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The ventral roots of each spinal segment
control peripheral effectors and contain the axons of somatic motor and visceral motor neurons
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Spinal nerves are called mixed nerves because they
contain sensory and motor fibers
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The adult spinal cord extends only to
the first or second lumbar vertebra
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3 facts of the gray matter of the spinal cord
- It is located in the interior of the spinal cord around the central canal
- It functions in processing neural information
- It contains motor neurons
- It is divided into regions called horns
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Proper sequence of reflex arch
- 1) arrival of a stimulus and activation of a receptor
- 2) activation of a sensory neurons
- 3) information processing
- 4) activation of a motor neuron
- 5) response by an effector
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A sensory region monitored by the doral rami of a single spinal segment is
dermatome
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The major nerve of the cervical plexus that innervates the diaphragm is
phrenic nerve
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The genitofemoral, femoral, and lateral femoral cutaneous nerves are major nerves of the
lumbar plexus
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The synapsing of several neuurons on the same postsynaptic neuron is called
convergence
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The feflexes that control the most rapid, stereotyped motor responses to stimuli are
monosynaptic reflexes
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An example of a stretch reflex triggered by passive muscle movement is the
patellar reflex
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The contraction of flexor muscles and the relaxation of extensor muscles illustrates the principle of
reciprocal inhibition
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Reflex arcs in which the sensory stimulus and teh motor response occur on the same side of the body are
ipsilateral
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Most superficial layer to deep
- 1) walls of vertebral canal
- 2) epidural space
- 3) dura mater
- 4) subdural space
- 5) arachnoid membrane
- 6) subarachnoid space
- 7) pia mater
- 8) spinal cord
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Explain the anatomical significance of the fact that spinal cord grown ceases at age 4
The vertebral column continues to grow, extending beyond the cord. The end of the cord is visible as the conus medullaris near L1, and teh cauda equina extends the remainder of the column
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List, in sequence, the five steops involved in a neural reflex
- 1) arrival of stimulus and activation of receptor
- 2) activation of sensory neuron
- 3) information processing
- 4) activation of a motor neuron
- 5) response by an effector (muscle or gland)
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Polysynaptic reflexes can produce far more complicated responses than can monosynaptic reflexes because
the interneurons involved can control several muscle groups
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Why do cervical nerves outnumber cervical vertebrae
The first cervical nerve exits superior to vertebra C1 (between the skull and vertebra); the last cervical nerve exits inferior to vertebra c7 (between the last cervical vertebra and the first thoracic vertebra). There are thus 8 cervical nerves but only 7 cervical vertebrae
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If the anterior gray horns of the spinal cord were damaged, what type of control would be affected?
The cell bodies of spinal motor neurons are located in the anterior gray horns, so damage to these horns woudl result in a loss of motor control
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List all of the CNS sites were cerebrospinal fluid is located. What are the function of CSF?
Within the CNS, CSF fills the central canal, the ventricles, and the subarachnoid space. CSF acts as a schock absorber and a diffusion medium for dissolved gases, nutrients, chemical messengers, and waste products.
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What 5 characteristics are common to all polysynaptic reflexes
- 1) involvement of pools of interneurons
- 2) intersegmental distribution
- 3) involvement of reciprocal innervation
- 4) motor response prolonged by reverberating circuits
- 5) cooperation of reflexes to produce a coordinated, controlled response
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Predict the effects on the body of a spinal cord transection at C7. How would these effects differ from those of a spinal cord transection at T10
Transection of the SC at C7 would most likely result in paralysis from the neck down. Transection at T10 would produce paralysis and eliminate sensory input in the lower half of the body only.
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The subarachnoid space contains
cerebrospinal fluid
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Side-to-side movements of the spinal cord are prevented by the
denticulate ligaments
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Ascending tracts
carry sensory information to the brain
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What effect does the stimulation of a sensory neuron that innervates an intrafusal muscle fiber have on muscle tone?
Stimulation of the sensory neuron will increase muscle tone
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