterally situated occipitotemporal gyrus.

In essence, interlobar sulci fulfill a critical role in demarcating the boundaries of cerebral lobes, enabling the separation and organization of distinct brain regions.