The Spinal Cord and the Spinal Canal
Jean-Pierre Monnet, Yves Harmand in Pediatric Regional Anesthesia, 2019
The dorsal horns are well delineated. They reach posteriorly almost the dorsal limit of the spinal cord from which they are separated by a thin band of white matter, the marginal zone of Lissauer. The spinal cord is a cylindrical mass of nervous tissue that occupies the greatest part of the spinal canal, extending from the foramen magnum to end at the first to third lumbar vertebra. The spinal cord is covered with three membranes, or meninges, which contain a liquid, the cerebrospinal fluid. These meninges are pia mater, arachnoid and dura mater. The descending tracts of the spinal cord convey impulses for somatic movements, muscle tone, segmental reflexes, and visceral innervation. The spinal cord is a continuous unsegmented structure. The spinal cord presents several longitudinal furrows throughout its entire length. The ascending fibers of the spinal cord are organized into several fasciculi, mainly located in the funiculus posterior and the funiculus lateralis.
Infections of the Central Nervous System
Keith Struthers in Clinical Microbiology, 2017
The brain and spinal cord are protected by the skull and spinal column. Three connective tissue layers, the pia mater, arachnoid mater and dura mater, separate the nervous tissue from bone ( Figure 14.1 ). Between the first two layers in the subarachnoid space is the cerebrospinal fluid (CSF), which acts as a shock absorber. It is produced by the choroid plexus of the ventricles, exiting by the foramina of Luschka and Magendie, and then circulates around the brain and spinal cord. CSF is reabsorbed by the arachnoid granulations, which extend into the superior sagittal sinus, one of the great vessels draining the brain. The blood–CSF barrier consists of capillary endothelial cells resting on a basement membrane. The tight junction between these cells is such that constituents of the plasma, such as albumin, are unable to cross into the CSF under normal circumstances. The blood–brain barrier is the boundary between the vasculature and the brain tissue.
The Further Development of the Brain
John Gerhart, Marc Kirschner in Normal Table of Xenopus Laevis (Daudin), 2020
In the period of development, ranging from approximately stage 28 to approximately stage 40, the yolky material is consumed, the fibre tracts and later the commissures develop, and the segregation of the various brain structures continues. A chiasmatic ridge develops as a thickening of the floor of the forebrain at stage 29/30. It is rostrally separated from the thick lamina terminalis by a shallow groove. During this period of development the brain acquires more and more its general form and structure. The anlage is relatively large, semicircular in form and contains a large lumen in broad communication with the ventricle of the brain at stage 29/30. At stage 41 the anlage of the pia mater becomes visible at the level of the mesencephalon. At stage 42 the dura-endocranial membrane begins to differentiate also at the level of the mesencephalon. At stage 43 the dura-endocranial membrane, which develops further, becomes heavily pigmented dorsal to the brain.
Schizencephaly accompanied by occipital encephalocele and deletion of chromosome 22q13.32: a case report
Published in Fetal and Pediatric Pathology, 2019
Cihan Inan, N. Cenk Sayin, Hakan Gurkan, Engin Atli, Selen Gursoy Erzincan, Isil Uzun, Havva Sutcu, Sumeyra Dogan, Emine Ikbal Atli, Fusun Varol
Background: Schizencephaly is a neuronal migration anomaly characterized by presence of a cleft between ependymal layer of the ventricle and pia mater of the cerebral cortex. It may be associated with additional cerebral abnormalities, including polymicrogyria, pachygyria, gray matter heterotopy, ventriculomegaly and corpus callosum agenesis. Case Report: We present a female fetus with schizencephaly accompanied by occipital encephalocele, polymicrogyria, agenesis of the corpus callosum, dysmorphic facies and cardiac muscular ventricular septal defect. Array comparative genomic hybridization (array-cGH) analysis revealed a deletion of chromosome 22q13.32 including FAM19A5 gene that is a member of TAFA family. Conclusions: Schizencephaly may be accompanied by unexpected structural and genetic anomalies as in our case with occipital encephalocele, dysmorphic facies, cardiac ventricular septal defect and chromosome 22q13.32 deletion.
From Pluripotent Stem Cells to Multifunctional Cordocytic Phenotypes in the Human Brain: An Ultrastructural Study
Published in Ultrastructural Pathology, 2012
Viorel Pais, Leon Danaila, Emil Pais
Light microscopy and transmission electron microscopy were used to investigate surgical cases in a variety of pathological conditions (thromboses, tumors, cerebrovascular malformations, Moyamoya disease) to identify and characterize different phenotypes belonging to a new interstitial cell recently described ultrastructurally in the brain and here named “cordocyte.” Also, this work is an attempt to identify and characterize precursor/stem cells for cordocytic lineage in the perivascular areas, within perivascular nerves and pia mater (now considered a cordocytic-vascular tissue). Unexpected relationships and functions emerge from observations concerning these phenotypes, almost ubiquitous, but not yet fully studied in the brain.
Stress analysis of the cervical spinal cord: Impact of the morphology of spinal cord segments on stress
Published in The Journal of Spinal Cord Medicine, 2016
Norihiro Nishida, Tsukasa Kanchiku, Yasuaki Imajo, Hidenori Suzuki, Yuichiro Yoshida, Yoshihiko Kato, Daisuke Nakashima, Toshihiko Taguchi
Objective: Although there are several classifications for cervical myelopathy, these do not take differences between spinal cord segments into account. Moreover, there has been no report of stress analyses for individual segments to date. Methods: By using the finite element method, we constructed 3-dimensional spinal cord models comprised of gray matter, white matter, and pia mater of the second to eighth cervical vertebrae (C2–C8). We placed compression components (disc and yellow ligament) at the front and back of these models, and applied compression to the posterior section covering 10%, 20%, 30%, or 40% of the anteroposterior diameter of each cervical spinal cord segment. Results: Our results revealed that, under compression applied to an area covering 10%, 20%, or 30% of the anteroposterior diameter of the cervical spinal cord segment, sites of increased stress varied depending on the morphology of each cervical spinal cord segment. Under 40% compression, stress was increased in the gray matter, lateral funiculus, and posterior funiculus of all spinal cord segments, and stress differences between the segments were smaller. Conclusion: These results indicate that, under moderate compression, sites of increased stress vary depending on the morphology of each spinal cord segment or the shape of compression components, and also that the variability of symptoms may depend on the direction of compression. However, under severe compression, the differences among the cervical spinal segments are smaller, which may facilitate diagnosis.