Nervios Espinales Biol 3791 JA Cardé, PhD.

Presentación del tema: "Nervios Espinales Biol 3791 JA Cardé, PhD."— Transcripción de la presentación:

1 Nervios Espinales Biol 3791 JA Cardé, PhD

2 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

3 Introducción a Nervios y Reflejos Espinales
Respuestas nerviosas rápidas, automáticas activadas por un estímulo específico Controlados por el cordón espinal solamente, sin intervención del cerebro

4 Figure 13-1 An Overview of Chapters 13 and 14.
CHAPTER 14: The Brain Sensory input over cranial nerves Motor output over cranial nerves Reflex centers in brain Effectors Sensory receptors Muscles CHAPTER 13: The Spinal Cord Glands Sensory input over spinal nerves Motor output over spinal nerves Reflex centers in spinal cord Sensory receptors Adipose tissue

5 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

6 13-2 Cordón espinal EL nervio espinal A cada lado de la espina Mixtos
Donde se unen las raíces: dorsal y ventral Mixtos Transportan tanto fibras aferentes como eferentes

7 Figure 13-3a The Spinal Cord and Spinal Meninges.
Gray matter White matter Ventral rootlets of spinal nerve Dorsal root ganglion Ventral root Spinal nerve Dorsal root Meninges Dorsal rootlets of spinal nerve 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

8 Figure 13-3b The Spinal Cord and Spinal Meninges.
Dura mater Arachnoid mater ANTERIOR Pia mater Subarachnoid space Vertebral body Autonomic (sympathetic) ganglion Rami communicantes Ventral root of spinal nerve Ventral ramus Dorsal ramus Spinal cord Adipose tissue in epidural space Denticulate ligament Dorsal root ganglion POSTERIOR b A sectional view through the spinal cord and meninges, showing the relationship of the meninges, spinal cord, and spinal nerves

9 13-2 Cordón Espinal Meninges Membranas aislantes para el cordón
Funciones: Protección Vascularización Conectan con las craneales Meningitis Inflamación por infección Viral o bacteriana

10 13-2 Cordon Esponal Tres meninges Dura mater Aracnoide mater Pia mater
externa Aracnoide mater intermedia Pia mater interna

11 13-2 Cordón espinal La Dura Mater Espacio epidural 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

12 13-2 Cordón Espinal Aracnoide Subdural Subaracnoideo
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

13 13-2 Cordon Espinal Pia Mater Interna Colágeno y elastina
Pegada al cerebro, análoga a serosa parietal o visceral?

14 Figure 13-4 The Spinal Cord and Associated Structures.
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

15 of white matter. The right half indicates the
Figure 13-5a The Sectional Organization of the Spinal Cord (Part 1 of 2). Posterior white column Posterior gray horn Lateral white column Lateral gray horn Dorsal root ganglion 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.

16 Functional Organization of Gray Matter
Figure 13-5a The Sectional Organization of the Spinal Cord (Part 2 of 2). Posterior median sulcus Functional Organization of Gray Matter Posterior gray commissure 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.

17 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

18 13-4 Nervios Espinales y Plexos
Tres capas de tejido conectivo que rodean cada nervio Epineuro Externa Densa red de fibras de colágeno Perineuro Intermedia Divide los nervios en fascículos Endoneuro Interna Rodea axones individuales

19 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

20 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

21 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 The dorsal ramus contains somatic motor and visceral motor fibers that innervate the skin and skeletal muscles of the back. Dorsal root ganglion Dorsal root 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 Postganglionic fibers to smooth muscles, and glands of body wall, limbs = Somatic motor commands Sympathetic ganglion = Visceral motor commands 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. Postganglionic fibers to smooth muscles, glands, visceral organs in thoracic cavity 7 A sympathetic nerve contains preganglionic and postganglionic fibers innervating structures in the thoracic cavity. 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. Preganglionic fibers to sympathetic ganglia innervating abdominopelvic viscera 1

22 Figure 13-8 Peripheral Distribution of Spinal Nerves (Part 1 of 2).
From interoceptors of back From exteroceptors, proprioceptors of back 4 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 Visceral sensory nuclei Ventral root KEY = Somatic sensations 1 = Visceral sensations The sympathetic nerve carriers sensory information from the visceral organs. From interceptors of visceral organs

23 Regiones en la piel, bilaterales
Figure 13-7 Dermatomes. N V Dermatomas Regiones en la piel, bilaterales Vigiladas por pares específicos de nervios espinales C2–C3 C2 C3 C3 C4 T2 T2 C4 C5 T3 T1 T4 T2 T5 T3 C5 T6 T4 T7 T5 T8 T6 T9 T2 T2 T7 T10 T8 T11 T9 T12 L1 C6 T10 L2 T11 L4 L3 T1 C6 C7 T12 L5 L1 S4 S3 L2 S2 C8 T1 L3 C8 L1 L1 C7 S5 S1 L5 L4 Neuropatia periferal Perdida regional de funciones sensoriales o motoras Debido a compresión o traumas L2 S2 KEY L5 L3 Spinal cord regions = Cervical = Thoracic S1 = Lumbar = Sacral L4 ANTERIOR POSTERIOR

24 13-4 Nervios Espinales y 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 Cervical Braquial Lumbar Sacral

25 Figure 13-9 Peripheral Nerves and Nerve Plexuses (Part 1 of 2).
C1-C5 C1 Lesser occipital nerve C2 Great auricular nerve Cervical plexus C3 Transverse cervical nerve C4 C5 Supraclavicular nerve C6 Phrenic nerve Brachial plexus C7 C8 T1 T2 T3 C5-T1 Axillary nerve T4 T5 T6 T7 Musculocutaneous nerve T8 T9 Thoracic nerves T10 T11

26 Figure 13-9 Peripheral Nerves and Nerve Plexuses (Part 2 of 2).
T12-L4 L1 Radial nerve Lumbar plexus L2 L2 Ulnar nerve L3 Median nerve L4 L5 S1 Iliohypogastric nerve Sacral plexus S2 S3 L4-S4 S4 Ilioinguinal nerve S5 Co1 Lateral femoral cutaneous nerve Genitofemoral nerve Femoral nerve Obturator nerve Superior Gluteal nerves Inferior Pudendal nerve Saphenous nerve Sciatic nerve

27 13-4 Nervios Espinales y Plexos
Cervical Incluye nervios espinales C1–C5 Inerva cuello, cavidad toracica y diafragma Nervio principal Frénico (controla el diafragma)

28 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

29 Figure 13-10 The Cervical Plexus (Part 2 of 2).

30 Figure 13-10 The Cervical Plexus (Part 2 of 2).

31 13-4 Nervios Espinales y Plexos
Braquial Incluye nervios espinal C5–T1 Cintura escapular y extremidades superiores Principales Musculocutáneo Mediano Ulnar Axillar Radial

32 Figure 13-11a The Brachial Plexus.

33 Figure 13-11a The Brachial Plexus.

34 Figure 13-11b The Brachial Plexus.

35 13-4 Nervios Espinales y Plexos
Lumbar Incluye nervios espinales T12–L4 Principales Genitofemoral Femoral

36 Figure 13-12a The Lumbar and Sacral Plexuses.

37 Figure 13-12a The Lumbar and Sacral Plexuses.

38 13-4 Nervios Espinales y Plexos
Sacral Incluye nervios espinales L4–S4 Principales Pudendal Ciático Fibular Tibial

39 Figure 13-12b The Lumbar and Sacral Plexuses.
Lumbosacral trunk Nerve Roots of Sacral Plexus Sacral Plexus L4 The sacral plexus is formed by a branch from L4 and ventral rami of L5–S4. Spinal Segments Nerve and Distribution Superior Gluteal L5 L4–S2 Gluteus minimus, gluteus medius, and tensor fasciae latae muscles L5 Inferior Gluteal S1 L4–S2 Gluteus maximus muscle S2 Posterior Femoral Cutaneous Sacrum S3 S1–S3 Skin over perineum and posterior thigh and leg S4 Sciatic L4–S3 Semimembranosus, semitendinosus, and adductor magnus muscles; branches into tibial and fibular nerves S5 Pudendal Co1 S2–S4 Muscles of the perineum; skin over external genitalia, bulbospongiosus and ischiocavernosus muscles b Sacral plexus, anterior view

40 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

41 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

42 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

43 13-5 Piscinas Neuronales Cinco patrones de Circuitos Neuronales
Divergencia Distribuyen información Convergencia Recogen información Procesamiento en serie Mueve informacion en una linea Procesamiento paralelo Mueve informacion por varias rutas simultáneamente Reverberacion Mecanismo de retroalimentacion positiva

44 Figure 13-13a Neural Circuits: The Organization of Neuronal Pools.
Figure 13-13d Neural Circuits: The Organization of Neuronal Pools. Figure 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

45 Figure 13-13b Neural Circuits: The Organization of Neuronal Pools.
Convergence A mechanism for providing input to a single neuron from multiple sources

46 Figure 13-13c Neural Circuits: The Organization of Neuronal Pools.
Serial processing c A mechanism in which neurons or pools work sequentially

47 Figure 13-13d Neural Circuits: The Organization of Neuronal Pools.
Parallel processing A mechanism in which neurons or pools process the same information simultaneously

48 Figure 13-13e Neural Circuits: The Organization of Neuronal Pools.
Reverberation A positive feedback mechanism

49 13-6 Reflejos Reflejos Respuestas automáticas, rápidas, coordinadas aun estímulo, en el cordón espinal Interconecciones de neuronas sensoriales interneuronas y motoras

50 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

51 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

52 Figure 13-14 Spinal Reflexes (Part 1 of 4).
2 Dorsal root Arrival of stimulus and activation of receptor 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 Ventral root KEY 4 Sensory neuron (stimulated) Activation of a motor neuron Excitatory interneuron Motor neuron (stimulated)

53 13-6 Reflejos Clasificación
Clasificación de los reflejos de acuerdo a: Desarrollo temprano Respuesta motora Complejidad del circuito Lugar de procesamiento

54 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

55 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

56 Figure 13-15 The Classification of Reflexes.
can be classified by development response complexity of circuit processing site Innate Reflexes Somatic Reflexes Monosynaptic Spinal Reflexes • Genetically determined • Control skeletal muscle contractions • One synapse • Processing in the spinal cord • Include superficial and stretch reflexes Acquired Reflexes Visceral (Autonomic) Reflexes Polysynaptic Cranial Reflexes • Learned • Control actions of smooth and cardiac muscles, glands, and adipose tissue • Multiple synapses (two to several hundred) • Processing in the brain

57 13-7 Espinales Aumentan en nivel de complejidad Monosinapticos
Polisinapticos Intersegmentarios Varios segementos Respuestas que varian en complejidad

58 13-7 Espinales Monosinapticos De Estiramientos De sensorial a motora
Poco retraso Receptor : huso muscular

59 Figure 13-14 Spinal Reflexes (Part 2 of 4).
Receptor (muscle spindle) Stretch Spinal cord REFLEX ARC Stimulus Effector Contraction KEY Response Sensory neuron (stimulated) Motor neuron (stimulated)

60 Figure 13-16 A Muscle Spindle.
Gamma efferent from CNS Extrafusal fiber To CNS Sensory region Intrafusal fiber Muscle spindle Gamma efferent from CNS

61 13-7 Espinales Posturales Estiramientos Postura erecta
Músculos que se estiran reaccionan contrayéndose y se mantiene un balance Tensión acumulada, fatiga muscular

62 13-7 Espinales Polisinapticos Complicados Interneuronas
Balance entre EPSP e IPSP

63 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

64 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

65 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) Painful stimulus

66 13-8 El Cerebro puede alterar los reflejos espinales
Babinski Normal en infante Anormal en adulto Puede indicar daño al SNC en adultos

67 Figure 13-17a The Babinski Reflexes.
The plantar reflex (negative Babinski reflex), a curling of the toes, normal in healthy adults.

68 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.