Transcript The Spinal Cord and Reflexes Notes

Spinal Cord, Spinal
Nerves, and Somatic
Reflexes
Functions of the Spinal Cord
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Conduction – sends information up and
down the cord
Locomotion
Reflexes – involuntary responses to stimuli
The Spinal Cord
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is continuous with the brain and emerges
from the foramen magnum at the base of
the skull
stretches downward for approx. 42 - 45 cm
through the vertebral foramen
there are 31 pairs of spinal nerves that
emerge from the spinal cord through the
intervertebral foramen
Reflexes:
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the simplest responses to a stimulus
Ex. Sneezing and Blinking
produces a rapid motor response to a
stimulus because the Sensory Neuron
synapses directly with a motor neuron in
the Spinal Cord.
are very fast and most never reach the
brain
Meninges
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Enclose the spinal cord
Three layers
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Dura mater – superficial
Arachnoid mater
Pia mater – deep
Space between
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Epidural – between dura
mater and vertebral bone
Subarachnoid – between
arachnoid and pia mater
2 Types of Nerves Radiating from
Spinal Cord
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the dorsal roots contain Neurons that carry
signals to the CNS from various kinds of
Sensory Neurons (Affectors).
the ventral roots contain the Axons of Motor
Neurons, which are neurons that contact
and carry information to the Muscles and
Glands (Effectors).
Gray Matter and White Matter
2 TYPES OF MATTER WITHIN
SPINAL CORD
Gray Matter
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Site of information processing
Contains primarily unmyelinated structures
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Dendrites
Synapses
Looks like a butterfly
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2 dorsal horns
2 ventral horns
Central canal
White Matter
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Carry signals fromone aprt of CNS to
another
Contains myelinated structures
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Primarily axons
Surrounds the gray matter
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Bundles of axons that provide avenues of
communication up and down the spinal cord
Reflexes
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What is a reflex?
Four properties of a reflex
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Stimulation – response to sensory input
Quick
Involuntary
Sterotyped (predictable response)
Reflex Arc