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Chapter 13 Nervios The Espinales Spinal Cord, 3791and SpinalBiol Nerves, JA Cardé, PhD Spinal Reflexes Lecture Presentation by Lee Ann Frederick University of Texas at Arlington © 2015 Pearson Education, Inc. Introducción a Nervios y Reflejos Espinales • Objetivos • Describir los componentes principales de un nervio espinal • Relacionar los patrones de distribución con las regiones que inervan • Introducir los patrones principales de piscinas neuronales • Describir los pasos y la clasificación de reflejos © 2015 Pearson Education, Inc. Introducción a Nervios y Reflejos Espinales • Reflejos espinales • Respuestas nerviosas rápidas, automáticas activadas por un estímulo específico • Controlados por el cordón espinal solamente, sin intervención del cerebro © 2015 Pearson Education, Inc. Figure 13-1 An Overview of Chapters 13 and 14. CHAPTER 14: The Brain Sensory receptors Sensory input over cranial nerves Reflex centers in brain Motor output over cranial nerves Effectors Muscles CHAPTER 13: The Spinal Cord Glands Sensory receptors Sensory input over spinal nerves Reflex centers in spinal cord Motor output over spinal nerves Adipose tissue © 2015 Pearson Education, Inc. 13-2 Cordón Espinal • Anatomía Gruesa • • • • 18 pulgadas (45 cm) ½ pulgada (14 mm) Termina entre L1 y L2 Simetría bilateral • Zurcos dividen el cordón en lados derecho e izq • Posterior mediano zurco – posterior • Anterior mediana fisura – mas profundo anterior © 2015 Pearson Education, Inc. 13-2 Cordón espinal • EL nervio espinal • A cada lado de la espina • Donde se unen las raíces: dorsal y ventral • Mixtos • Transportan tanto fibras aferentes como eferentes © 2015 Pearson Education, Inc. Figure 13-3a The Spinal Cord and Spinal Meninges. White matter Ventral rootlets of spinal nerve Gray matter Dorsal root ganglion Ventral root Spinal nerve Dorsal root Dorsal rootlets of spinal nerve Meninges Pia mater Arachnoid mater Dura mater a A posterior view of the spinal cord, showing the meningeal layers, superficial landmarks, and distribution of gray matter and white matter © 2015 Pearson Education, Inc. Figure 13-3b The Spinal Cord and Spinal Meninges. Meninges ANTERIOR Subarachnoid space Dura mater Arachnoid mater Pia mater Vertebral body Rami communicantes Autonomic (sympathetic) ganglion Ventral root of spinal nerve Ventral ramus Dorsal ramus Spinal cord Adipose tissue in epidural space Denticulate Dorsal root ganglion ligament POSTERIOR b A sectional view through the spinal cord and meninges, showing the relationship of the meninges, spinal cord, and spinal nerves © 2015 Pearson Education, Inc. 13-2 Cordón Espinal • Meninges • Membranas aislantes para el cordón • Funciones: • Protección • Vascularización • Conectan con las craneales • Meningitis • Inflamación por infección Viral o bacteriana © 2015 Pearson Education, Inc. 13-2 Cordon Esponal • Tres meninges 1. Dura mater • externa 2. Aracnoide mater • intermedia 3. Pia mater • interna © 2015 Pearson Education, Inc. 13-2 Cordón espinal • La Dura Mater • Fuerte firbrosa • Cranealmente • Se funde con el periosto occipital • Contínua con la craneal • Caudalmente • Se convierte en fibras • Se une en el filo terminal con el ligamento coccígeo • Espacio epidural • Entre paredes del canal y la dura madre • Anestesia epidural © 2015 Pearson Education, Inc. 13-2 Cordón Espinal • Aracnoide • Recubierta por membrana Aracnoidea • Epitelio escamoso simple • Espacio • Subdural • Entre aracnoide y dura madre • Subaracnoideo • Entre aracnoide y pia madre • Circulación del (CSF) • Líquido Cerebrospinal (CSF) • Gases, nutrientes y desechos s • Punción Lumbar © 2015 Pearson Education, Inc. 13-2 Cordon Espinal • Pia Mater • Interna • Colágeno y elastina • Pegada al cerebro, • análoga a serosa parietal o visceral? © 2015 Pearson Education, Inc. Figure 13-4 The Spinal Cord and Associated Structures. Spinal cord Anterior median fissure Pia mater Denticulate ligaments Dorsal root Ventral root, formed by several “rootlets” from one cervical segment Arachnoid mater (reflected) Dura mater (reflected) Spinal blood vessel © 2015 Pearson Education, Inc. Figure 13-5a The Sectional Organization of the Spinal Cord (Part 1 of 2). Posterior white column Posterior gray horn Dorsal root ganglion Lateral white column Lateral gray horn Anterior gray horn Anterior white column a The left half of this sectional view shows important anatomical landmarks, including the three columns of white matter. The right half indicates the functional organization of the nuclei in the anterior, lateral, and posterior gray horns. © 2015 Pearson Education, Inc. Figure 13-5a The Sectional Organization of the Spinal Cord (Part 2 of 2). Posterior median sulcus Posterior gray commissure Functional Organization of Gray Matter The cell bodies of neurons in the gray matter of the spinal cord are organized into functional groups called nuclei. Somatic Sensory nuclei Visceral Visceral Motor nuclei Somatic Ventral root Anterior gray commissure Anterior white commissure Anterior median fissure a The left half of this sectional view shows important anatomical landmarks, including the three columns of white matter. The right half indicates the functional organization of the nuclei in the anterior, lateral, and posterior gray horns. © 2015 Pearson Education, Inc. 13-4 Nervios Espinales y Plexos • Anatomía de Nervios Espinales • Cada segmento del cordón espinal • Esta conectado a un par de nervios • Cada Nervio espinal: • Esta rodeado por tres capas de tejido conectivo • Suplen vascularización © 2015 Pearson Education, Inc. 13-4 Nervios Espinales y Plexos • Tres capas de tejido conectivo que rodean cada nervio 1. Epineuro • Externa • Densa red de fibras de colágeno 2. Perineuro • Intermedia • Divide los nervios en fascículos 3. Endoneuro • Interna • Rodea axones individuales © 2015 Pearson Education, Inc. Figure 13-6a A Peripheral Nerve. Blood vessels Connective Tissue Layers Epineurium covering peripheral nerve Perineurium (around one fascicle) Endoneurium Schwann cell Myelinated axon Fascicle a A typical peripheral nerve and its connective tissue wrappings © 2015 Pearson Education, Inc. 13-4 Nervios Espinales y Plexos • Nervios Periferales • Salen por forámenes intervertebrales y se ramifican • Ramo gris • no mielina, retorno de ganglio simpático • Ramos blanco, dorsal y ventral • Sensoriales y Motores • Blanco- hacia el ganglio simpático • Dorsal – somático y viscerales, espalda • Ventral – extremidades y ventrolateral © 2015 Pearson Education, Inc. Figure 13-8 Peripheral Distribution of Spinal Nerves (Part 2 of 2). To skeletal muscles of back Postganglionic fibers to smooth muscles, glands, etc., of back 2 The spinal nerve forms just lateral to the intervertebral foramen, where the dorsal and ventral roots unite. 3 Dorsal root Dorsal root ganglion The dorsal ramus contains somatic motor and visceral motor fibers that innervate the skin and skeletal muscles of the back. 4 The axons in the relatively large ventral ramus supply the ventrolateral body surface, structures in the body wall, and the limbs. 1 The ventral root of each spinal nerve contains the axons of somatic motor and visceral motor neurons. Visceral motor nuclei To skeletal muscles of body wall, limbs Somatic motor nuclei Rami communicantes KEY = Somatic motor commands = Visceral motor commands Postganglionic fibers to smooth muscles, glands, visceral organs in thoracic cavity Preganglionic fibers to sympathetic ganglia innervating abdominopelvic viscera © 2015 Pearson Education, Inc. Sympathetic ganglion 7 Postganglionic fibers to smooth muscles, and glands of body wall, limbs 5 The white ramus communicans is the first branch from the spinal nerve and carries visceral motor fibers to a nearby sympathetic ganglion. Because these preganglionic axons are myelinated, this branch has a light color and is therefore known as the white ramus. White rami are only found between T1 and L2. A sympathetic nerve contains preganglionic and postganglionic fibers innervating structures in the thoracic cavity. 1 6 The gray ramus communicans contains preganglionic fibers that innervate glands and smooth muscles in the body wall or limbs. These fibers are unmyelinated and have a dark gray color. Gray rami are associated with each spinal nerve. Figure 13-8 Peripheral Distribution of Spinal Nerves (Part 1 of 2). From interoceptors of back 4 From exteroceptors, proprioceptors of back The dorsal root of each spinal nerve carriers sensory information to the spinal cord. 3 The dorsal ramus carries sensory information from the skin and skeletal muscles of the back. Somatic sensory nuclei 2 The ventral ramus carries sensory information from the ventrolateral body surface, structures in the body, wall, and the limbs. Dorsal root ganglion From exteroceptors, proprioceptors of body wall, limbs From interoceptors of body wall, limbs Rami communicantes Ventral root KEY = Somatic sensations = Visceral sensations © 2015 Pearson Education, Inc. Visceral sensory nuclei 1 The sympathetic nerve carriers sensory information from the visceral organs. From interceptors of visceral organs Figure 13-7 Dermatomes. NV C2–C3 C2 C3 C3 C4 T2 C6 L1 L2 C8 T1 C7 L3 L4 KEY L5 Spinal cord regions C5 T1 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 S2 T2 T3 T4 T5 T6 T7 T8 T9 T10 T11 T12 L1 L2 L 4 L3 L5 C4 C5 T2 C6 S4S3 L1 S5 S1 L5 L2 S2 L3 = Thoracic S1 = Sacral L4 ANTERIOR © 2015 Pearson Education, Inc. T1 C7 = Cervical = Lumbar Dermatomas Regiones en la piel, bilaterales Vigiladas por pares específicos de nervios espinales C8 Neuropatia periferal Perdida regional de funciones sensoriales o motoras Debido a compresión o traumas POSTERIOR 13-4 Nervios Espinales y Plexos • Plexos • Red compleja de fibras nerviosas entrelazadas • Controla musculos esqueletales en el cuello y extremidades • Principalmente fibras de la rama ventral • Los cuatro plexos mayores ventrales 1. 2. 3. 4. Cervical Braquial Lumbar Sacral © 2015 Pearson Education, Inc. Figure 13-9 Peripheral Nerves and Nerve Plexuses (Part 1 of 2). C1-C5 Cervical plexus Brachial plexus C5-T1 C1 C2 C3 C4 C5 C6 C7 C8 T1 T2 T3 T4 T5 T6 T7 Supraclavicular nerve Phrenic nerve Axillary nerve T8 Musculocutaneous nerve T9 Thoracic nerves T10 T11 © 2015 Pearson Education, Inc. Lesser occipital nerve Great auricular nerve Transverse cervical nerve Figure 13-9 Peripheral Nerves and Nerve Plexuses (Part 2 of 2). T12 T12-L4 Lumbar plexus L1 Radial nerve L2 Ulnar nerve L3 Median nerve L4 Sacral plexus L4-S4 L5 S1 S2 S3 S4 S5 Co1 Iliohypogastric nerve Ilioinguinal nerve Lateral femoral cutaneous nerve Genitofemoral nerve Femoral nerve Obturator nerve Superior Inferior Gluteal nerves Pudendal nerve Saphenous nerve Sciatic nerve © 2015 Pearson Education, Inc. 13-4 Nervios Espinales y Plexos • Cervical • Incluye nervios espinales C1–C5 • Inerva cuello, cavidad toracica y diafragma • Nervio principal • Frénico (controla el diafragma) © 2015 Pearson Education, Inc. Figure 13-10 The Cervical Plexus (Part 1 of 2). Cranial Nerves Accessory nerve (N XII) Hypoglossal nerve (N XII) Nerve Roots of Cervical Plexus C1 C2 C3 C4 C5 Clavicle © 2015 Pearson Education, Inc. Figure 13-10 The Cervical Plexus (Part 2 of 2). © 2015 Pearson Education, Inc. Figure 13-10 The Cervical Plexus (Part 2 of 2). © 2015 Pearson Education, Inc. 13-4 Nervios Espinales y Plexos • Braquial • Incluye nervios espinal C5–T1 • Cintura escapular y extremidades superiores • Principales • • • • • Musculocutáneo Mediano Ulnar Axillar Radial © 2015 Pearson Education, Inc. Figure 13-11a The Brachial Plexus. © 2015 Pearson Education, Inc. Figure 13-11a The Brachial Plexus. © 2015 Pearson Education, Inc. Figure 13-11b The Brachial Plexus. © 2015 Pearson Education, Inc. 13-4 Nervios Espinales y Plexos • Lumbar • Incluye nervios espinales T12–L4 • Principales • Genitofemoral • Femoral © 2015 Pearson Education, Inc. Figure 13-12a The Lumbar and Sacral Plexuses. © 2015 Pearson Education, Inc. Figure 13-12a The Lumbar and Sacral Plexuses. © 2015 Pearson Education, Inc. 13-4 Nervios Espinales y Plexos • Sacral • Incluye nervios espinales L4–S4 • Principales • Pudendal • Ciático 1. 2. © 2015 Pearson Education, Inc. Fibular Tibial Figure 13-12b The Lumbar and Sacral Plexuses. Nerve Roots of Sacral Plexus Lumbosacral trunk Sacral Plexus Spinal Segments L4 Nerve and Distribution Superior Gluteal L4–S2 L4–S2 S1 Gluteus maximus muscle S2 Sacrum Skin over perineum and posterior thigh and leg Semimembranosus, semitendinosus, and adductor magnus muscles; branches into tibial and fibular nerves Pudendal S2–S4 S3 S4 Sciatic L4–S3 L5 Inferior Gluteal Posterior Femoral Cutaneous S1–S3 L5 Gluteus minimus, gluteus medius, and tensor fasciae latae muscles The sacral plexus is formed by a branch from L4 and ventral rami of L5–S4. S5 Co1 Muscles of the perineum; skin over external genitalia, bulbospongiosus and ischiocavernosus muscles b Sacral plexus, anterior view © 2015 Pearson Education, Inc. Figure 13-12c The Lumbar and Sacral Plexuses. Iliohypogastric nerve Ilioinguinal nerve Genitofemoral nerve Lateral femoral cutaneous nerve Femoral nerve Obturator nerve Superior gluteal nerve Inferior gluteal nerve Pudendal nerve Posterior femoral cutaneous nerve (cut) Sciatic nerve Saphenous nerve Common fibular nerve Superficial fibular nerve Deep fibular nerve c Nerves of the lumbar and sacral plexuses, anterior view © 2015 Pearson Education, Inc. Figure 13-12d The Lumbar and Sacral Plexuses. Superior gluteal nerve Inferior gluteal nerve Pudendal nerve Posterior femoral cutaneous nerve Sciatic nerve Tibial nerve Common fibular nerve Sural nerve d Nerves of the sacral plexus, posterior view © 2015 Pearson Education, Inc. 13-5 Piscinas Neuronales (Grupos) • Organizacion funcional • Sensoriales • 10 millones • Llevan información hacia el SNC • Motoras • Medio millón • Llevan informacion, comandos a efectores periferales • Interneuronas • 20 billones • Funciones de alto nivel © 2015 Pearson Education, Inc. 13-5 Piscinas Neuronales • Cinco patrones de Circuitos Neuronales 1. Divergencia • Distribuyen información 2. Convergencia • Recogen información 3. Procesamiento en serie • Mueve informacion en una linea 4. Procesamiento paralelo • Mueve informacion por varias rutas simultáneamente 5. Reverberacion • Mecanismo de retroalimentacion positiva © 2015 Pearson Education, Inc. Figure 13-13d 13-13a Neural Circuits: The Organization of Neuronal Pools. a Divergence A mechanism for spreading stimulation to multiple neurons or neuronal pools in the CNS © 2015 Pearson Education, Inc. Figure 13-13b Neural Circuits: The Organization of Neuronal Pools. b Convergence A mechanism for providing input to a single neuron from multiple sources © 2015 Pearson Education, Inc. Figure 13-13c Neural Circuits: The Organization of Neuronal Pools. c Serial processing A mechanism in which neurons or pools work sequentially © 2015 Pearson Education, Inc. Figure 13-13d Neural Circuits: The Organization of Neuronal Pools. d Parallel processing A mechanism in which neurons or pools process the same information simultaneously © 2015 Pearson Education, Inc. Figure 13-13e Neural Circuits: The Organization of Neuronal Pools. e Reverberation A positive feedback mechanism © 2015 Pearson Education, Inc. 13-6 Reflejos • Reflejos • Respuestas automáticas, rápidas, coordinadas aun estímulo, en el cordón espinal • Interconecciones de neuronas sensoriales interneuronas y motoras © 2015 Pearson Education, Inc. 13-6 Reflejo • Respuestas rápidas, y automáticas a un estímulo específico • 1:1 - Un reflejo produce una respuesta motora • Arco reflejo • La ruta por la que viaja de un reflejo simple • Receptor efector • Generalmente retroalimentación negativa, se oponen al estímulo © 2015 Pearson Education, Inc. 13-6 Reflejos • Cinco pasos del reflejo • Llega el estímulo, activa el receptor • Estímulo cambio químico o físico • Activación de neurona sensorial • Depolarización de grado • Procesamiento en neurona postsináptica • Liberación de NTs de la presináptica • Activación de la neurona motora • Potencial de acción • Respuesta de efector periferal • Activada por NTs © 2015 Pearson Education, Inc. Figure 13-14 Spinal Reflexes (Part 1 of 4). 1 2 Arrival of stimulus and activation of receptor Dorsal root Activation of a sensory neuron Sensation relayed to the brain by axon collaterals Spinal cord 3 Information processing in the CNS REFLEX ARC Receptor Stimulus 5 Response by a peripheral effector Effector 4 Ventral root Activation of a motor neuron © 2015 Pearson Education, Inc. KEY Sensory neuron (stimulated) Excitatory interneuron Motor neuron (stimulated) 13-6 Reflejos Clasificación • Clasificación de los reflejos de acuerdo a: 1. 2. 3. 4. Desarrollo temprano Respuesta motora Complejidad del circuito Lugar de procesamiento © 2015 Pearson Education, Inc. 13-6 Reflejos Clasificación • Desarrollo • Innatos • Desarrollados antes de nacer • Adquiridos • Patrones aprendidos • Rapidos automáticos • Respuesta motora • En que consiste la respuesta, en activar que cosa: • Somáticos • Control involuntario del sistema nervioso • Piel, mucosas, tendones, estiramientos, patelar • Viscerales (autonómicos) • Controla otros sistemas fuera del muscular © 2015 Pearson Education, Inc. 13-6 Reflejos Clasificación • Complejidad del circuito neural • Monosinápticos • Neurona sensorial Neurona motora • Polisinápticos • Al menos una interneurona entre la sensorial y la motora • Lugar de procesamiento • Espinales • Se procesa en el cordón espinal • Craneales • Se procesa en el cerebro © 2015 Pearson Education, Inc. Figure 13-15 The Classification of Reflexes. Reflexes can be classified by development Innate Reflexes • Genetically determined Acquired Reflexes • Learned response complexity of circuit processing site Somatic Reflexes Monosynaptic Spinal Reflexes • Control skeletal muscle contractions • Include superficial and stretch reflexes Visceral (Autonomic) Reflexes • Control actions of smooth and cardiac muscles, glands, and adipose tissue © 2015 Pearson Education, Inc. • One synapse • Processing in the spinal cord Polysynaptic • Multiple synapses (two to several hundred) Cranial Reflexes • Processing in the brain 13-7 Espinales • Aumentan en nivel de complejidad • Monosinapticos • Polisinapticos • Intersegmentarios • Varios segementos • Respuestas que varian en complejidad © 2015 Pearson Education, Inc. 13-7 Espinales • Monosinapticos • • • • De Estiramientos De sensorial a motora Poco retraso Receptor : huso muscular © 2015 Pearson Education, Inc. Figure 13-14 Spinal Reflexes (Part 2 of 4). Stretch Receptor (muscle spindle) Spinal cord REFLEX ARC Stimulus Effector KEY Response © 2015 Pearson Education, Inc. Sensory neuron (stimulated) Motor neuron (stimulated) Figure 13-16 A Muscle Spindle. Gamma efferent from CNS Extrafusal fiber To CNS Sensory region Intrafusal fiber Muscle spindle Gamma efferent from CNS © 2015 Pearson Education, Inc. 13-7 Espinales • Posturales • Estiramientos • Postura erecta • Músculos que se estiran reaccionan contrayéndose y se mantiene un balance • Tensión acumulada, fatiga muscular © 2015 Pearson Education, Inc. 13-7 Espinales • Polisinapticos • Complicados • Interneuronas • Balance entre EPSP e IPSP © 2015 Pearson Education, Inc. 13-7 Espinal • De Retirada • Alejar una parte del cuerpo del lugar del estimulo • Flexor • Retirar la mano de algo caliente • Fuerza y duración de respuesta • Depende de intensidad del estimulo Ipsilaterales vs Contralateral © 2015 Pearson Education, Inc. Figure 13-14 Spinal Reflexes (Part 3 of 4). Distribution within gray horns to other segments of the spinal cord Painful stimulus Flexors stimulated Extensors inhibited Ipsilaterales Ocurren en el mismo lado donde ocurre el estimulo Estiramiento, tendones, de retirada © 2015 Pearson Education, Inc. Figure 13-14 Spinal Reflexes (Part 4 of 4). Reflejo extensor cruzado Contralateral En el lado opuesto al estímulo Simultaneo coordinado con flexor Flexor recoje la pierna Extensor estira la otra pierna Para sostener el peso To motor neurons in other segments of the spinal cord Extensors inhibited Flexors stimulated Extensors stimulated Flexors inhibited KEY Sensory neuron (stimulated) Motor neuron (inhibited) Excitatory interneuron Inhibitory interneuron Motor neuron (stimulated) © 2015 Pearson Education, Inc. Painful stimulus 13-8 El Cerebro puede alterar los reflejos espinales • Babinski • Normal en infante • Anormal en adulto • Puede indicar daño al SNC en adultos © 2015 Pearson Education, Inc. Figure 13-17a The Babinski Reflexes. The plantar reflex (negative Babinski reflex), a curling of the toes, normal in healthy adults. © 2015 Pearson Education, Inc. Figure 13-17b The Babinski Reflexes. The Babinski sign (positive Babinski reflex) occurs in the absence of descending inhibition. It is normal in infants, but pathological in adults. © 2015 Pearson Education, Inc.