DOCSLIB.ORG

40505-Functional Anatomy of the Spinal Cord

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
40505-Functional Anatomy of the Spinal Cord European Course in Neuroradiology Module 1 - Anatomy and Embryology Dubrovnik, October 2018 Overview Spinal Anatomy Spaces & Meninges Spinal Cord • spinal meninges & spaces Johan Van Goethem • spinal cord Anatomy of the spinal Anatomy of the spinal meninges meninges • three layers (outer to inner) • dura mater (also known as theca or pachymeninx) • arachnoid mater • pia mater • collectively the arachnoid and pia mater together are known as the leptomeninges • there are two actual spaces: epidural and subarachnoid Anatomy of the dura Anatomy of the arachnoid • stratum periostale • stratum meningeale: • separated from the dura • extension of the dura mater from by a thin film of lymph the posterior cranial fossa • lies free apart from attachments to • thin avascular membrane the tectorial membrane and lining the dural sac and posterior longitudinal ligament on the body of the axis nerve root sheaths • stabilised by anterior and posterior spinal nerve roots, which pierce it segmentally • a posterior median septum lies over the spinal cord, formed by web-like arachnoid processes • in between: a layer of fat containing the internal vertebral venous plexus Anatomy of the pia Epidural space • space between the dura mater and the periosteum and • invests the spinal cord and ligaments of the vertebral canal the spinal nerve roots, • blending in with the superiorly bounded by the fusion of the dura with the foramen magnum epineurium • content • continuous with the ligamentum denticulatum, • fat which at its lateral border has a series of • internal vertebral venous plexus triangular processes that are fixed to the dura mater • spinal nerve roots below S2 Subarachnoid space • thin cell layer between the closely apposed arachnoid and pia mater • content: • arachnoid trabeculae • CSF • veins • arteries: radicular, segmental, medullary and spinal Cranium Space Typical? Example traumatic Epidural Potential No hematoma (arterial) traumatic Subdural Potential Yes hematoma (bridging veins) haemorrhage Subarachnoid Actual Yes (aneurysm, CAA), infection Cranium Spine Myelography Space Typical? Example Space Typical? Example • occasional direct puncture of epidural or hematoma, subdural space traumatic Epidural Potential No Actual Yes infection, neoplasia, hematoma (arterial) disc herniation • leakage after subarachnoid puncture traumatic Subdural Potential Yes hematoma Potential No - (bridging veins) • 35% in epidural space haemorrhage continuous w/ Subarachnoid Actual Yes (aneurysm, CAA), Actual Yes • 2% in subdural space cranium infection Myelography Myelography Milants et al. European Journal of Radiology 1993 Milants et al. European Journal of Radiology 1993 Epidural space Spinal Cord • vertebral canal • conus medullaris: adult Th12- L1 • filum terminale • cauda equina • gray matter: anterior and posterior horns • white matter: anterior, lateral and posterior tracts Spinal nerves • ventral and dorsal roots • intervertebral foramen • each pair (31) innervates a body segment: dermatomes • cervical (8 p.), thoracic (12 p.), lumbar (5 p.), sacral (5 p.) and coccygeal (1 p.) 40-year-old woman So what is this? • gradual and uniform onset of • Lichtheim's disease • diminished pressure, vibration and touch sense • Lou Gehrig's disease • tingling and numbness of legs, arms and trunk that progressively worsens • Lyme disease • pain and temperature sense are normal • Devic’s disease • motor function is preserved, but slight ataxia And the answer is ... Let’s go back ... • gradual and uniform onset of • Lichtheim's disease • diminished pressure, vibration and touch sense • Lou Gehrig's disease • tingling and numbness of legs, arms and trunk that progressively worsens • Lyme disease • pain and temperature sense are normal • Devic’s disease • motor function is preserved, but slight ataxia Some anatomy Spinothalamic tract • anterior • coarse touch and pressure • lateral • pain • temperature Source: Prometheus • itch Anatomical atlas • 3 ascending pathways • sexual • 2 descending pathways Source: Prometheus Anatomical atlas Spinocerebellar tract Fasciculus gracilis & cuneatus • posterior or dorsal columns • unconscious • tracts of Goll and proprioception Burdach • walking • running • conscious proprioception • biking • fine touch, fine • ... pressure and vibration • 2-point discrimination Source: Prometheus Source: Prometheus Anatomical atlas Anatomical atlas Fasciculus gracilis & cuneatus Fasciculus gracilis & cuneatus Source: Prometheus Source: Prometheus Anatomical atlas Anatomical atlas Fasciculus gracilis & cuneatus Subacute combined degeneration • degeneration of the posterior (and lateral) columns as a result of vitamin B12 deficiency • dietary deficiency of B12, malabsorption of B12 in the terminal ileum, lack of intrinsic factor So what is this? 52-year-old woman • unable to move her legs after abdominal procedure •• Lichtheim'ssubacute combined disease degeneration • areflexic in the lower extremities with negative •• Louamyotrophic Gehrig's diseaselateral sclerosis Babinski testing bilaterally •• Lymeneuroborreliosis disease •• Devic’sneuromyelitis disease optica • sensory level to pain and temperature extended up to Th10 • other intact Corticospinal tract Extrapyramidal tracts • unconscious motor • automated • lateral • lateral • rubrospinalis • conscious motor • arm and hands fine • anterior motor • 20% • medial • reticulospinalis anterior, • cervical tectospinalis, vestibulospinalis Source: Prometheus Source: Prometheus • legs and trunk Anatomical atlas Anatomical atlas Back to our case Back to our case • lesions of pyramid tracts or extrapyramid tracts are always combined due to their close proximity • lesions of these tracts may cause Babinski sign • no reflex = no α-motorneuron function Source: Prometheus Source: Prometheus Anatomical atlas Anatomical atlas Back to our case Spinal cord infarction Source: Prometheus Anatomical atlas 9-year-old girl Anatomy revisited • acute flaccid paresis • AFP is the most common sign of acute polio, and used for surveillance during polio outbreaks Source: Wikipedia What is all the other stuff? What is all the other stuff? • interneuron coordination (reflexes, proprioception) Source: Prometheus Anatomical atlas • autonomic nervous system • mostly diffuse Conclusion • spinal meninges & spaces • spinal cord anatomy revisited.
Load more

Recommended publications
  • Why Do Bridging Veins Rupture Into the Virtual Subdural Space?
    J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.47.2.121 on 1 February 1984. Downloaded from Journal of Neurology, Neurosurgery, and Psychiatry 1984;47:121-127 Why do bridging veins rupture into the virtual subdural space? T YAMASHIMA, RL FRIEDE From the Department ofNeuropathology, University of Gottingen, Gottingen, Federal Republic of Germany SUMMARY Electron microscopic data on human bridging veins show thin walls of variable thick- ness, circumferential arrangement of collagen fibres and a lack of outer reinforcement by arach- noid trabecules, all contributory to the subdural portion of the vein being more fragile than its subarachnoid portion. These features explain the laceration of veins and the subdural location of resultant haematomas. Most subdural haematomas due to venous bleeding walls are delicate, lacking muscle fibres, with only a have been attributed to lacerations in bridging veins. thin fibrous wall and a thin elastic lamina adjacent to These veins form short trunks passing directly from the endothelial layer. The conclusions of these two the brain to the dura mater, almost at right angles to authors, have gained wide acceptance, although guest. Protected by copyright. both. Between these two points, bridging veins take there was little evidence concerning the fragility of a straight course with no tortuosity to allow for the the vein walls. possible displacement of brain.' Trotter2 speculated The purpose of the present communication is to that subdural haematomas are invariably due to provide electron microscopic data on tissue fixed in trauma tearing large veins, an interpretation situ, which might throw some light on to the lacera- elaborated by Krauland.3 According to Leary,4 the tion mechanism of bridging veins and its relationship common sources of subdural haematomas are rup- to the development of subdural haematoma.
    [Show full text]
  • Intramedullary Cystic Lesions Ofthe Conus Medullaris
    J Neurol Neurosurg Psychiatry: first published as 10.1136/jnnp.31.2.106 on 1 April 1968. Downloaded from J. Neurol. Neurosurg. Psychiat., 1968, 31, 106-109 Intramedullary cystic lesions of the conus medullaris SAMI I. NASSAR, JAMES W. CORRELL, AND EDGAR M. HOUSEPIAN From the Department of Neurosurgery, College ofPhysicians and Surgeons, Columbia University, and the Neurological Institute of the Columbia-Presbyterian Medical Center, New York, U.S.A. Intramedullary cystic lesions of the conus medullaris of the aetiology, these cysts may simulate the clinical are rare. Although an extensive literature describes picture of syringomyelia. syringomyelia as being a frequent basis for cystic The cases of cysts of the conus medullaris re- cervico-thoracic lesions it is apparent that this ported here simulated the clinical picture of does not occur frequently in the lumbosacral region syringomyelia, tumour, or lumbar disc disease. (Kirgis and Echols, 1949; Netsky, 1953; Rand and The radiographic findings in each case were inter- Rand, 1960; Love and Olafson, 1966). Poser (1956), preted as indicating the presence ofan intramedullary in a review of 234 cases of syringomyelia, found tumour. The correct diagnosis was made in each that the cavity extended into the lumbosacral region case only at operation. in only 12-6% and in only five cases were the Protected by copyright. cavities restricted to the lumbosacral segments. Some authors (Thevenard, 1942; Andre, 1951) CASE REPORTS question the occurrence of syringomyelia in the lower spinal cord. Nevertheless a high incidence CASE 1 (F.T., NO. 179 16 92) A 22-year-old negro male of constitutional defects has been noted among was admitted complaining of weakness and pain in the syringomyelia patients and members of their legs for three years.
    [Show full text]
  • Distance Learning Program Anatomy of the Human Brain/Sheep Brain Dissection
    Distance Learning Program Anatomy of the Human Brain/Sheep Brain Dissection This guide is for middle and high school students participating in AIMS Anatomy of the Human Brain and Sheep Brain Dissections. Programs will be presented by an AIMS Anatomy Specialist. In this activity students will become more familiar with the anatomical structures of the human brain by observing, studying, and examining human specimens. The primary focus is on the anatomy, function, and pathology. Those students participating in Sheep Brain Dissections will have the opportunity to dissect and compare anatomical structures. At the end of this document, you will find anatomical diagrams, vocabulary review, and pre/post tests for your students. The following topics will be covered: 1. The neurons and supporting cells of the nervous system 2. Organization of the nervous system (the central and peripheral nervous systems) 4. Protective coverings of the brain 5. Brain Anatomy, including cerebral hemispheres, cerebellum and brain stem 6. Spinal Cord Anatomy 7. Cranial and spinal nerves Objectives: The student will be able to: 1. Define the selected terms associated with the human brain and spinal cord; 2. Identify the protective structures of the brain; 3. Identify the four lobes of the brain; 4. Explain the correlation between brain surface area, structure and brain function. 5. Discuss common neurological disorders and treatments. 6. Describe the effects of drug and alcohol on the brain. 7. Correctly label a diagram of the human brain National Science Education
    [Show full text]
  • Split Spinal Cord Malformations in Children
    Split spinal cord malformations in children Yusuf Ersahin, M.D., Saffet Mutluer, M.D., Sevgül Kocaman, R.N., and Eren Demirtas, M.D. Division of Pediatric Neurosurgery, Department of Neurosurgery, and Department of Pathology, Ege University Faculty of Medicine, Izmir, Turkey The authors reviewed and analyzed information on 74 patients with split spinal cord malformations (SSCMs) treated between January 1, 1980 and December 31, 1996 at their institution with the aim of defining and classifying the malformations according to the method of Pang, et al. Computerized tomography myelography was superior to other radiological tools in defining the type of SSCM. There were 46 girls (62%) and 28 boys (38%) ranging in age from less than 1 day to 12 years (mean 33.08 months). The mean age (43.2 months) of the patients who exhibited neurological deficits and orthopedic deformities was significantly older than those (8.2 months) without deficits (p = 0.003). Fifty-two patients had a single Type I and 18 patients a single Type II SSCM; four patients had composite SSCMs. Sixty-two patients had at least one associated spinal lesion that could lead to spinal cord tethering. After surgery, the majority of the patients remained stable and clinical improvement was observed in 18 patients. The classification of SSCMs proposed by Pang, et al., will eliminate the current chaos in terminology. In all SSCMs, either a rigid or a fibrous septum was found to transfix the spinal cord. There was at least one unrelated lesion that caused tethering of the spinal cord in 85% of the patients.
    [Show full text]
  • Review Article Meninges: from Protective Membrane to Stem Cell Niche
    Am J Stem Cell 2012;1(2):92-105 www.AJSC.us /ISSN: 2160-4150/AJSC1205003 Review Article Meninges: from protective membrane to stem cell niche Ilaria Decimo1, Guido Fumagalli1, Valeria Berton1, Mauro Krampera2, Francesco Bifari2 1Department of Public Health and Community Medicine, Section of Pharmacology, University of Verona, Italy; 2De- partment of Medicine, Stem Cell Laboratory, Section of Hematology, University of Verona, Italy Received May 16, 2012; accepted May 23, 2012; Epub 28, 2012; Published June 30, 2012 Abstract: Meninges are a three tissue membrane primarily known as coverings of the brain. More in depth studies on meningeal function and ultrastructure have recently changed the view of meninges as a merely protective mem- brane. Accurate evaluation of the anatomical distribution in the CNS reveals that meninges largely penetrate inside the neural tissue. Meninges enter the CNS by projecting between structures, in the stroma of choroid plexus and form the perivascular space (Virchow-Robin) of every parenchymal vessel. Thus, meninges may modulate most of the physiological and pathological events of the CNS throughout the life. Meninges are present since the very early em- bryonic stages of cortical development and appear to be necessary for normal corticogenesis and brain structures formation. In adulthood meninges contribute to neural tissue homeostasis by secreting several trophic factors includ- ing FGF2 and SDF-1. Recently, for the first time, we have identified the presence of a stem cell population with neural differentiation potential in meninges. In addition, we and other groups have further described the presence in men- inges of injury responsive neural precursors. In this review we will give a comprehensive view of meninges and their multiple roles in the context of a functional network with the neural tissue.
    [Show full text]
  • Endoscopic Anatomical Study of the Arachnoid Architecture on the Base of the Skull
    DOI 10.1515/ins-2012-0005 Innovative Neurosurgery 2013; 1(1): 55–66 Original Research Article Peter Kurucz* , Gabor Baksa , Lajos Patonay and Nikolai J. Hopf Endoscopic anatomical study of the arachnoid architecture on the base of the skull. Part I: The anterior and middle cranial fossa Abstract: Minimally invasive neurosurgery requires a Introduction detailed knowledge of microstructures, such as the arach- noid membranes. In spite of many articles addressing The arachnoid was discovered and named by Gerardus arachnoid membranes, its detailed organization is still not Blasius in 1664 [ 22 ]. Key and Retzius were the first who well described. The aim of this study is to investigate the studied its detailed anatomy in 1875 [ 11 ]. This description was topography of the arachnoid in the anterior cranial fossa an anatomical one, without mentioning clinical aspects. The and the middle cranial fossa. Rigid endoscopes were intro- first clinically relevant study was provided by Liliequist in duced through defined keyhole craniotomies, to explore 1959 [ 13 ]. He described the radiological anatomy of the sub- the arachnoid structures in 110 fresh human cadavers. We arachnoid cisterns and mentioned a curtain-like membrane describe the topography and relationship to neurovascu- between the supra- and infratentorial cranial space bearing lar structures and suggest an intuitive terminology of the his name still today. Lang gave a similar description of the arachnoid. We demonstrate an “ arachnoid membrane sys- subarachnoid cisterns in 1973 [ 12 ]. With the introduction of tem ” , which consists of the outer arachnoid and 23 inner microtechniques in neurosurgery, the detailed knowledge arachnoid membranes in the anterior fossa and the middle of the surgical anatomy of the cisterns became more impor- fossa.
    [Show full text]
  • The Strain Rates in the Brain, Brainstem, Dura, and Skull Under Dynamic Loadings
    Mathematical and Computational Applications Article The Strain Rates in the Brain, Brainstem, Dura, and Skull under Dynamic Loadings Mohammad Hosseini-Farid 1,2,* , MaryamSadat Amiri-Tehrani-Zadeh 3, Mohammadreza Ramzanpour 1, Mariusz Ziejewski 1 and Ghodrat Karami 1 1 Department of Mechanical Engineering, North Dakota State University, Fargo, ND 58104, USA; [email protected] (M.R.); [email protected] (M.Z.); [email protected] (G.K.) 2 Department of Orthopedic Surgery, Mayo Clinic, Rochester, MN 55905, USA 3 Department of Computer Science, North Dakota State University, Fargo, ND 58104, USA; [email protected] * Correspondence: [email protected]; Tel.: +1-7012315859 Received: 7 March 2020; Accepted: 5 April 2020; Published: 7 April 2020 Abstract: Knowing the precise material properties of intracranial head organs is crucial for studying the biomechanics of head injury. It has been shown that these biological tissues are significantly rate-dependent; hence, their material properties should be determined with respect to the range of deformation rate they experience. In this paper, a validated finite element human head model is used to investigate the biomechanics of the head in impact and blast, leading to traumatic brain injuries (TBI). We simulate the head under various directions and velocities of impacts, as well as helmeted and unhelmeted head under blast shock waves. It is demonstrated that the strain rates for the brain 1 are in the range of 36 to 241 s− , approximately 1.9 and 0.86 times the resulting head acceleration under impacts and blast scenarios, respectively. The skull was found to experience a rate in the range 1 of 14 to 182 s− , approximately 0.7 and 0.43 times the head acceleration corresponding to impact and blast cases.
    [Show full text]
  • The Development of the Epidural Space in Human Embryos
    Folia Morphol. Vol. 63, No. 3, pp. 273–279 Copyright © 2004 Via Medica O R I G I N A L A R T I C L E ISSN 0015–5659 www.fm.viamedica.pl The development of the epidural space in human embryos Magdalena Patelska-Banaszewska, Witold Woźniak Department of Anatomy, University School of Medical Sciences, Poznań, Poland [Received 25 April 2004; Accepted 25 June 2004] The epidural space is seen in embryos at stage 17 (41 days) on the periphery of the primary meninx. During stage 18 (44 days) the dura mater proper appears and the epidural space is located between this meninx and the perichondrium and contains blood vessels. During the last week of the embryonic period (stages 20–23) the epidural space is evident around the circumference of the spinal cord. On the posterior surface it is found between the dura mater and the me- soderm of the dorsal body wall. Key words: human neuroembryology, primary meninx, epidural space INTRODUCTION horizontal, frontal, and sagittal planes and stained The epidural space lies between the spinal dura according to various methods (chiefly Mallory, hae- mater and the periosteum of the vertebral canal. This matoxylin and eosin and with silver salts). In some periosteum is formed by the outer endosteal layer embryos graphic reconstructions were prepared at of the dura mater. The epidural space contains loose each of the stages investigated. connective tissue, venous plexuses and adipose tis- sue, which is particularly evident in the lumbar re- RESULTS gion [8]. There is some evidence that it is only a po- The primordium of the epidural space appears in tential space [2].
    [Show full text]
  • What to Expect After Having a Subarachnoid Hemorrhage (SAH) Information for Patients and Families Table of Contents
    What to expect after having a subarachnoid hemorrhage (SAH) Information for patients and families Table of contents What is a subarachnoid hemorrhage (SAH)? .......................................... 3 What are the signs that I may have had an SAH? .................................. 4 How did I get this aneurysm? ..................................................................... 4 Why do aneurysms need to be treated?.................................................... 4 What is an angiogram? .................................................................................. 5 How are aneurysms repaired? ..................................................................... 6 What are common complications after having an SAH? ..................... 8 What is vasospasm? ...................................................................................... 8 What is hydrocephalus? ............................................................................... 10 What is hyponatremia? ................................................................................ 12 What happens as I begin to get better? .................................................... 13 What can I expect after I leave the hospital? .......................................... 13 How will the SAH change my health? ........................................................ 14 Will the SAH cause any long-term effects? ............................................. 14 How will my emotions be affected? .......................................................... 15 When should
    [Show full text]
  • A Cellular Atlas of the Developing Meninges Reveals Meningeal Fibroblast Diversity and Function
    bioRxiv preprint doi: https://doi.org/10.1101/648642; this version posted May 24, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 1 2 3 4 Title: A cellular atlas of the developing meninges reveals meningeal fibroblast diversity and function 5 6 Authors: John DeSisto1,2,3,, Rebecca O’Rourke2, Stephanie Bonney1,3, Hannah E. Jones1,3, Fabien 7 Guimiot4, Kenneth L. Jones2 and Julie A. Siegenthaler1,3,5 8 9 1Department of Pediatrics Section of Developmental Biology, 2Department of Pediatrics Section of 10 Section of Hematology, Oncology, Bone Marrow Transplant, 3Cell Biology, Stem Cells and Development 11 Graduate Program, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045 USA, 12 4INSERM UMR 1141, Hôpital Robert Debré, 75019 Paris, France. 13 14 5Corresponding Author: 15 Julie A. Siegenthaler, PhD 16 University of Colorado, School of Medicine 17 Department of Pediatrics 18 12800 East 19th Ave MS-8313 19 Aurora, CO 80045 USA 20 Telephone #: 303-724-3123 21 E-mail: [email protected] 22 23 Key words (3-6 words): brain development, meninges, pial basement membrane, retinoic acid, human 24 meninges bioRxiv preprint doi: https://doi.org/10.1101/648642; this version posted May 24, 2019. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 25 Abstract 26 The meninges, a multilayered structure that encases the CNS, is composed mostly of fibroblasts, 27 along with vascular and immune cells.
    [Show full text]
  • CHAPTER 8 Face, Scalp, Skull, Cranial Cavity, and Orbit
    228 CHAPTER 8 Face, Scalp, Skull, Cranial Cavity, and Orbit MUSCLES OF FACIAL EXPRESSION Dural Venous Sinuses Not in the Subendocranial Occipitofrontalis Space More About the Epicranial Aponeurosis and the Cerebral Veins Subcutaneous Layer of the Scalp Emissary Veins Orbicularis Oculi CLINICAL SIGNIFICANCE OF EMISSARY VEINS Zygomaticus Major CAVERNOUS SINUS THROMBOSIS Orbicularis Oris Cranial Arachnoid and Pia Mentalis Vertebral Artery Within the Cranial Cavity Buccinator Internal Carotid Artery Within the Cranial Cavity Platysma Circle of Willis The Absence of Veins Accompanying the PAROTID GLAND Intracranial Parts of the Vertebral and Internal Carotid Arteries FACIAL ARTERY THE INTRACRANIAL PORTION OF THE TRANSVERSE FACIAL ARTERY TRIGEMINAL NERVE ( C.N. V) AND FACIAL VEIN MECKEL’S CAVE (CAVUM TRIGEMINALE) FACIAL NERVE ORBITAL CAVITY AND EYE EYELIDS Bony Orbit Conjunctival Sac Extraocular Fat and Fascia Eyelashes Anulus Tendineus and Compartmentalization of The Fibrous "Skeleton" of an Eyelid -- Composed the Superior Orbital Fissure of a Tarsus and an Orbital Septum Periorbita THE SKULL Muscles of the Oculomotor, Trochlear, and Development of the Neurocranium Abducens Somitomeres Cartilaginous Portion of the Neurocranium--the The Lateral, Superior, Inferior, and Medial Recti Cranial Base of the Eye Membranous Portion of the Neurocranium--Sides Superior Oblique and Top of the Braincase Levator Palpebrae Superioris SUTURAL FUSION, BOTH NORMAL AND OTHERWISE Inferior Oblique Development of the Face Actions and Functions of Extraocular Muscles Growth of Two Special Skull Structures--the Levator Palpebrae Superioris Mastoid Process and the Tympanic Bone Movements of the Eyeball Functions of the Recti and Obliques TEETH Ophthalmic Artery Ophthalmic Veins CRANIAL CAVITY Oculomotor Nerve – C.N. III Posterior Cranial Fossa CLINICAL CONSIDERATIONS Middle Cranial Fossa Trochlear Nerve – C.N.
    [Show full text]
  • The Spinal Cord Is a Nerve Column That Passes Downward from Brain Into the Vertebral Canal
    The spinal cord is a nerve column that passes downward from brain into the vertebral canal. Recall that it is part of the CNS. Spinal nerves extend to/from the spinal cord and are part of the PNS. Length = about 17 inches Start = foramen magnum End = tapers to point (conus medullaris) st nd and terminates 1 –2 lumbar (L1-L2) vertebra Contains 31 segments à gives rise to 31 pairs of spinal nerves Note cervical and lumbar enlargements. cauda equina (“horse’s tail”) –collection of spinal nerves at inferior end of vertebral column (nerves coming off end of spinal cord) Meninges- cushion and protected by same 3 layers as brain. Extend past end of cord into vertebral canal à spinal tap because no cord A cross-section of the spinal cord resembles a butterfly with its wings outspread (gray matter) surrounded by white matter. GRAY MATTER or “butterfly” = bundles of cell bodies Posterior (dorsal) horns=association or interneurons (incoming somatosensory information) Lateral horns=autonomic neurons Anterior (ventral) horns=cell bodies of motor neurons Central canal-found within gray matter and filled with CSF White Matter: 3 Regions: Posterior (dorsal) white column or funiculi – contains only ASCENDING tracts à sensory only Lateral white column or funiculi – both ascending and descending tracts à sensory and motor Anterior (ventral) white column or funiculi – both ascending and descending tracts à sensory and motor All nerve tracts made of mylinated axons with same destination and function Associated Structures: Dorsal Roots = made
    [Show full text]