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Nervous system
Published in David Sturgeon, Introduction to Anatomy and Physiology for Healthcare Students, 2018
The brain and spinal cord (CNS) are surrounded by three protective membranes collectively known as meninges. The outermost of these is called the dura mater from the Latin for ‘tough mother’. It is a strongest and thickest of the three membranes and is divided into outer and inner layers (Figure 12.11). The outer layer is attached to the periosteum of the cranium (Chapter 4) whilst the inner layer has multiple folds that mirror the outline of the brain beneath. For the most part, the two layers are fused together to provide support and stabilisation for the brain. However, in some areas, they separate to accommodate a number of dural venous sinuses that drain cerebrospinal fluid (CSF) and venous blood from the brain, and return it to the internal jugular veins of the neck. The middle meninx (singular of meninges) is the arachnoid mater from the Greek for ‘spider-like’. It is separated from the dura mater by the subdural cavity which is lubricated by a thin film of fluid. Finger-like projections called arachnoid villi project upwards from the arachnoid mater into the largest of the dural venous sinuses (the superior sagittal sinus) in order to absorb CSF mentioned above. Directly beneath the arachnoid mater is the subarachnoid space which is filled with CSF. The arachnoid mater derives its name (‘spider-like mother’) from the thousands of web-like extensions that span this space and anchor it to the third and innermost meninx, the pia mater.
Benzene Hematotoxicity
Published in Muzaffer Aksoy, Benzene Carcinogenicity, 2017
"There were scattered hyperemic or hemorrhagic spots in the dermal region of the head. There was hyperemia in the meninx, and brain was oedematous. There were small bleedings in meninx.24 In thorax both lungs were oedematous and there were diffuse pinpoint bleedings. The organs of the abdomen were hyperemic. The mucous membranes and serosa were also hyperemic. The blood obtained in autopsy was analyzed and found to contain alcohol 20 mg/100 ml (normal: 30 mg/100 ml). There was no carbon monoxide. The pieces of abdominal organs did not exhibit narcotics and other toxic materials. The liquid material which was used as thinner in the workplace contained 94% benzene."
ENTRIES A–Z
Published in Philip Winn, Dictionary of Biological Psychology, 2003
The meninges are layers of connective tissue that surround the BRAIN and SPINAL CORD; the singular noun is meninx. Around the brain are three layers: the DURA MATER (Latin, hard mother) is a relatively thick, tough but flexible layer of connective tissue that surrounds the brain and other meningeal layers. The outer surface of the dura adheres to the inner surface of the SKULL. Beneath the dura is the SUBDURAL SPACE, through which blood vessels pass, and below is the ARACHNOID MEMBRANE (from Greek, arachne: spider—the arachnoid membrane is like a spider's web). The arachnoid is thinner and softer than the dura. It gives rise to the ARACHNOID TRABECULAE (Latin, trabecula: a little beam) which descend through the SUBARACHNOID SPACE to contact the PIA MATER (Latin, pious mother) a meningeal layer thinner still than the arachnoid, which contains small blood capillaries and is attached directly to the surface of the brain, following faithfully the GYRI AND SULCI. All three meningeal layers cover the brain and spinal cord but the arachnoid is not present around the SPINAL NERVES and CRANIAL NERVES, which are covered by a lining that is in effect a fusion of the dura and pia mater. The spaces between the meningeal membranes is filled with CEREBROSPINAL FLUID (CSF), which gains access to the subarachnoid space from the cerebral VENTRICLES (where it is synthesized) via three openings from the fourth ventricle: the FORAMINA OF LUSHKA (one in each hemisphere) and the FORAMEN OF MAGENDIE. The function of the meninges is effectively to suspend the brain in fluid, supporting it and absorbing shocks. The fact that it is suspended in fluid effectively decreases the weight of the brain. Moreover, the fact that it is supported in a triple layer of membranes, lubricated by fluid, means that shearing forces generated following sudden impact can be absorbed. Were it not for this, sudden blows to the head would cause tissue to shear—to tear and fragment.
Complex spinal dysraphism: myelomenigocele associated with dorsal bony spur, split cord malformation type I, syringomyelia, lipoma and tethered cord
Published in British Journal of Neurosurgery, 2023
Gautam Dutta, Ankit Shah, Manish Garg, Robin Gupta, Ghanshyam Singhal, Daljit Singh, Anita Jagetia, Hukum Singh, Arvind Srivastava, Ravindra Saran
The term ‘diastematomyelia’ was first used by Ollivier in 1837 to describe an abnormality of the spinal cord in which the dura is separated by a bony spike or a rigid fibrous band.1 Pang et al.2 and Pang3 had tried to shed light regarding the classification of double cord malformations and proposed a unified theory to explain the embryogenetic mechanisms of all variants of SCMs. This theory is founded on the presence of anomalous neuroenteric canal and maintains that the endomesenchymal tract causes all double cord malformations. They classified SCMs as type I, where the hemicords are always invested with individual dural sacs and the medial walls of the sacs always ensheathe a rigid (bony or cartilaginous) midline spur. Here, the cells of the meninx primitive pass in between the split cord and migrate dorsally and the sclerogenic potential of these cells leads to the formation of the midline bony spur and the hypertrophied posterior arch. In type II, the hemicords are always within a single dural sac and the mesenchymal cells that lie between the hemicords do not tap the sclerogenic cells of the meninx primitiva, hence only a fibrous septum is formed instead of a bony spur.
Summarizing the medieval anatomy of the head and brain in a single image: Magnus Hundt (1501) and Johann Dryander (1537) as transitional pre-Vesalian anatomists
Published in Journal of the History of the Neurosciences, 2022
Dryander included the same orienting terms within the illustration frame as Hundt did (vide supra), and the same figure elements, but the labeling and the legend were redone. “Vertex” is written on the frame itself (top center), but also redundantly indicated by the symbol A: In suprema parte cranij verticem capitis designat (Indicates the vertex of the head in the uppermost part of the cranium). Whereas Hundt had used a stratigraphic approach, in which progressively deeper tissue layers were portrayed as lower on the diagram (even if the different layers were visually indistinguishable in the diagram), Dryander portrayed the superficial layers (above the cranium) as separate flaps to each side: AB. In utroq[ue] latere dependentem curiculam primam capitis, cui capilli innituntur (the first skin of the head, hanging down on both sides, in which the hair is fixed); C. Internam partem primae cuticulae exprimit (the inner side of the first skin); D. Pericranium, hoc est, mox contingens, exterius os cranij cuticula est (pericranium, the outer skin immediately touching the bone of the cranium); F. Dura menynx intra cranium (the hard meninx within the skull; i.e., dura mater); G. Pia mater est, mollior atq[ue] te nuis cuticula proxime cerebrum obuelans (pia mater, the thin softer skin immediately touching the bone of the cranium; i.e., the pericranium).
Cerebrospinal fluid leaks secondary to dural tears: a review of etiology, clinical evaluation, and management
Published in International Journal of Neuroscience, 2021
Jason Gandhi, Andrew DiMatteo, Gunjan Joshi, Noel L. Smith, Sardar Ali Khan
The meninges are composed of three membrane structures that encapsulate the brain and spinal cord. The three membranes of the meninges from most superficial to deep are respectively the: dura, arachnoid, and pia mater. The dura mater is also referred to as the pachymeninx or “thick meninx”, while the pia and arachnoid mater collectively are referred to as the leptomeninx or “thin meninx” [5]. The dura itself is composed of three layers: the most superficial layer called the endosteal (i.e. periosteal), the meningeal layer, and the deepest layer called the dural border cell layer [6,7]. The dural border cell layer interacts with the arachnoid barrier cell layer and basement membrane of the arachnoid mater. It is in the arachnoid reticular layer and subarachnoid space that the CSF is contained. The depth of the subarachnoid space is variable depending on the relationship between the arachnoid and pia mater [7].