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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
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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
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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
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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
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13-2 Cordón Espinal
• Meninges
• Membranas aislantes para el cordón
• Funciones:
• Protección
• Vascularización
• Conectan con las craneales
• Meningitis
• Inflamación por infección Viral o bacteriana
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13-2 Cordon Esponal
• Tres meninges
1. Dura mater
• externa
2. Aracnoide mater
• intermedia
3. Pia mater
• interna
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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
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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
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13-2 Cordon Espinal
• Pia Mater
• Interna
• Colágeno y elastina
• Pegada al cerebro,
• análoga a serosa parietal o visceral?
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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
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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
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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
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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
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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
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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
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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
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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
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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
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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
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13-4 Nervios Espinales y Plexos
• Cervical
• Incluye nervios espinales C1–C5
• Inerva cuello, cavidad toracica y diafragma
• Nervio principal
• Frénico (controla el diafragma)
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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
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Figure 13-10 The Cervical Plexus (Part 2 of 2).
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Figure 13-10 The Cervical Plexus (Part 2 of 2).
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13-4 Nervios Espinales y Plexos
• Braquial
• Incluye nervios espinal C5–T1
• Cintura escapular y extremidades superiores
• Principales
•
•
•
•
•
Musculocutáneo
Mediano
Ulnar
Axillar
Radial
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Figure 13-11a The Brachial Plexus.
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Figure 13-11a The Brachial Plexus.
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Figure 13-11b The Brachial Plexus.
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13-4 Nervios Espinales y Plexos
• Lumbar
• Incluye nervios espinales T12–L4
• Principales
• Genitofemoral
• Femoral
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Figure 13-12a The Lumbar and Sacral Plexuses.
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Figure 13-12a The Lumbar and Sacral Plexuses.
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13-4 Nervios Espinales y Plexos
• Sacral
• Incluye nervios espinales L4–S4
• Principales
• Pudendal
• Ciático
1.
2.
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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
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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
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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
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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
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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
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Figure 13-13b Neural Circuits: The Organization of Neuronal Pools.
b
Convergence
A mechanism for providing
input to a single neuron from
multiple sources
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Figure 13-13c Neural Circuits: The Organization of Neuronal Pools.
c Serial
processing
A mechanism in
which neurons
or pools work
sequentially
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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
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Figure 13-13e Neural Circuits: The Organization of Neuronal Pools.
e Reverberation
A positive feedback
mechanism
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13-6 Reflejos
• Reflejos
• Respuestas automáticas, rápidas, coordinadas
aun estímulo, en el cordón espinal
• Interconecciones de neuronas sensoriales
interneuronas y motoras
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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
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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
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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
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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
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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
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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
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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
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• 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
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13-7 Espinales
• Monosinapticos
•
•
•
•
De Estiramientos
De sensorial a motora
Poco retraso
Receptor : huso muscular
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Figure 13-14 Spinal Reflexes (Part 2 of 4).
Stretch
Receptor
(muscle
spindle)
Spinal cord
REFLEX
ARC
Stimulus
Effector
KEY
Response
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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
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13-7 Espinales
• Posturales
• Estiramientos
• Postura erecta
• Músculos que se estiran reaccionan
contrayéndose y se mantiene un balance
• Tensión acumulada, fatiga muscular
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13-7 Espinales
• Polisinapticos
• Complicados
• Interneuronas
• Balance entre EPSP e IPSP
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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
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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
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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)
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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
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Figure 13-17a The Babinski Reflexes.
The plantar reflex (negative Babinski
reflex), a curling of the toes, normal in
healthy adults.
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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.
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