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Introduction: Background Material
Published in Nassir H. Sabah, Neuromuscular Fundamentals, 2020
The CNS is physically protected by: A bony structure in the form of the skull and vertebral column.A system of enveloping membranes, referred to as meninges. In mammals, the meninges are: the dura mater (outermost membrane), the arachnoid mater, and the pia mater (innermost membrane).The cushioning effect of the cerebrospinal fluid (CSF) that surrounds the brain and spinal cord. The CSF fills the subarachnoid space between the arachnoid mater and the pia mater.
The Skull and Brain
Published in Melanie Franklyn, Peter Vee Sin Lee, Military Injury Biomechanics, 2017
Tom Gibson, Nicholas Shewchenko, Tom Whyte
Beneath the skull are the meninges consisting of three layers of connective tissue: the dura mater, the arachnoid mater and the pia mater. The outermost dura mater is adherent or close to the inner surface of the bone. Beneath the dura mater is the middle covering, the thin and fibrous arachnoid. The narrow subdural space separating the dura and arachnoid is filled with a small amount of lubricant, preventing adhesion between the two membranes. A number of bridging veins cross the subdural space, draining from the underlying brain to the dura mater and the superior sagittal sinus. The third and innermost meningeal layer is the very thin, delicate and capillary-rich pia mater. The pia is intimately attached to the brain and dips down into the sulci and fissures. The gap between the arachnoid and pia is relatively large compared to the subdural space and is filled with cerebrospinal fluid.
Head-Brain-Sas Biomechanics and TBI in Sports and Accidents
Published in Youlian Hong, Routledge Handbook of Ergonomics in Sport and Exercise, 2013
The SAS that includes CSF and the trabeculae has a complex structure. This is due to abundance of trabeculae, which are in the form of rods (fibres), thin transparent plates, and tree-shaped that is extended from the arachnoid (subdural) to the pia mater. The pia mater adheres to the surface of the brain and follows all the brain contours including the folds of the cerebral and cerebella cortices. This gives the subarachnoid space a highly irregular shape and makes the flow of CSF around the brain non-laminar and complicated. This interaction between the CSF and the trabeculae suggests that their functions are not independent. The interaction between the fluid and solid phase mechanically support the brain.
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.