DOCSLIB.ORG

Reflex General Function of the Nervous System (NS)

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Physiology of the central nervous system Motor division of the CNS Reflex General function of the nervous system (NS) Nervous system -communication network of neurons that allows the organism to interact with the environment (external, internal) • main function: regulation of body functions • purpose: adaptation to changes - maintenance http://www.alz.org/braintour/images/neuron_forest.jpg of homeostasis and survival 1. Peripheral NS 2. Central nervous system Levels of the CNS • Spinal cord - conducts sensory information to the brain - conducts motor information to the effector organs - serves as a simple regulatory centre (reflexes) - damage of the spinal cord breaks down the connection between periphery and higher centres – serious consequences • Brain - subcortical level - control of involuntary and subconscious functions - brain cortex - control of voluntary functions - control of lower levels of CNS - site of cognitive (higher) functions: memory, learning, thinking Peripheral nervous system (PNS) - transmits information from periphery to the central nervous system and vice versa Includes - cranial nerves – originate in brain (I – XII) - spinal nerves - originate in spinal cord (C1, C2...Th,..L, S..) Components A. afferent (sensory) nervous system (incoming to CNS) B. efferent (motor) nervous system (outgoing from CNS) a. somatic nervous system (transmit impulses to skeletal muscle) b. autonomic nervous system (transmit impulses to smooth muscles, cardiac muscle and glands) I. sympathetic division (fight or flight) II. parasympathetic division (rest and repair) Motor functions and their regulation Spinal reflexes - simple movements – reflex movements Brainstem – posture control, hand and eye movements Cerebellum - making movements „smooth“ - precisely regulates the sequence and duration of the elementary movements of each of these segments Basal ganglia - regulation of well co-ordinated voluntary movements - cognitive control of voluntary movements (e.g. running away from a dangerous animal) Brain cortex – motor areas (primary, premotor, supple- mentary motor) decision about voluntary movements Knee jerk – the patellar reflex - tap on the tendon of m. quadriceps femoris - the leg makes a „kick“ (extension in knee joint occurs) Reflex • definition: predictable, quick, stereotyped and involuntary response to stimulus • action that results from passing a nerve impulse over a reflex arc • „lowest level“ of regulation of motor functions Reflex arc – the basic circuit that underlies a reflex: 1. sensory receptor – gathers stimuli 2. afferent nervous fibre – signal transduction into CNS 3. reflex (integration) centre – processes information 4. efferent nerve fibre – transduction of response 5. effector (muscle, gland)– performance, response to the stimulus Spinal reflex arc Classification of reflexes – with respect to: A/ Count of synapses: 1. Monosynaptic - 1 synapse in the reflex arc 2. Polysynaptic = 2 or more synapses in reflex arc https://s-media-cache-ak0.pinimg.com/originals/a6/41/3f/a6413f649558834e5541fb7e03124f54.jpg Classification of reflexes – with respect to: B/ Type of sensory receptor Exteroceptive – receptor in the reflex arc is an exteroceptor (gathers stimuli from external environment) Proprioceptive – receptor in the reflex arc is an proprioceptor (gathers stimuli about position of the body) Interoceptive – receptor in the reflex arc is an proprioceptor (gather stimuli from internal environment) C/ Integration (reflex) centre Cranial – centre in nuclei of the cranial nerves Spinal – centre in the spinal cord Extracentral – integration centre in autonomic ganglia D/ Effector Somatic – effector: skeletal muscle Autonomic (visceral) – effector: cardiac muscle, smooth muscle, gland E/ Origin Inborn – related to locomotion, defence, food intake, sexual behaviour Acquired – develop during life Spinal reflexes Spinal reflexes include - the muscle stretch reflex - the Golgi tendon reflex - the crossed extensor reflex - the withdrawal reflex Muscle stretch reflexes (myotatic) • monosynaptic • spinal reflexes – refelex centre in the spinal cord • example: knee jerk • involved in regulation of movement, muscle tone and posture – motor control • in part conscious • to major extent - subconscious reflex or automatic action – includes spinal reflexes • both receptor and effector are in the same muscle • types of sensory receptors involved in spinal reflexes: – a muscle spindle – Golgi tendon organs The muscle spindle •a stretch receptor in a muscle •a bundle of modified muscle fibres encased in a capsule Polar parts of the muscle spindle - composed of intrafusal fibres that are contractile (can respond to a stimulation by contraction) Central part of the muscle spindle - fibres non contractile – does not respond to stimulation by a contraction - can be passively stretched - a sensory nerve is wrapped around the fibres • adequate stimulus for the muscle spindle: muscle stretch - potential is transmitted via the sensory nerve stretch muscle to the reflex centre c • response – contraction of the extrafusal c muscle fibres of the same muscle Muscle stretch reflexes – reflex arc • tapping on the muscle tendon (of different muscles) passive prolongation of the muscle and also of the muscle spidle = stimulation(1) • action potential is transmitted by afferent fibre (2) • afferent fibre enters spinal cord through posterior roots c c • afferent fibre synapses with efferent fibre (a – motoneuron) • synapse = integration centre (3) (information is processed) • action potential is transmitted by efferent fibre (a – motoneuron) Tap the tendon, also the muscle and muscle into muscles (via the motor endplate) (4) spindle is prolonged • muscle contraction occurs (5-response) - this is seen as movement (muscle contraction) Golgi tendon organ • a proprioceptive sensory receptor • located at the insertion of skeletal muscle fibers into the tendons of skeletal muscle • made up of strands of collagen connected at one end to the muscle and at the other with the tendon • when the muscle contracts, the collagen fibrils are pulled tight, and this activates the Golgi tendon organ afferent • it detects tension of the muscle The Golgi tendon reflex (inverse myotatic reflex, polysynaptic) - receptor: Golgi tendon organ (can be stimulated by very strong contraction or stretching) - signal transmitted via afferent nerve fibre and by interneurons (inhibitory) in spinal cord to alpha motorneurons - efferent fibre: alpha motoneuron – it gets inhibited !!! - response: muscle relaxation (the same muscle where the receptor is located) - function: protection against rupture of the muscle https://acewebcontent.azureedge.net/blogs/blog-examprep-031615-2.png Withdrawal reflex (polysynaptic) -stimulus causes response in both flexors and extensors of the same side: 1. activation of alpha motoneurons of the ipsilateral flexor muscles, 2. at the same time inhibits alpha motoneurons that supply antagonistic extensor muscles - example: when touching a hot object – contraction of flexors and relaxation of extensors causes removing the hand Crossed extension reflex – polysynaptic - a stimulus causes response on both sides in bots extensors and flexors: 1.activation of alpha motoneurons of the ipsilateral flexor muscles 2.inhibits alpha motoneurons that supply antagonistic extensor muscles - the opposite pattern occurs on contralateral side 3.flexors are inhibited 4.extensors are stimulated - example: when a person steps on a nail, the leg that is stepping on the nail pulls away, while the other leg takes the weight of the whole body- reflex enhances postural support - example: locomotor pattern generator Spinal cord • segmental organization • segments (levels) of the spinal cord contain regulatory circuits involved in control of the movements of a particular region of the body • muscle stretch reflexes have their inegration centres in different segments of the spinal cord Muscles in axial parts of the body limbs (a motoneurons medial part) (a motoneurons -lateral part) = somatotopic organization Examination of reflexes in a human • basic examination in neurology • indicates the function of reflex arc (and all its components) • reflex - stereotypic reaction = predicted response • normoreflexia – normal reflex response on a stimulus • abnormal response indicates disorder in a part of reflex arc Types of abnormal results: • hyperreflexia (or clonus) – hyperactive reflex • hyporeflexia – diminished reflex • areflexia – absence of response • abnormal reflex – the response on the stimulation is abnormal Task: Examination of reflexes in a human Principle • sensory receptors are stimulated • the reflex response on stimulation is observed and evaluated Procedure • the patient is in sitting or lying position (depends on the reflex) • sensory receptors are stimulated by a reflex hammer, cotton, light, needle (depends on the reflex that we want to examine) • examine following reflexes (see next slides) Reflex examination video https://www.youtube.com/watch?v=eqOpNQH09pA Proprioceptive (deep tendon) reflexes - sensory receptor – in muscle, tendon • Masseter reflex (n V) S: tap on a spatula put on the lower jaw (mouth is moderately open) R: closing the mouth • Naso-palpebral reflex (n V,VII) S: tap on the nasal base R: closing of eyelids • Biceps reflex (C5) S: tap on lacerus fibrosus m. bic. brachii R: flexion of the forearm • Triceps reflex (C7) S: tap on olecranon ulnae R: extension of the forearm • Styloradial (brachioradial)reflex (C7) S: tap on proc. styloideus radii
Recommended publications
  • Download Edissertation

    Download Edissertation

    The Human Nociceptive Withdrawal Reflex The Human Nociceptive Withdrawal Reflex Improved Understanding and Optimization of Reflex Elicitation and Recording PhD Thesis by Ken Steffen Frahm Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, Denmark ISBN 978-87-92982-69-8 (paperback) ISBN 978-87-92982-68-1 (e-book) Published, sold and distributed by: River Publishers Niels Jernes Vej 10 9220 Aalborg Ø Denmark Tel.: +45369953197 www.riverpublishers.com Copyright for this work belongs to the author, River Publishers have the sole right to distribute this work commercially. All rights reserved c 2013 Ken Steffen Frahm. No part of this work may be reproduced, stored in a retrieval system, or trans- mitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without prior written permission from the Publisher. Contents Preface vii Acknowledgements ix English summary xi Danish summary xiii List of abbreviations xv Introduction 1 1.1 The Nociceptive Withdrawal Reflex ......................................... 2 Aims 7 2.1 Overview of study aims ............................................................. 9 2.2 Papers ...................................................................................... 10 Methods 11 3.1 Reflex monitoring (study I) ..................................................... 11 3.2 Noxious stimulation (study I & II) .......................................... 15 3.3 Mapping the neural activation in the sole of the foot (study
  • Focusing on the Re-Emergence of Primitive Reflexes Following Acquired Brain Injuries

    Focusing on the Re-Emergence of Primitive Reflexes Following Acquired Brain Injuries

    33 Focusing on The Re-Emergence of Primitive Reflexes Following Acquired Brain Injuries Resiliency Through Reconnections - Reflex Integration Following Brain Injury Alex Andrich, OD, FCOVD Scottsdale, Arizona Patti Andrich, MA, OTR/L, COVT, CINPP September 19, 2019 Alex Andrich, OD, FCOVD Patti Andrich, MA, OTR/L, COVT, CINPP © 2019 Sensory Focus No Pictures or Videos of Patients The contents of this presentation are the property of Sensory Focus / The VISION Development Team and may not be reproduced or shared in any format without express written permission. Disclosure: BINOVI The patients shown today have given us permission to use their pictures and videos for educational purposes only. They would not want their images/videos distributed or shared. We are not receiving any financial compensation for mentioning any other device, equipment, or services that are mentioned during this presentation. Objectives – Advanced Course Objectives Detail what primitive reflexes (PR) are Learn how to effectively screen for the presence of PRs Why they re-emerge following a brain injury Learn how to reintegrate these reflexes to improve patient How they affect sensory-motor integration outcomes How integration techniques can be used in the treatment Current research regarding PR integration and brain of brain injuries injuries will be highlighted Cases will be presented Pioneers to Present Day Leaders Getting Back to Life After Brain Injury (BI) Descartes (1596-1650) What is Vision? Neuro-Optometric Testing Vision writes spatial equations
  • Central Nervous System

    Central Nervous System

    MCQ : Central Nervous System Section 1 General Functional Organization of the Nervous System 1 ) The central nervous system includes all the following components, except :- a- spinal cord b- medulla oblongata c- autonomic ganglia d- diencephalon 2 ) The central nervous system is connected with the peripheral nervous system by all the following types of nerve fibers, except :- a- postganglionic autonomic fibers b- preganglionic autonomic fibers c- somatic motor fibers d- autonomic sensory fibers 3 ) The sensory system is involved in all the following, except :- a- initiation of reflex movements b- initiation of voluntary movements c- learning processes d- initiation of emotional responses 1 MCQ : Central Nervous System Section 2 Sensory System and Sensory Receptors 1) The two-element sensory receptors differ from other types of receptors in being:- a- more numerous b- more widely spread in the body c- more sensitive d- composed of specialized cells at the sensory nerve terminals 2) Sensory receptors are classified functionally according to the following criteria, except :- a- their location in the body b- the nature of tissues in which they are found c- the nature of stimuli acting on them d- their connection with cerebral coretx 3) Most sensory receptors :- a- are stimulated by different types of stimuli b- are stimulated only by specific stimuli c- posses a high threshold for their specific stimuli d- only ‘b’ and ‘c’ are correct 4) A specific stimulus produces a receptor potential by :- a- inhibiting Na + influx into receptor b- inhibiting
  • Level Diagnosis of Cervical Compressive Myelopathy: Signs, Symptoms, and Lesions Levels

    Level Diagnosis of Cervical Compressive Myelopathy: Signs, Symptoms, and Lesions Levels

    Elmer Press Original Article J Neurol Res • 2013;3(5):135-141 Level Diagnosis of Cervical Compressive Myelopathy: Signs, Symptoms, and Lesions Levels Naoki Kasahata ficult to accurately localize the lesion before radiographic Abstract diagnosis. However, neurological level diagnosis of spinal cord is important for accurate lesion-specific level diagnosis, Background: To elucidate signs and symptoms corresponding to patients’ treatment, avoiding diagnostic error, differential di- each vertebral level for level-specific diagnoses. agnosis, and especially for accurate level diagnosis of other nonsurgical myelopathies. Moreover, level diagnosis should Methods: We studied 106 patients with cervical compressive my- be considered from multiple viewpoints. Therefore, we in- elopathy. Patients who showed a single compressive site on mag- tend to make level diagnosis of myelopathy more accurate. netic resonance imaging (MRI) were selected, and signs, symp- Previously, lesion-specific level diagnoses by determin- toms, and the levels of the MRI lesions were studied. ing a sensory disturbance area or location of numbness in Results: Five of 12 patients (41.7%) with C4-5 intervertebral level the hands had the highest accuracy [1, 2]. Previous stud- lesions showed decreased or absent biceps and brachioradialis re- ies reported that C3-4 intervertebral level lesions showed flexes, while 4 of these patients (33.3%) showed generalized hyper- increased or decreased biceps reflexes, deltoid weakness, reflexia. In comparison, 5 of 24 patients (20.8%) with C5-6 inter- and sensory disturbance of arms or forearms [1, 3, 4], while vertebral level lesions showed decreased or absent triceps reflexes; C4-5 intervertebral level lesions showed decreased biceps however, 9 of these patients (37.5%) showed decreased or absent reflexes, biceps weakness, and sensory disturbance of hands biceps and brachioradialis reflexes.
  • What's the Connection?

    What's the Connection?

    WHAT’S THE CONNECTION? Sharon Winter Lake Washington High School Directions for Teachers 12033 NE 80th Street Kirkland, WA 98033 SYNOPSIS Students elicit and observe reflex responses and distinguish between types STUDENT PRIOR KNOWL- of reflexes. They then design and conduct experiments to learn more about EDGE reflexes and their control by the nervous system. Before participating in this LEVEL activity students should be able to: Exploration, Concept/Term Introduction Phases ■ Describe the parts of a Application Phase neuron and explain their functions. ■ Distinguish between sensory and motor neurons. Getting Ready ■ Describe briefly the See sidebars for additional information regarding preparation of this lab. organization of the nervous system. Directions for Setting Up the Lab General: INTEGRATION Into the Biology Curriculum ■ Make an “X” on the chalkboard for the teacher-led introduction. ■ Health ■ Photocopy the Directions for Students pages. ■ Biology I, II ■ Human Anatomy and Teacher Background Physiology A reflex is an involuntary neural response to a specific sensory stimulus ■ AP Biology that threatens the survival or homeostatic state of an organism. Reflexes Across the Curriculum exist in the most primitive of species, usually with a protective function for ■ Mathematics animals when they encounter external and internal stimuli. A primitive ■ Physics ■ example of this protective reflex is the gill withdrawal reflex of the sea slug Psychology Aplysia. In humans and other vertebrates, protective reflexes have been OBJECTIVES maintained and expanded in number. Examples are the gag reflex that At the end of this activity, occurs when objects touch the sides students will be able to: or the back of the throat, and the carotid sinus reflex that restores blood ■ Identify common reflexes pressure to normal when baroreceptors detect an increase in blood pressure.
  • The Leg Cross Flexion-Extension Reflex: Biomechanics, Neurophysiology, MNRI® Assessment, and Repatterning

    The Leg Cross Flexion-Extension Reflex: Biomechanics, Neurophysiology, MNRI® Assessment, and Repatterning

    Po R t a l t o n e u R o d e ve l o P m e n t a n d le a R n i n g t h e o R y a n d h i s t o R y o f m n R i ® R e f l e x i n t e g R a t i o n The Leg Cross Flexion-Extension Reflex: Biomechanics, Neurophysiology, MNRI® Assessment, and Repatterning Elvin Akhmatov, MA, Ph.D. Student, Orlando, FL, USA; Jakub Buraczewski, PT, MNRI® Core Specialist; Denis Masgutov, Director of SMEI , Poland Introduction wo separate reflexes, Phillipson’s Withdrawal and Leg Cross Flexion-Extension, are eas- ily confused because they have similar motor Tpatterns and are elicited by stimuli that can appear to be alike and usually manifest at the same time. The authors’ purpose is to distinguish clearly between these two reflexes and to present detailed information on the one they refer to as the Leg Cross Flexion-Extension Reflex. The other reflex, often con- Elvin Akhmatov Jakub Buraczewski Denis Masgutov fused with Leg Cross Flexion-Extension, goes by sev- eral names: Phillipson’s Withdrawal, Phillipson’s Leg Flexion, Crossed Extensor, and Leg Withdrawal Reflex, among others. For clarity in this paper, the other reflex will be referred to as Phillipson’s Withdrawal. On the neurophysiological level, these two reflex patterns present the work of two different nerve tracts – tactile and proprioceptive, activated and processed by different receptors. The Leg Cross Flexion-Extension Reflex is extremely important for overall sensory-motor integration, mo- tor programing and control.
  • Reflex Testing in the Laboratory

    Reflex Testing in the Laboratory

    Reflex Testing in The Laboratory Introductory Background Reflex testing is another way of obtaining information about a patient by health care personnel. Many of us are acquainted with some reflexes by virtue of having physical exams, e.g., patellar reflex (knee jerk), biceps, triceps, corneal and Achilles’ tendon reflex. This section deals with, essentially, circuitry of a biological nature. In order to understand this circuitry, it's important to have a fundamental grasp of the "parts" that make up this circuitry. The graphic, below, provides us with an introduction to this concept: A sensory (or afferent; AH fair unt) neuron picks up input (#1, above) and sends it to the spinal cord (#3, above). The portion of a neuron that brings the signal to the cell body is called the dendrite; the portion that sends the signal away from the cell body is called an axon (#5, above). When axons and dendrites from other cells have to communicate, they do so through a microscopic space called a synapse. In some instances, input has to be sent to the brain for interpretation. In others, it's interpreted right in the spinal cord and signals are sent out (motor or efferent; EE fair unt) to the effector organ. In simple stretch reflexes, only two neurons are involved: sensory and motor, graphic, above. In this figure, a stretch reflex is illustrated. The way it works is in this manner: 1) a tendon is stimulated (in this illustration by a reflex hammer), 2) the spindle (blue coil in the diagram) detects this stimulus and sends the input to the cord, 3) the information crosses one synapse (mono-synaptic) to a motor neuron that sends output to the spindle (green coil in diagram) and the muscle contracts.
  • Physiology and Pathophysiology 2018/2019 Dental Medicine Examination Synopsis in Physiology

    Physiology and Pathophysiology 2018/2019 Dental Medicine Examination Synopsis in Physiology

    Medical University of Varna Department of Physiology and Pathophysiology 2018/2019 Dental medicine Examination Synopsis in Physiology Theoretical exam 1. Homeostasis. Control systems of the body – characteristics. Negative feedback mechanism. 2. Cell membranes. Transport of substances through cell membranes. 3. Membrane potential. Resting membrane potential of nerves. 4. Nerve action potential. Propagation of the action potential. Conduction velocity. 5. Signal transmission in nerve fibers. Excitation - the process of eliciting the action potential. Threshold for excitation, refractory period. Inhibition of excitability. 6. Organization and functions of the nervous system. Types of synapses. Electrical synapses. 7. Characteristics of transmission in chemical synapses. 8. Synaptic transmitters. Membrane receptors. 9. Generation of postsynaptic potentials. Generation of action potentials in the axon. Neuronal inhibition - types. Neuroglia. 10. Characteristics of postsynaptic potentials. Spatial and temporal summation in neurons. "Facilitation" of neurons. Characteristics of synaptic transmission. 10. Transmission and processing of signals in neuronal circuits. Convergence, divergence, reverberating circuits. Reflexes - types. 11. Organization of the autonomic nervous system. Location of autonomic ganglia. Characteristics of sympathetic and parasympathetic function - transmitters. 12. Characteristics of sympathetic and parasympathetic function - receptors. 13. Sympathetic or parasympathetic tone. Denervation effects. Autonomic reflexes.
  • Neuropsychiatry Block Stretch Reflex and Golgi Tendon Reflex

    Neuropsychiatry Block Stretch Reflex and Golgi Tendon Reflex

    NeuroPsychiatry Block Stretch reflex and Golgi Tendon Reflex By Prof. Faten zakareia Physiology Department , College of Medicine , King Saud University 2017 Email: [email protected] Ext:52736 NeuroPsychiatryBlock Motor Functions of the Spinal Cord, The cord Reflexes Chapter 55 (Guyton & Hall) -Reference book/Ganong review of medical physiology • Objectives: Upon completion of this lecture, students are expected to : - Describe the stretch reflex and ts icomponents - Describe the structure and function of the muscle spindle - Differentiate between primary and secondary afferent fibres of muscle spindle, Intrafusal nuclear bag &nuclear chain fibers - Differentiate between the Dynamic gamma efferent and Trail endings discharge and their functional role - Differentiate between static and dynamic stretch reflex& damping mechanism - Describe muscle tone and its abnormalities - Disscuss spinal and supraspinal regulation of the stretch reflex - Describe the components of the inverse stretch reflex (golgi tendon reflex)and its function THE STRETCH REFLEX REFLEX STRETCH (MYOTACTIC) REFLEX https://musom.marshall.edu/anatomy/grosshom/allppt/pdf/Spinalreflexes.pdf CLINICAL TEST | RAPID STRETCH OF MUSCLE (TAP ON MUSCLE TENDON) STIMULUS RESPONSE STRETCHED MUSCLE CONTRACT RAPIDLY (I.E. KNEE JERK) SENSORY MUSCLE SPINDLE PRIMARY RECEPTOR SYNAPSES MONOSYNAPTIC INVOLVED EFFECTS ON CONTRACTS (+) SAME MUSCLE AND SYNERGISTIC MUSCLES MUSCLE OTHER EFFECTS RELAXES (-) ANTAGONISTIC MUSCLE FUNCTION AIDS IN MAINTAINING POSTURE, AVOID MUSCLE RUPTURE,COUNTERS SUDDEN
  • The Phenomenon of Multiple Stretch Reflexes

    The Phenomenon of Multiple Stretch Reflexes

    Henry Ford Hospital Medical Journal Volume 34 Number 1 Article 6 3-1986 The Phenomenon of Multiple Stretch Reflexes Robert D. Teasdall Follow this and additional works at: https://scholarlycommons.henryford.com/hfhmedjournal Part of the Life Sciences Commons, Medical Specialties Commons, and the Public Health Commons Recommended Citation Teasdall, Robert D. (1986) "The Phenomenon of Multiple Stretch Reflexes," Henry Ford Hospital Medical Journal : Vol. 34 : No. 1 , 31-36. Available at: https://scholarlycommons.henryford.com/hfhmedjournal/vol34/iss1/6 This Article is brought to you for free and open access by Henry Ford Health System Scholarly Commons. It has been accepted for inclusion in Henry Ford Hospital Medical Journal by an authorized editor of Henry Ford Health System Scholarly Commons. The Phenomenon of Multiple Stretch Reflexes Robert D. Teasdall, MD* Multiple stretch reflexes occur in muscles adjacent to or remote from the tap. The response may be ipsilateral or bilateral. These reflexes are encountered not only in normal subjects with brisk stretch reflexes but particularly in patients with lesions of the upper motor neuron. The concussion obtained by the blow is conducted along bone to muscle. Muscle spindles are stimulated, and in this manner independent stretch reflexes are produced in these muscles. This mechanism is responsible for the phenomenon of multiple stretch reflexes. The thorax and pelvis play important roles in the contralateral responses by transmitting these mechanical events across the midline. (Henry FordHosp Med J 1986;34:31-6) ontraction of muscles remote from the site of f)ercussion is Head and neck Cencountered in patients with brisk stretch reflexes.
  • Spinal Reflexes Marte Rydland a Reflex Is a Protective Response to Stimulus That Does Not Require Conciousness Reflexes

    Spinal Reflexes Marte Rydland a Reflex Is a Protective Response to Stimulus That Does Not Require Conciousness Reflexes

    Spinal reflexes Marte Rydland A reflex is a protective response to stimulus that does not require conciousness Reflexes Elements of a reflex arc: 1. Receptor 2. Afferent pathway 3. Integration center 4. Efferent pathway 5. Effector Types of reflexes 1. Stretch reflex → Protects from overstretching 2. Golgi tendon reflex → Protects from over contracting 3. Withdrawal reflex → Protects from potentially harmful stimuli Muscle fibers Types of muscle fibers Extrafusal fibers Intrafusal fibers ▪ Outer layer ▪ Encapsulated in sheaths to form ▪ Provide the force for muscle muscle spindle contraction ▪ Innervated by ɣ-motoneurons ▪ Most of skeletal muscle ▪ Smaller than extrafusal fibers ▪ Innervated by ⍺-motoneurons ▪ Too small to generate force ▪ Attach to tendons ▪ Sensory receptors: Detect the stretch of a muscle Intrafusal fibers – Muscle spindle Nuclear bag fibers Nuclear chain fibers • Have nuclei collected in a "bag" • Have nuclei arranged in series region • Are more numerous than nuclear • Onset of stretch bag fibers • Dynamic changes = LENTGH & • Sustained stretch VELOCITY • Static changes = LENGTH • Annulospiraling endings • Flower spray endings • Innervated by group Ia afferents • Innervated by group Ia + II SLOW afferents RAPID RAPID Renshaw inhibition • Inhibitory interneurons • Between LMN/AMN’s • Negative feedback loop • Removes “noise” • Prevents hyperactive muscle contraction How to move a limb? • Antagonizing muscles must do the opposite • Flexors vs. extensors • Reciprocal innervation • Inhibiting interneurons 1. Stretch reflex (myotatic reflex) Stimulus: stretching of the muscle 1. Intrafusal fiber 2. Type Ia sensory fiber (afferent nerve) 3. Monosynaptic 4. α motor neurons (efferent nerve) 5. Extrafusal muscle fibers = Agonist muscle contracts = Antagonist relaxes Knee jerk reflex 2. Golgi tendon reflex (inverse stretch) Stimulus: contraction of the muscle 1.
  • The Plantar Reflex

    The Plantar Reflex

    THE PLANTAR REFLEX a historical, clinical and electromyographic study From the Department of Neurology, Academic Hospital 'Dijkzigt', Rotterdam, The Netherlands THE PLANTAR REFLEX A HISTORICAL, CLINICAL AND ELECTROMYOGRAPHIC STUDY PROEFSCHRIFT TER VERKRIJGING VAN DE GRAAD VAN DOCTOR IN DE GENEESKUNDE AAN DE ERASMUS UNIVERSITEIT TE ROTTERDAM OP GEZAG VAN DE RECTOR MAGNIFICUS PROF. DR. B. LEIJNSE EN VOLGENS BESLU!T VAN HET COLLEGE VAN DEKANEN. DE OPENBARE VERDED!GING ZAL PLAATS VINDEN OP WOENSDAG 16 NOVEMBER 1977 DES NAMIDDAGS TE 4.15 UUR PREC!ES DOOR JAN VAN GIJN GEBOREN TE GELDERMALSEN 1977 KRIPS REPRO - MEPPEL PROMOTOR: DR. H. VAN CREVEL CO-PROMOTOR: PROF. DR. A. STAAL CO-REFERENTEN: PROF. DR. H. G. ]. M. KUYPERS PROF. DR. P. E. VOORHOEVE Aan mijn ouders Aan Carien, Maarten en Willem CONTENTS page GENERAL INTRODUCTION 15 CHAPTER I HISTORY OF THE PLANTAR REFLEX AS A CLINICAL SIGN DISCOVERY - the plantar reflex before Babinski 19 - the toe phenomenon . 21 - Joseph Babinski and his work 24 ACCEPTANCE - the pyramidal syndrome before the toe reflex 26 - confirmation . 26 - a curious eponym in Holland 28 - false positive findings? 29 - false negative findings 29 FLEXION AND EXTENSION SYNERGIES - the Babinski sign as part of a flexion synergy . 31 - opposition from Babinski and others . 33 - ipsilateral limb extension with downgoing toes versus the normal plantar response . 36 - crossed toe responses . 36 - tonic plantar flexion of the toes in hemiplegia 37 RIVAL SIGNS - confusion . 39 - different sites of excitation 39 - stretch reflexes of the toe muscles 41 - spontaneous or associated dorsiflexion of the great toe 42 - effects other than in the toes after plantar stimulation 42 THE PLANTAR RESPONSE IN INFANTS - contradictory findings 43 - the grasp reflex of the foot .