(Corticobulbar) Tract

Total Page：16

File Type：pdf, Size：1020Kb

Cor$cospinal (cor$cobulbar) Tract 6/18/12 1. Appreciate the functions of the corticospinal & corticobulbar tracts. 2. Distinguish corticospinal and corticobulbar tracts. Theodore Tzavaras MD2015 3. Identify the locations of both Laurie L. Wellman Ph.D. tracts through the forebrain, Eastern Virginia Medical School brainstem and spinal cord. 4. Identify the level of decussation of the corticospinal tract, and it’s clinical importance. Dr. Craig Goodmurphy Anatomy Guy Pathway Overview Pathway Overview Corticospinal Corticobulbar ² Begin in primary motor cortex. ² Begin in primary motor cortex. ² Upper ² Travel through the posterior limb Travel through the posterior limb Upper of the internal capsule (somatotopic). Motor of the internal capsule (somatotopic). Motor ² Descend through the middle 3/5 of Neuron ² Descend through the middle 3/5 of the crus cerebri (somatotopic). the crus cerebri (somatotopic). Neuron ² Travel through the brainstem as ² Travel through the brainstem and the descending pyramidal system. synapse on brainstem nuclei. Crosses Lower ² Decussate at the caudal medulla in Midline ² α-Motor neurons project along the pyramidal decussation. cranial nerves for facial movements Motor ² Descend in the spinal cord as the and voice production. Neuron corticospinal tract Lower ² All cranial nerve nuclei receive ² Synapse on α-motor neurons Motor bilateral UMN input* ² Exit spinal cord in ventral rami Neuron *Part of CN VI is the exception AnatomyGuy.com 1 Cor$cospinal (cor$cobulbar) Tract 6/18/12 Overview Corticospinal ² Primary motor cortex Don’t ü ² Try to learn all the details on your first Posterior limb of the internal pass. capsule (somatotopic). Do ü Try to sketch out each brain, ² Middle 3/5 of the crus cerebri brainstem, and cord level we showed (somatotopic). today and indicate on those sketches ² Brainstem: descending pyramidal the corticospinal tract location. Don’t ü Worry if the tracts don’t make perfect system. sense the first time around. ² Caudal medulla: Pyramidal Do ü Once you have the tract locations decussation. down and the decussation makes ² Spinal cord: corticospinal tract sense, add the somatotopic “fluff” ² Synapse on α-motor neurons in details. ventral horn ² Exit spinal cord in ventral rami Midline AnatomyGuy.com 2 .

Copy Link

Recommended publications

Spinal Tracts.Pdf
Spinal Tracts Andreas Talgø Lie Illustrations by: Peder Olai Skjeflo Holman Previous material: Maja Solbakken Definitions to bring home Nerve Ganglion Neuron Nucleus Tract Collection neurons Collection of nerve A single cell Collection of Collection of axons that transmits cell bodies in the transmitting nerve cell bodies in traveling up or sensation or motor PNS, typically linked electrical impluses. the CNS, typically down the spinal impulses depending by synapses. linked by synapses. cord, depending on the function and Location: both on function destination. Location: PNS Location: CNS and destination. Location: PNS Location: CNS - does it matter? Tract - highway to pass anatomy exam? • Highway = Tract • Lane = Neuron • Car = Signal Slow... Fast!! Just to make sure... • Ipsilateral or contralateral • Ventral = anterior • Dorsal = posterior High yield points to understand • What does the tract transmit - Motor or sensory? If sensory: which sensation? • Where does the neurones synapse - 1.st, 2nd and 3rd order neron? Which ganglion/nuclei? • Where there are decussations - If there are any decussations at all? ASCENDING / SENSORY TRACTS Sensations * Temperature NOT transmitted by the tracts: * Pressure * Visualization * Pain * Audition * Fine touch * Olfaction * Crude touch * Gustation * Proprioception * Vibration Sensations Precise sensation Primitive sensation Fine touch Crude touch Pressure Pain Vibration Temperature Proprioception Other: sexual, itching, tickling Ascending tracts / Sensory tracts Dorsal coulmn Lat. Spinothalamic Ant.
[Show full text]
L4-Physiology of Motor Tracts.Pdf
: chapter 55 page 667 Objectives (1) Describe the upper and lower motor neurons. (2) Understand the pathway of Pyramidal tracts (Corticospinal & corticobulbar tracts). (3) Understand the lateral and ventral corticospinal tracts. (4) Explain functional role of corticospinal & corticobulbar tracts. (5) Describe the Extrapyramidal tracts as Rubrospinal, Vestibulospinal, Reticulospinal and Tectspinal Tracts. The name of the tract indicate its pathway, for example Corticobulbar : Terms: - cortico: cerebral cortex. Decustation: crossing. - Bulbar: brainstem. Ipsilateral : same side. *So it starts at cerebral cortex and Contralateral: opposite side. terminate at the brainstem. CNS influence the activity of skeletal muscle through two set of neurons : 1- Upper motor neurons (UMN) 2- lower motor neuron (LMN) They are neurons of motor cortex & their axons that pass to brain stem and They are Spinal motor neurons in the spinal spinal cord to activate: cord & cranial motor neurons in the brain • cranial motor neurons (in brainstem) stem which innervate muscles directly. • spinal motor neurons (in spinal cord) - These are the only neurons that innervate - Upper motor neurons (UMN) are the skeletal muscle fibers, they function as responsible for conveying impulses for the final common pathway, the final link voluntary motor activity through between the CNS and skeletal muscles. descending motor pathways that make up by the upper motor neurons. Lower motor neurons are classified based on the type of muscle fiber the innervate: There are two UMN Systems through which 1- alpha motor neurons (UMN) control (LMN): 2- gamma motor neurons 1- Pyramidal system (corticospinal tracts ). 2- Extrapyramidal system The activity of the lower motor neuron (LMN, spinal or cranial) is influenced by: 1.
[Show full text]
Identification of the Corticobulbar Tracts of the Tongue and Face Using Deterministic and Probabilistic DTI Fiber Tracking in Pa
Published August 6, 2015 as 10.3174/ajnr.A4430 ORIGINAL RESEARCH ADULT BRAIN Identification of the Corticobulbar Tracts of the Tongue and Face Using Deterministic and Probabilistic DTI Fiber Tracking in Patients with Brain Tumor M. Jenabi, X K.K. Peck, X R.J. Young, N. Brennan, and X A.I. Holodny ABSTRACT BACKGROUND AND PURPOSE: The corticobulbar tract of the face and tongue, a critical white matter tract connecting the primary motor cortex and the pons, is rarely detected by deterministic DTI fiber tractography. Detection becomes even more difficult in the presence of a tumor. The purpose of this study was to compare identification of the corticobulbar tract by using deterministic and probabilistic tractography in patients with brain tumor. MATERIALS AND METHODS: Fifty patients with brain tumor who underwent DTI were studied. Deterministic tractography was per- formed by using the fiber assignment by continuous tractography algorithm. Probabilistic tractography was performed by using a Monte Carlo simulation method. ROIs were drawn of the face and tongue motor homunculi and the pons in both hemispheres. RESULTS: In all subjects, fiber assignment by continuous tractography was ineffectual in visualizing the entire course of the corticobulbar tract between the face and tongue motor cortices and the pons on either side. However, probabilistic tractography successfully visualized the corticobulbar tract from the face and tongue motor cortices in all patients on both sides. No significant difference (P Ͻ .08) was found between both sides in terms of the number of voxels or degree of connectivity. The fractional anisotropy of both the face and tongue was significantly lower on the tumor side (P Ͻ .03).
[Show full text]
Do the Corticospinal and Corticobulbar Tracts Mediate Functions in the Human Newborn?
LE JOURNAL CANAD1EN DES SCIENCES NEUROLOGIQUES HYPOTHESIS Do the Corticospinal and Corticobulbar Tracts Mediate Functions in the Human Newborn? Harvey B. Sarnat ABSTRACT: Unlike the numerous dispersed bulbospinal pathways that are already well myelinated at term, the more compact corticospinal and corticobulbar tracts are only beginning their myelination cycle in late gestation and do not complete it until two years of age. During this same period, these pathways also develop extensive ramification of ter minal axonal segments, growth of collateral axons, and proliferation of synapses. Despite their immaturity in the full- term human newborn, several proposed functions may be attributed to the descending pathways from the neonatal cerebral cortex: a) a contribution to the differential development of passive muscle tone and resting postures; in general they function as an antagonist to the "subcorticospinal pathways" in mediating proximal flexion and distal extension, except for the rubrospinal tract which is probably synergistic with the corticospinal tract; b) enhancement of tactile reflexes originating in the brainstem and spinal cord, including suck and swallow; c) relay of epileptic activity of corti cal origin; d) inhibition of complex stereotyped motor reflexes including many phenomena formerly termed "subtle seizures"; e) a possible influence on muscle maturation, particularly in relaying cerebellar impulses that modify the histochemical differentiation of myofibres. However, the bulbospinal tracts are probably more influential
[Show full text]
Brainstem Dysfunction in Critically Ill Patients
Benghanem et al. Critical Care (2020) 24:5 https://doi.org/10.1186/s13054-019-2718-9 REVIEW Open Access Brainstem dysfunction in critically ill patients Sarah Benghanem1,2 , Aurélien Mazeraud3,4, Eric Azabou5, Vibol Chhor6, Cassia Righy Shinotsuka7,8, Jan Claassen9, Benjamin Rohaut1,9,10† and Tarek Sharshar3,4*† Abstract The brainstem conveys sensory and motor inputs between the spinal cord and the brain, and contains nuclei of the cranial nerves. It controls the sleep-wake cycle and vital functions via the ascending reticular activating system and the autonomic nuclei, respectively. Brainstem dysfunction may lead to sensory and motor deficits, cranial nerve palsies, impairment of consciousness, dysautonomia, and respiratory failure. The brainstem is prone to various primary and secondary insults, resulting in acute or chronic dysfunction. Of particular importance for characterizing brainstem dysfunction and identifying the underlying etiology are a detailed clinical examination, MRI, neurophysiologic tests such as brainstem auditory evoked potentials, and an analysis of the cerebrospinal fluid. Detection of brainstem dysfunction is challenging but of utmost importance in comatose and deeply sedated patients both to guide therapy and to support outcome prediction. In the present review, we summarize the neuroanatomy, clinical syndromes, and diagnostic techniques of critical illness-associated brainstem dysfunction for the critical care setting. Keywords: Brainstem dysfunction, Brain injured patients, Intensive care unit, Sedation, Brainstem
[Show full text]
1 Physiology Week 4 – Reflexes
Physiology week 4 – Reflexes Reflexes Reflex arc Sensory organ Afferent neuron (enters cord via dorsal roots or cranial nerves) One or more synapses Efferent neuron (leaves the cord via ventral roots or cranial nerves) Effector Bell-Magendie law Spinal cord dorsal roots are sensory Spinal cord ventral roots are motor Monosynaptic reflexes Stretch reflex eg. knee jerk, ankle jerk Sense organ (muscle spindle) Ia fibre, afferent neuron (same as efferent nerve supply) One synapse (neurotransmitter is glutamate) Efferent neuron (motor neurone) Effector (muscle) Reciprocal innervation of muscle antagonist Muscle spindle fxn - parallel intrafusal fibres respond to stretch with different dynamic/static responses. Inverse stretch reflex Stretch can increase to a maximum, but once this point is reached, the muscle relaxes (following prolonged stretch or muscle contraction the contracted muscles suddenly relax) Sense organ (golgi apparatus) Afferent neuron (same as efferent nerve supply) One synapses (neurotransmitter is glutamate) Efferent neuron Effector (muscle) Clonus ‘regular rhythmic contraction of a muscle that is subjected to sudden maintained stretch’ Caused by increased gamma efferent discharge in response to hyperactive muscle spindles Polysynaptic reflexes Polysynaptic reflexes branch in a complex fashion One or more interneurons, interposed between the afferent and efferent neurones Number of synapses is variable Withdrawal reflex Sense organ (noxious stimulus skin or subcut) Afferent neuron (same as efferent nerve supply) Multiple synapses (neurotransmitter is glutamate) 1 Efferent neuron Effector (ipsilateral flexor contraction/extensor relaxation + crossed extensor response of opposite limb) Results in withdrawal of limb from stimulus Cross extensor response opposite limb Prepotency of the withdrawal reflex the reflex pre-empts spinal pathways from any other reflex activity occurring at the same time.
[Show full text]
Brainstem Dysfunction in Critically Ill Patients
Benghanem et al. Critical Care (2020) 24:5 https://doi.org/10.1186/s13054-019-2718-9 REVIEW Open Access Brainstem dysfunction in critically ill patients Sarah Benghanem1,2 , Aurélien Mazeraud3,4, Eric Azabou5, Vibol Chhor6, Cassia Righy Shinotsuka7,8, Jan Claassen9, Benjamin Rohaut1,9,10† and Tarek Sharshar3,4*† Abstract The brainstem conveys sensory and motor inputs between the spinal cord and the brain, and contains nuclei of the cranial nerves. It controls the sleep-wake cycle and vital functions via the ascending reticular activating system and the autonomic nuclei, respectively. Brainstem dysfunction may lead to sensory and motor deficits, cranial nerve palsies, impairment of consciousness, dysautonomia, and respiratory failure. The brainstem is prone to various primary and secondary insults, resulting in acute or chronic dysfunction. Of particular importance for characterizing brainstem dysfunction and identifying the underlying etiology are a detailed clinical examination, MRI, neurophysiologic tests such as brainstem auditory evoked potentials, and an analysis of the cerebrospinal fluid. Detection of brainstem dysfunction is challenging but of utmost importance in comatose and deeply sedated patients both to guide therapy and to support outcome prediction. In the present review, we summarize the neuroanatomy, clinical syndromes, and diagnostic techniques of critical illness-associated brainstem dysfunction for the critical care setting. Keywords: Brainstem dysfunction, Brain injured patients, Intensive care unit, Sedation, Brainstem
[Show full text]
Cerebral Cortex
Cerebral Cortex • Research on the structure and function of the brain reveals that there are both specialized and diffuse areas of function • Motor and sensory areas are localized in discrete cortical areas called domains • Many higher mental functions such as memory and language appear to have overlapping domains and are more diffusely located • Broadmann areas are areas of localized function Cerebral Cortex - Generalizations • The cerebral cortex has three types of functional areas – Motor areas / control voluntary motor function – Sensory areas / provide conscious awareness of sensation – Association areas / act mainly to integrate diverse information for purposeful action • Each hemisphere is chiefly concerned with the sensory and motor functions of the opposite (contralateral) side of the body Motor Areas • Cortical areas controlling motor functions lie in the posterior part of the frontal lobes • Motor areas include the primary motor cortex, the premotor cortex, Broca’s area, and the front eye field Primary Motor Cortex • The primary motor cortex is located in the precentral gyrus of the frontal lobe of each hemisphere • Large neurons (pyramidal cells) in these gyri allow us to consciously control the precise or skill voluntary movements of our skeletal muscles Pyramidal cells • These long axons, which project to the spinal cord, form the massive Dendrites voluntary motor tracts called the pyramidal, or corticospinal tracts • All other descending motor tracts issue from brain stem nuclei and consists of chains of two, three, or
[Show full text]
Amyotrophic Lateral Sclerosis (ALS)
Amyotrophic Lateral Sclerosis (ALS) There are multiple motor neuron diseases. Each has its own defining features and many characteristics that are shared by all of them: Degenerative disease of the nervous system Progressive despite treatments and therapies Begins quietly after a period of normal nervous system function ALS is the most common motor neuron disease. One of its defining features is that it is a motor neuron disease that affects both upper and lower motor neurons. Anatomical Involvement ALS is a disease that causes muscle atrophy in the muscles of the extremities, trunk, mouth and face. In some instances mood and memory function are also affected. The disease operates by attacking the motor neurons located in the central nervous system which direct voluntary muscle function. The impulses that control the muscle function originate with the upper motor neurons in the brain and continue along efferent (descending) CNS pathways through the brainstem into the spinal cord. The disease does not affect the sensory or autonomic system because ALS affects only the motor systems. ALS is a disease of both upper and lower motor neurons and is diagnosed in part through the use of NCS/EMG which evaluates lower motor neuron function. All motor neurons are upper motor neurons so long as they are encased in the brain or spinal cord. Once the neuron exits the spinal cord, it operates as a lower motor neuron. 1 Upper Motor Neurons The upper motor neurons are derived from corticospinal and corticobulbar fibers that originate in the brain’s primary motor cortex. They are responsible for carrying impulses for voluntary motor activity from the cerebral cortex to the lower motor neurons.
[Show full text]
Brain Mechanisms of Acoustic Communication in Humans and Nonhuman Primates: an Evolutionary Perspective
BEHAVIORAL AND BRAIN SCIENCES (2014) 37, 529–604 doi:10.1017/S0140525X13003099 Brain mechanisms of acoustic communication in humans and nonhuman primates: An evolutionary perspective Hermann Ackermann Neurophonetics Group, Centre for Neurology – General Neurology, Hertie Institute for Clinical Brain Research, University of Tuebingen, D-72076 Tuebingen, Germany [email protected] www.hih-tuebingen.de/neurophonetik Steffen R. Hage Neurobiology of Vocal Communication Research Group, Werner Reichardt Centre for Integrative Neuroscience, and Institute for Neurobiology, Department of Biology, University of Tuebingen, D-72076 Tuebingen, Germany [email protected] www.vocalcommunication.de Wolfram Ziegler Clinical Neuropsychology Research Group, City Hospital Munich- Bogenhausen, D-80992 Munich, and Institute of Phonetics and Speech Processing, Ludwig-Maximilians-University, D-80799 Munich, Germany. [email protected] www.ekn.mwn.de Abstract: Any account of “what is special about the human brain” (Passingham 2008) must specify the neural basis of our unique ability to produce speech and delineate how these remarkable motor capabilities could have emerged in our hominin ancestors. Clinical data suggest that the basal ganglia provide a platform for the integration of primate-general mechanisms of acoustic communication with the faculty of articulate speech in humans. Furthermore, neurobiological and paleoanthropological data point at a two-stage model of the phylogenetic evolution of this crucial prerequisite of spoken language: (i) monosynaptic reﬁnement of the projections of motor cortex to the brainstem nuclei that steer laryngeal muscles, presumably, as part of a “phylogenetic trend” associated with increasing brain size during hominin evolution; (ii) subsequent vocal-laryngeal elaboration of cortico-basal ganglia circuitries, driven by human-speciﬁc FOXP2 mutations.
[Show full text]
The Neural Basis of Speech and Language
© Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION CHAPTER © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC The NeuralNOT FOR SALE Basis OR DISTRIBUTION of NOT FOR SALE OR DISTRIBUTION Speech and Language 2 © Jones & Bartlett Learning, LLC © Jones & Bartlett Learning, LLC NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION Introduction © Jones & BartlettThis section Learning, gives the LLC reader a brief overview ©of Joneswhat takes & Bartlett place neurally Learning, when LLCa per- son starts a conversation by saying, “Hello. How are you? How was your vacation NOT FOR SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION trip?” to another individual whom the person meets on the street. Simply put, the steps involved would be as follows: 1. Basic vision: seeing a person on the street 2. Visual perception: recognizing the person as someone the speaker knows 3. Cognition:© theJones desire & to Bartlett speak with Learning, this person LLC about a trip that the speaker© Jones may & Bartlett Learning, LLC want to takeNOT in FORthe future SALE OR DISTRIBUTION NOT FOR SALE OR DISTRIBUTION 4. Language: searching for the right sounds, syllables, words, and sentences, all pre- sented in the right order, with meaning properly related to the greeting and the subject matter, to be expressed with a positive attitude © Jones5. Motor & Bartlettprogramming Learning, or planning: LLC readying the speech© mechanism Jones & Bartlettjust prior Learning, to LLC NOT speakingFOR SALE so that OR the DISTRIBUTION production is correct NOT FOR SALE OR DISTRIBUTION 6. Motor production or execution: speaking 7.
[Show full text]
The Effect of Swallowing Treatments on Corticobulbar Excitability: a Review
Journal of Neuroscience Methods 233 (2014) 89–98 Contents lists available at ScienceDirect Journal of Neuroscience Methods jo urnal homepage: www.elsevier.com/locate/jneumeth Basic Neuroscience The effect of swallowing treatments on corticobulbar excitability: A review of transcranial magnetic stimulation induced motor evoked potentials a,b,∗ a,b,c,d a,b Phoebe R. Macrae , Richard D. Jones , Maggie-Lee Huckabee a New Zealand Brain Research Institute, 66 Stewart Street, Christchurch, New Zealand b Department of Communication Disorders, University of Canterbury, Private Bag 4800, Christchurch, New Zealand c Department of Medicine, University of Otago, Private Bag 4710, Christchurch, New Zealand d Department of Medical Physics and Bioengineering, Canterbury District Health Board, Private Bag 4710, Christchurch, New Zealand h i g h l i g h t s • MEPs are used with increasing frequency in swallowing research. • The link between cortical excitability and functional swallowing behaviour is unclear. • Large standard deviations are typical of MEPs recorded from swallowing muscles. • Analysis characteristics need to be clearly deﬁned for comparison between studies. • A review of considerations speciﬁc to swallowing related MEPs is provided. a r t i c l e i n f o a b s t r a c t Article history: Transcranial magnetic stimulation (TMS) has been used extensively as a method of investigating the Received 7 August 2013 corticomotor physiology of many motor tasks, including healthy and disordered swallowing. Changes Received in revised form 7 June 2014 in excitability of cortical projections to various swallowing muscles have been documented in response Accepted 9 June 2014 to treatments with TMS induced motor evoked potentials (MEPs).
[Show full text]