One gyrus may be continuous in another surface of the hemisphere: the inferior temporal gyrus (both lateral and basal surface of the temporal lobe) with the parahippocampal gyrus (both medial and basal surface of the temporal lobe). Often, we consider a gyrus as areas of the brain consisting of several gyri, as in the case of the paracentral and medial frontal gyri. 4 , 5Because most of the sulci are interrupted, the anatomical boundaries of the gyri are not always clearly demarcated. The central sulcus and the calcarine sulcus are uninterrupted in 92% of the cases. 3 , 4 , 5Only four sulci are consistently uninterrupted: the Sylvian fissure, the collateral sulcus, the callosal sulcus, and the parieto-occipital sulcus. We review the anatomy of the cortical arteries as they relate to the sulci and gyri.Īlthough there is great variation in the anatomy of the sulci and gyri among individuals, there is a common pattern in the organization of the sulci and gyri of the cerebrum that can be recognized and studied. We discuss the anatomy of the opercula and the insula as we review the anatomy of the Sylvian fissure. We follow Yasargil’s division, since this separates the central lobe in a distinct lobe, highlighting its importance as the primary sensory–motor area. Yasargil’s division was a surgical conception of the cerebrum, taking in consideration function and the embryological aspects of cortical organization. Yasargil 4proposed a division into seven cerebral lobes: frontal, central (precentral, postcentral, and paracentral gyri), parietal, occipital, temporal, insular, and limbic. The cerebrum is commonly divided into five lobes: frontal, temporal, parietal, occipital, and insula. Third, there is a relationship between brain structure and brain function that allows the surgeon to plan in advance which intraoperative monitoring may be necessary for specific brain regions. 4Examples are tumors extending in the limbic lobe and tumors commonly spreading from the opercula to the insula. 2Second, tumor location and extensions are often correlated with the anatomy of the gyri, as tumors are often located in a specific gyrus or lobe, and tumors are known to extend depending on the cytoarchitecture of the area where they originated. 2 , 3 , 4 , 5First, understanding the relation of the tumors with the sulci and gyri is helpful in planning the craniotomy for tumor resection. However, knowledge of the anatomy of the sulci and gyri of the brain provides the surgeon with several key elements to plan procedures. 1Localization of function cannot depend only on anatomical landmarks. The localization of function and certain anatomical cortical regions, such as Broca area, is variable among individuals and the surgeon depends upon cortical stimulation and cortical mapping to correlate function and anatomy with certainty. Although the whole cortex may be regarded as eloquent if we consider function, we use the term eloquent to distinguish specific areas of the brain that carry a higher risk of morbidity and disability in the postoperative period. Eloquent cortical area will depend also on whether the area is in the dominant hemisphere, as in the case of speech areas. These areas commonly include the precentral gyrus (primary motor cortex), postcentral gyrus (primary sensory cortex), supplementary motor area (speech and motor function), perisylvian area (language), medial occipital lobe (primary visual cortex), and medial temporal lobe (memory). We review the anatomy of the sulci and gyri of the cerebrum and divide it into seven lobes: frontal, central (precentral, postcentral, and paracentral gyri), parietal, occipital, temporal, insular, and limbic.Įloquent cortical areas are areas of the cortex that if removed may result in loss of linguistic ability, motor function, or sensory perception. However, knowledge of the anatomy of the sulci and gyri of the brain is helpful in planning stimulation, tumor resection, understanding tumor extensions, and correlating the findings of the magnetic resonance imaging with the operative field. The localization of function in certain anatomical cortical regions, such as Broca area, is variable among individuals and the surgeon depends upon cortical stimulation and cortical mapping to correlate function and anatomy with certainty. These areas commonly include the precentral gyrus (primary motor cortex), postcentral gyrus (primary sensory cortex), supplementary motor area (speech and motor function), the perisylvian area (language), medial occipital lobe (primary visual cortex), and medial temporal lobe (memory). Eloquent cortical areas are areas of the cortex that if removed may result in loss of linguistic ability, motor function, or sensory perception. We review the anatomy of eloquent cortical brain regions. 2 Anatomy of Eloquent Cortical Brain Regions Antonio Cesar de Melo Mussi and Evandro de Oliveira
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