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The Skull and Brain
Published in Melanie Franklyn, Peter Vee Sin Lee, Military Injury Biomechanics, 2017
Tom Gibson, Nicholas Shewchenko, Tom Whyte
The main parts of the brain are the cerebrum, cerebellum and brainstem. The cerebrum is the most superior part of the brain and is composed of two hemispheres accounting for 83% of the total brain mass. The surfaces of the cerebral hemispheres have ridges and furrows called gyri and sulci, respectively. A number of deeper chasms in the brain tissue are referred to as fissures, which divide the brain into lobes and separate the hemispheres. The only attachment between the hemispheres is a fibrous bundle called the corpus callosum. The cerebellum is the second largest part of the brain, accounting for around 11% of the total brain mass. It is located underneath the occipital lobes in the posterior cranial fossa of the skull. The brainstem is located at the base of the skull where the spinal cord enters the cranial cavity (Figure 8.4).
Introduction
Published in Andrea Varsavsky, Iven Mareels, Mark Cook, Epileptic Seizures and the EEG, 2016
Andrea Varsavsky, Iven Mareels, Mark Cook
The general structure of these networks is illustrated in Figure 1.3(b) and (c). All mammalian brains look roughly like this, although the details vary. For example neurons in the cerebral cortex of humans are much more densely inter-connected than in animals, and is believed to be one reason for the more sophisticated capabilities of humans. The gray matter in this figure is the cortex, folded to form gyri and sulci and containing all the cortical neurons. Between cortex and subcortex is the white matter — a region composed mostly of connections made between different areas of the brain. The majority of these connections are between different cortical regions, but subcortical systems such as the thalamus also communicate with the cortex through the white matter. Very few neurons can be found in this region.
Central nervous system
Published in A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha, Clark’s Procedures in Diagnostic Imaging: A System-Based Approach, 2020
A Stewart Whitley, Jan Dodgeon, Angela Meadows, Jane Cullingworth, Ken Holmes, Marcus Jackson, Graham Hoadley, Randeep Kumar Kulshrestha
The surface layer or cortex is composed of nerve cells (grey matter). In order to accommodate as large an area as possible, it is folded and has a wrinkled appearance, with gyri and sulci. The most important of these are the central sulcus (fissure of Rolando) that separates the frontal and parietal lobes; the lateral sulcus (fissure of Sylvius) that separates the temporal lobe from the frontal and parietal lobes; and the pre- and post-central gyri that lie in front of and behind the central sulcus, respectively (Fig. 11.1c).
A mesoscale finite element modeling approach for understanding brain morphology and material heterogeneity effects in chronic traumatic encephalopathy
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2021
A. Bakhtiarydavijani, G. Khalid, M. A. Murphy, K. L. Johnson, L. E. Peterson, M. Jones, M. F. Horstemeyer, A. C. Dobbins, R. K. Prabhu
The human brain is both heterogeneous (white/gray matter, fractal vasculature) and anisotropic (e.g. radial cortical organization, oriented fiber tracts). Gray matter is located on the outer surface of the brain and contains numerous cell bodies and neuronal somas. The gray matter surrounds the white matter that mostly consists of myelinated axon tracts. In addition, to accommodate the large cortical sheet in a limited volume, the neocortical gray matter is more folded in large-brained animals (Allman 2000). The gyri and sulci are the convex and concave folds of the cerebral cortex, respectively. The gyri often about the inside surface of the cranium, except in major fissures or involutions such as the insula. The major cortical features (e.g. the Sylvian fissure and central sulcus) are readily identifiable with some detailed variation in the folding from person to person. Recent efforts into the development of these convolutions (initiating after the 23rd week of gestation) generate stress fields in the brain (Raghavan et al. 1997; Bayly et al. 2013; Budday et al. 2014; Goriely et al. 2015). These stress fields may be released with time considering the viscoelastic behavior of brain tissue. The extent of brain convolutions also vary due to malformations such as lissencephaly and polymicrogyria that enhance or reduce folding on the brain surface (Allman 2000). Furthermore, the brain is encased in a multilayered, fibrous structure that includes the pia, arachnoid, and dura mater, of which the pia mater is on the surface of the brain and follows its folds. An understanding of these features is then required to decide what features to include in a head model that can be achieved using computational approaches.
A Functional BCI Model by the P2731 working group: Physiology
Published in Brain-Computer Interfaces, 2021
Ali Hossaini, Davide Valeriani, Chang S. Nam, Raffaele Ferrante, Mufti Mahmud
Functional subdivisions of a cerebral lobe can often be identified with the gyri and sulci that compose it. Table 2 offers a sample of the functional regions often targeted by BCI sensors.