Chapter 24:
The Spine
Reflexes
 Many of the body’s reflexes allow
for testing of nervous system
integrity.
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2
Patellar (Knee-Jerk) Reflex
 This commonly tested reflex is
accomplished by tapping the
patellar tendon, which stretches the
quadriceps muscle, stimulating that
muscle’s stretch receptors.
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Patellar (Knee-Jerk)
Reflex (cont.)
 A nerve signal is sent to the spinal
cord, which reflects back through a
motor neuron to the quadriceps and
causes contraction.
 Quadriceps contraction causes the
lower leg to extend.
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4
Flexor (Withdrawal) Reflex
 This reflex is usually activated in
response to some potentially
injurious stimulus, such as stepping
on a sharp or hot object.
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Flexor (Withdrawal)
Reflex (cont.)
 A receptor located in the skin
responds to pain. A nerve signal is
sent to the spinal cord, where it
reflects through a motor neuron to
flexor muscles such as the leg’s
hamstrings, causing the limb to pull
away from the stimulus.
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Plantar Reflex
 Tests the integrity of the lower
spinal cord.
 A reflex hammer is pulled along the
sole of the foot with pressure
applied.
 The normal response is a curling of
the toes.
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Plantar Reflex (cont.)
 If damage is present, an abnormal
reflex response is a spreading of
the toes and lifting of the big toe,
also known as Babinski’s sign.
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8
Nervous System Anatomy
 Although other cells help with
support and nourishment, the only
cell that can communicate impulses
to other cells is the neuron.
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9
Gray and White Matter
 Gray matter consists mostly of
neuron cell bodies.
 White matter consists mostly of
myelinated nerve fibers.
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10
Gray and White
Matter (cont.)
 Gray matter is found in the center of
the spinal cord and is surrounded
by white matter.
 In the brain there is an additional
outer gray matter layer, the cerebral
cortex.
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11
Spinal Injuries
 Trauma to the spine can produce
devastating injuries, including
paralysis and death.
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12
Jaw-Thrust Maneuver
 This is the safest method to restore
breathing when neck injury is
suspected.
 The mandible is brought forward by
placing fingers behind the jaw angle
and lifting.
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13
Intervertebral
Disc Herniation
 A structural defect in which the
softer nucleus pulposus protrudes
through the tough annulus fibrosus
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