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VIEW Open Access Muscle Spindle Function in Healthy and Diseased Muscle Stephan Kröger* and Bridgette Watkins
Kröger and Watkins Skeletal Muscle (2021) 11:3 https://doi.org/10.1186/s13395-020-00258-x REVIEW Open Access Muscle spindle function in healthy and diseased muscle Stephan Kröger* and Bridgette Watkins Abstract Almost every muscle contains muscle spindles. These delicate sensory receptors inform the central nervous system (CNS) about changes in the length of individual muscles and the speed of stretching. With this information, the CNS computes the position and movement of our extremities in space, which is a requirement for motor control, for maintaining posture and for a stable gait. Many neuromuscular diseases affect muscle spindle function contributing, among others, to an unstable gait, frequent falls and ataxic behavior in the affected patients. Nevertheless, muscle spindles are usually ignored during examination and analysis of muscle function and when designing therapeutic strategies for neuromuscular diseases. This review summarizes the development and function of muscle spindles and the changes observed under pathological conditions, in particular in the various forms of muscular dystrophies. Keywords: Mechanotransduction, Sensory physiology, Proprioception, Neuromuscular diseases, Intrafusal fibers, Muscular dystrophy In its original sense, the term proprioception refers to development of head control and walking, an early im- sensory information arising in our own musculoskeletal pairment of fine motor skills, sensory ataxia with un- system itself [1–4]. Proprioceptive information informs steady gait, increased stride-to-stride variability in force us about the contractile state and movement of muscles, and step length, an inability to maintain balance with about muscle force, heaviness, stiffness, viscosity and ef- eyes closed (Romberg’s sign), a severely reduced ability fort and, thus, is required for any coordinated move- to identify the direction of joint movements, and an ab- ment, normal gait and for the maintenance of a stable sence of tendon reflexes [6–12]. -
Nerve Ultrasound in Dorsal Root Ganglion Disorders: Smaller Nerves Lead to Bigger Insights
Clinical Neurophysiology 130 (2019) 550–551 Contents lists available at ScienceDirect Clinical Neurophysiology journal homepage: www.elsevier.com/locate/clinph Editorial Nerve ultrasound in dorsal root ganglion disorders: Smaller nerves lead to bigger insights See Article, pages 568–572 After decades of having to make do with electric stimulation representing the fascicles, bundled together in a large outer cable and recording (i.e. nerve conduction studies, electromyography sheath (van Alfen et al., 2018). and evoked potentials), nerve ultrasound now provides the oppor- Next, it is important to realize what the ratio between axon/ tunity to improve neurodiagnostic patient care by deploying a myelin and connective tissue in a given nerve segment is, and powerful tool to detect neuromuscular pathology in an accurate how that ratio changes from the proximal root to the distal end and patient-friendly way (Mah et al., 2018; Walker et al., 2018). branches (Schraut et al., 2016). Connective tissue elements of the Nerve ultrasound is also increasingly providing neurologists and perineurium and epineurium are relatively sparse at the very prox- clinical neurophysiologists with the opportunity to increase their imal root and plexus levels, with an average connective tissue con- insight in the pathophysiology of peripheral nervous system tent of around 25–30%. Ultrasonographically, this means that roots (PNS) pathology. In this issue of Clinical Neurophysiology, Leadbet- will always look rather black in appearance without much dis- ter and coworkers (Leadbetter et al., 2019) describe the results of cernible fascicular architecture, as the sparseness of connective tis- their study on nerve ultrasound for diagnosing sensory neuronopa- sue elements provides relatively few reflectors to create an image thy in spinocerebellar ataxia type 2 and CANVAS syndrome. -
Inside Your Brain You and Your Brain
Inside your brain You and your brain Many simple and complex psychological functions are mediated by multiple brain regions and, at the same time, a single brain area may control many psychological functions. CC BY Illustration by Bret Syfert 1. Cortex: The thin, folded structure on the outside surface of the brain. 2. Cerebral hemispheres: The two halves of the brain, each of which controls and receives information from the opposite side of the body. 3. Pituitary gland: The ‘master gland’ of the body, which releases hormones that control growth, blood pressure, the stress response and the function of the sex organs. 4. Substantia nigra: The ‘black substance’ contains cells that produce the neurotransmitter dopamine and the pigment melatonin, giving it a black appearance. 5. Hypothalamus: The interface between the brain and pituitary gland. It controls the production and release of hormones. 6. Spinal cord: A large bundle of millions of nerve fibres and neuronal cells, which carries information back and forth between the brain and the body. 7. Medulla oblongata: Controls vital involuntary functions such as breathing and heart rate. 8. Cerebellum: The ‘little brain’ that controls balance and coordinates movements. It’s normally required for learning motor skills, such as riding a bike, and is involved in thought processes. 9. Cranial nerve nuclei: Clusters of neurons in the brain stem. Their axons form the cranial nerves. Your brain underpins who you are. It stores your knowledge and memories, gives you the capacity for thought and emotion, and enables you to control your body. The brain is just one part of the nervous system. -
Electromagnetic Field and TGF-Β Enhance the Compensatory
www.nature.com/scientificreports OPEN Electromagnetic feld and TGF‑β enhance the compensatory plasticity after sensory nerve injury in cockroach Periplaneta americana Milena Jankowska1, Angelika Klimek1, Chiara Valsecchi2, Maria Stankiewicz1, Joanna Wyszkowska1* & Justyna Rogalska1 Recovery of function after sensory nerves injury involves compensatory plasticity, which can be observed in invertebrates. The aim of the study was the evaluation of compensatory plasticity in the cockroach (Periplaneta americana) nervous system after the sensory nerve injury and assessment of the efect of electromagnetic feld exposure (EMF, 50 Hz, 7 mT) and TGF‑β on this process. The bioelectrical activities of nerves (pre‑and post‑synaptic parts of the sensory path) were recorded under wind stimulation of the cerci before and after right cercus ablation and in insects exposed to EMF and treated with TGF‑β. Ablation of the right cercus caused an increase of activity of the left presynaptic part of the sensory path. Exposure to EMF and TGF‑β induced an increase of activity in both parts of the sensory path. This suggests strengthening efects of EMF and TGF‑β on the insect ability to recognize stimuli after one cercus ablation. Data from locomotor tests proved electrophysiological results. The takeover of the function of one cercus by the second one proves the existence of compensatory plasticity in the cockroach escape system, which makes it a good model for studying compensatory plasticity. We recommend further research on EMF as a useful factor in neurorehabilitation. Injuries in the nervous system caused by acute trauma, neurodegenerative diseases or even old age are hard to reverse and represent an enormous challenge for modern medicine. -
Nervous Tissue
Nervous Tissue • Controls and integrates all body activities within limits that maintain life • Three basic functions – sensing changes with sensory receptors • fullness of stomach or sun on your face – interpreting and remembering those changes – reacting to those changes with effectors • muscular contractions • glandular secretions Major Structures of the Nervous System • Brain, cranial nerves, spinal cord, spinal nerves, ganglia, enteric plexuses and sensory receptors Organization of the Nervous System • CNS is brain and spinal cord • PNS is everything else Nervous System Divisions • Central nervous system (CNS) – consists of the brain and spinal cord • Peripheral nervous system (PNS) – consists of cranial and spinal nerves that contain both sensory and motor fibers – connects CNS to muscles, glands & all sensory receptors Subdivisions of the PNS • Somatic (voluntary) nervous system (SNS) – neurons from cutaneous and special sensory receptors to the CNS – motor neurons to skeletal muscle tissue • Autonomic (involuntary) nervous systems – sensory neurons from visceral organs to CNS – motor neurons to smooth & cardiac muscle and glands • sympathetic division (speeds up heart rate) • parasympathetic division (slow down heart rate) • Enteric nervous system (ENS) – involuntary sensory & motor neurons control GI tract – neurons function independently of ANS & CNS Neurons • Functional unit of nervous system • Have capacity to produce action potentials – electrical excitability • Cell body – single nucleus with prominent nucleolus – Nissl -
Build a Neuron
Build a Neuron Objectives: 1. To understand what a neuron is and what it does 2. To understand the anatomy of a neuron in relation to function This activity is great for ALL ages-even college students!! Materials: pipe cleaners (2 full size, 1 cut into 3 for each student) pony beads (6/student Introduction: Little kids: ask them where their brain is (I point to my head and torso areas till they shake their head yes) Talk about legos being the building blocks for a tower and relate that to neurons being the building blocks for your brain and that neurons send messages to other parts of your brain and to and from all your body parts. Give examples: touch from body to brain, movement from brain to body. Neurons are the building blocks of the brain that send and receive messages. Neurons come in all different shapes. Experiment: 1. First build soma by twisting a pipe cleaner into a circle 2. Then put a 2nd pipe cleaner through the circle and bend it over and twist the two strands together to make it look like a lollipop (axon) 3. take 3 shorter pipe cleaners attach to cell body to make dendrites 4. add 6 beads on the axon making sure there is space between beads for the electricity to “jump” between them to send the signal super fast. (myelin sheath) 5. Twist the end of the axon to make it look like 2 feet for the axon terminal. 6. Make a brain by having all of the neurons “talk” to each other (have each student hold their neuron because they’ll just throw them on a table for you to do it.) messages come in through the dendrites and if its a strong enough electrical change, then the cell body sends the Build a Neuron message down it’s axon where a neurotransmitter is released. -
Microglia Control Glutamatergic Synapses in the Adult Mouse Hippocampus
bioRxiv preprint doi: https://doi.org/10.1101/2021.02.01.429096; this version posted February 2, 2021. The copyright holder for this preprint (which was not certified by peer review) is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under aCC-BY-NC-ND 4.0 International license. Microglia control glutamatergic synapses in the adult mouse hippocampus Short title: Microglia and glutamatergic synapses Bernadette Basilico1†*‡, Laura Ferrucci1‡, Patrizia Ratano2‡, Maria T. Golia1, Alfonso Grimaldi3, Maria Rosito3, Valentina Ferretti4, Ingrid Reverte1,5, Maria C. Marrone6, Maria Giubettini3,7, Valeria De Turris3, Debora Salerno3, Stefano Garofalo1, Marie-Kim St-Pierre8, Micael Carrier8, Massimiliano Renzi1, Francesca Pagani3, Marcello Raspa9, Ferdinando Scavizzi9, Cornelius T. Gross10, Silvia Marinelli5, Marie E. Tremblay8,11, Daniele Caprioli1,5, Laura Maggi1, Cristina Limatola1,2, Silvia Di Angelantonio1,3§, Davide Ragozzino1,5*§ 1Department of Physiology and Pharmacology, Sapienza University of Rome, Rome, Italy. 2IRCCS Neuromed, Via Atinese 18, 86077, Pozzilli, IS, Italy. 3Center for Life Nanoscience, Istituto Italiano di Tecnologia, Rome, Italy. 4Dipartimento di Biologia e Biotecnologie "Charles Darwin", Sapienza University of Rome, Rome, Italy. 5Santa Lucia Foundation (IRCCS Fondazione Santa Lucia), Rome, Italy. 6European Brain Research Institute-Rita Levi Montalcini, Rome, Italy. 7CrestOptics S.p.A., Via di Torre Rossa 66, 00165 Rome, Italy. 8Centre de Recherche du CHU de Québec, Axe Neurosciences Québec, QC, Canada; Département de médecine moléculaire, Université Laval Québec, QC, Canada. 9National Research Council, Institute of Biochemistry and Cell Biology (CNR- IBBC/EMMA/Infrafrontier/IMPC), International Campus “A. Buzzati-Traverso”, Monterotondo (Rome) Italy. -
Neurons and Glia
CHAPTER TWO Neurons and Glia INTRODUCTION THE NEURON DOCTRINE The Golgi Stain Cajal’s Contribution BOX 2.1 OF SPECIAL INTEREST: Advances in Microscopy THE PROTOTYPICAL NEURON The Soma The Nucleus Neuronal Genes, Genetic Variation, and Genetic Engineering BOX 2.2 BRAIN FOOD: Expressing One’s Mind in the Post-Genomic Era BOX 2.3 PATH OF DISCOVERY: Gene Targeting in Mice, by Mario Capecchi Rough Endoplasmic Reticulum Smooth Endoplasmic Reticulum and the Golgi Apparatus The Mitochondrion The Neuronal Membrane The Cytoskeleton Microtubules BOX 2.4 OF SPECIAL INTEREST: Alzheimer’s Disease and the Neuronal Cytoskeleton Microfilaments Neurofilaments The Axon The Axon Terminal The Synapse Axoplasmic Transport BOX 2.5 OF SPECIAL INTEREST: Hitching a Ride with Retrograde Transport Dendrites BOX 2.6 OF SPECIAL INTEREST: Intellectual Disability and Dendritic Spines CLASSIFYING NEURONS Classification Based on Neuronal Structure Number of Neurites Dendrites Connections Axon Length Classification Based on Gene Expression BOX 2.7 BRAIN FOOD: Understanding Neuronal Structure and Function with Incredible Cre GLIA Astrocytes Myelinating Glia Other Non-Neuronal Cells CONCLUDING REMARKS 23 © Jones & Bartlett Learning, LLC. NOT FOR SALE OR DISTRIBUTION. 24 PART ONE FOUNDATIONS INTRODUCTION All tissues and organs in the body consist of cells. The specialized func- tions of cells and how they interact determine the functions of organs. The brain is an organ—to be sure, the most sophisticated and complex organ that nature has devised. But the basic strategy for unraveling its functions is no different from that used to investigate the pancreas or the lung. We must begin by learning how brain cells work individually and then see how they are assembled to work together. -
Spinal Nerves, Ganglia, and Nerve Plexus Spinal Nerves
Chapter 13 Spinal Nerves, Ganglia, and Nerve Plexus Spinal Nerves Posterior Spinous process of vertebra Posterior root Deep muscles of back Posterior ramus Spinal cord Transverse process of vertebra Posterior root ganglion Spinal nerve Anterior ramus Meningeal branch Communicating rami Anterior root Vertebral body Sympathetic ganglion Anterior General Anatomy of Nerves and Ganglia • Spinal cord communicates with the rest of the body by way of spinal nerves • nerve = a cordlike organ composed of numerous nerve fibers (axons) bound together by connective tissue – mixed nerves contain both afferent (sensory) and efferent (motor) fibers – composed of thousands of fibers carrying currents in opposite directions Anatomy of a Nerve Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Epineurium Perineurium Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Endoneurium Nerve Rootlets fiber Posterior root Fascicle Posterior root ganglion Anterior Blood root vessels Spinal nerve (b) Copyright by R.G. Kessel and R.H. Kardon, Tissues and Organs: A Text-Atlas of Scanning Electron Microscopy, 1979, W.H. Freeman, All rights reserved Blood vessels Fascicle Epineurium Perineurium Unmyelinated nerve fibers Myelinated nerve fibers (a) Endoneurium Myelin General Anatomy of Nerves and Ganglia • nerves of peripheral nervous system are ensheathed in Schwann cells – forms neurilemma and often a myelin sheath around the axon – external to neurilemma, each fiber is surrounded by -
The Peripheral Nervous System
The Peripheral Nervous System Dr. Ali Ebneshahidi Peripheral Nervous System (PNS) – Consists of 12 pairs of cranial nerves and 31 pairs of spinal nerves. – Serves as a critical link between the body and the central nervous system. – peripheral nerves contain an outermost layer of fibrous connective tissue called epineurium which surrounds a thinner layer of fibrous connective tissue called perineurium (surrounds the bundles of nerve or fascicles). Individual nerve fibers within the nerve are surrounded by loose connective tissue called endoneurium. Cranial Nerves Cranial nerves are direct extensions of the brain. Only Nerve I (olfactory) originates from the cerebrum, the remaining 11 pairs originate from the brain stem. Nerve I (Olfactory)- for the sense of smell (sensory). Nerve II (Optic)- for the sense of vision (sensory). Nerve III (Oculomotor)- for controlling muscles and accessory structures of the eyes ( primarily motor). Nerve IV (Trochlear)- for controlling muscles of the eyes (primarily motor). Nerve V (Trigeminal)- for controlling muscles of the eyes, upper and lower jaws and tear glands (mixed). Nerve VI (Abducens)- for controlling muscles that move the eye (primarily motor). Nerve VII (Facial) – for the sense of taste and controlling facial muscles, tear glands and salivary glands (mixed). Nerve VIII (Vestibulocochlear)- for the senses of hearing and equilibrium (sensory). Nerve IX (Glossopharyngeal)- for controlling muscles in the pharynx and to control salivary glands (mixed). Nerve X (Vagus)- for controlling muscles used in speech, swallowing, and the digestive tract, and controls cardiac and smooth muscles (mixed). Nerve XI (Accessory)- for controlling muscles of soft palate, pharynx and larynx (primarily motor). Nerve XII (Hypoglossal) for controlling muscles that move the tongue ( primarily motor). -
PN1 (Midha) Microanatomy of Peripheral Nerves-Part1.Pdf
Peripheral Nerve Basics • Consist of processes of cell bodies found in the DRG, anterior horn, and autonomic ganglia • Organized by several distinct connective tissue layers – the epineurium, perineurium, and endoneurium • Vascular supply provided by the vasa nervorum Peripheral Nerve Basics • Neuronal processes bound into fascicles by perineurium • Fascicles bound into nerves by epineurium • Endoneurium is a division of the perineurium which form thin layers of connective tissue surrounding neuronal fibers in a fascicle Sural nerve in cross-section Epineurium • Loose areolar tissue with sparse, longitudinally-oriented collagen fibers • Some elastic fibers where epineurium abuts perineurium • Able to accommodate a significant amount of nerve stretching and movement • Increases in thickness where nerves cross joints • Constitutes an increasing proportion of nerves as they increase in size • Epineurial fat helps cushion nerves from compressive injury • Decreased epineurial fat found in patients with diabetes Perineurium • Cellular component composed of laminated fibroblasts of up to 15 layers in thickness which are bounded by a basal lamina • Semi-permeable: inner lamellae have tight junctions, providing a barrier to intercellular transport of macromolecules – Tight junctions can be loosened with topical anaesthetics and with osmotic change Perineurium • Exhibits a slightly positive internal pressure – Fascicular contents herniate upon perineurial injury • Under tension longitudinally – Nerve segment shortens upon transection – may complicate surgical repair as nerve can be stretched only approximately 10% before being inhibited by collagen Endoneurium • Intrafascicular connective tissue consisting of a collagenous matrix in the interstitial space • Develops into partitions of dense connective tissue between diverging fascicles and eventually becomes perineurium when the fascicles separate • Collagen fibers are longitudinally-oriented and run along nerve fibers and capillaries. -
Nerve and Nerve Injuries” Sunderland : 50 Years Later
2019 Nerve and Nerve Injuries” Sunderland : 50 years later Faye Chiou Tan, MD Professor, Dir. EDX, H. Ben Taub PMR, Baylor College of Medicine Chief PMR, Dir. EDX, Harris Health System 2019 Financial Disclosure • Elsevier Book Royalties for “EMG Secrets” textbook • Revance, consultation panel 2019 Warning Videotaping or taking pictures of the slides associated with this presentation is prohibited. The information on the slides is copyrighted and cannot be used without permission and author attribution. Introduction – Sydney Sunderland was Professor of Experimental Neurology at the University of Melbourne. – His textbook “Nerve and Nerve lnjuries” published in 1968 is no longer in print (copies $1000 on the internet) – Here is a review as relates to new technology: Ultrahigh frequency musculoskeletal ultrasound Part I – I. Anatomic and physiologic features of A. Peripheral nerve fibers B. Peripheral nerve trunks I.A. Peripheral nerve fibers – Axoplasm – Increased flow of cytoplasm from cell body into axons during electrical stimulation (Grande and Richter 1950) – Although overall proximal to distal axoplasmic flow, the pattern of streaming in the axon is bidirectional and faster (up to 3-7 cm/day) (Lubinska 1964). I. A. Peripheral nerve fibers – Sheath – Myelinated – Length of internode elongates with growth (Vizoso and Young 1948, Siminoff 1965) – In contrast, remyelination in adults produce short internodes of same length (Leegarrd 1880, Young 1945,…) – Incisures of Schmidt-Lantermann are clefts conical clefts that open when a nerve trunk is stretched thereby preventing distortion of myelin. (Glees, 1943) Schmidt-Lantermann Clefts Sunderland S. Nerve and Nerve Injuries, Sunderland, Livingstone,LTD, Edinburgh/London, 1968, p. 8 I. A.