Download CHAPTER 18 CENTRAL NERVOUS SYSTEM – SPINAL CORD

CHAPTER 12
CENTRAL NERVOUS SYSTEM – SPINAL CORD
spinal cord
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CNS below foramen magnum
within vertebral canal
ends at L2 vertebra
functions :
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superhighway between brain and periphery
source of spinal nerves
integration center for reflexes
gross structures
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conus medullaris
end of spinal cord
filum terminale
pia beyond conus medullaris
attaches to coccyx
cauda equina
nerve roots inferior to sp cord
cervical enlargement
thickened for nerves to UE
lumbar enlargement
thickened for nerves to LE
spinal meninges
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continuous from cranial meninges
dura mater
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epidural space
outer
between dura and vertebra
attach to foramen magnum and coccygeal ligament
arachnoid mater
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middle
subarachnoid space
contains CSF
pia mater
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inner
on spinal cord
cross section
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gray matter
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inner area (H pattern)
cell bodies
interneurons
synapses
white matter
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outer area
myelinated axons
up and down spinal cord
central canal
continuation of 4th ventricle
cross section
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dorsal
sensory
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ventral
motor
organization
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gray matter
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ventral
motor cell bodies
dorsal
sensory ; interneurons
white matter
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ventral
motor tracts
dorsal
sensory tracts
nerve roots
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ventral root
peripheral motor neuron
dorsal root
peripheral sensory neuron – axon
gray matter
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integration center -
connect sensory and motor neurons
connect brain and periphery
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anterior horns
cell bodies of motor neurons
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posterior horns
interneurons
terminal axon – sensory neurons
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lateral horns
cell bodies – ANS neurons
T1 – L2 only
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gray commissure
connection R & L
white matter
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3 white columns = funiculi
posterior funiculus
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ascending sensory
lateral funiculus
ascending and descending
anterior funiculus
descending motor (mostly)
spinal tracts
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tract =
bundles of neurons (axons) in CNS
spinal tracts are organized by :
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sensory vs motor
neuron type
pain, touch, motor
direction
ascending ; descending
body location
hand, heart, brain center
decussation
crossover to other side of body
spinal tracts 2
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ascending tracts
sensory neurons to brain
(from peripheral nerve)
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descending tracts
motor neurons from brain
(to peripheral nerve)
commissural tracts
cross spinal cord
organized by
motor or sensory
origin and destination
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ascending tracts
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dorsal (posterior) white column
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touch, pressure, vibration, proprioception
to what cerebral lobe ?
fasciculus cuneatus
fasciculus gracilis
synapse at medulla and thalamus
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spinothalamic
spine to thalamus
pain, temp, touch, pressure
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spinocerebellar
spine to cerebellum
proprioception
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corticospinal = pyramidal
descending tracts
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motor cortex to spine
motor to muscles
motor cortex
cerebral peduncles
pyramids
decussation
corticospinal tract
anterior horn - synapse with peripheral motor neuron
extrapyramidal :
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rubrospinal
red nucleus to spine (muscle tone)
vestibulospinal
vestibular nuclei (balance)
reticulospinal
spinal nerve roots
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within vertebral foramen
dorsal root
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cell bodies
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dorsal root ganglion
connects to posterior horn of gray matter
synapse with ascending (sensory) tracts
ventral root
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sensory from periphery
sensory neurons
motor to periphery
axon of motor neurons
cell bodies
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anterior horn
post-synaptic neuron from descending (motor) tracts
Neural Pathways
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pathway between periphery and brain - 2 or 3 neurons
• peripheral nerve
• spinal tract
• neuron above thalamus (sensory)
• brain center
sensory pathway
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3 neurons
peripheral sensory neuron
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1st order neuron
receptor, axon
dorsal root
• dorsal root ganglion
posterior horn
ascending spinal tract
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2nd order neuron
synapse at thalamus
neuron above thalamus
3rd order neuron
brain center
motor pathway
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2 (skeletal) or 3 (autonomic) neuerons
brain center
motor cortex
ANS
descending tract
UMN
anterior horn of gray matter
synapse
peripheral motor neuron
LMN
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cell body
anterior horn
ventral root
effector
muscle