Spinal Cord Flashcards
What are the six characteristics of the spinal cord?
- vertebrae + 3 meninges + CSF
- 5 regions
- spinal cord extends to L1 vertebrae
- anterior median fissure + posterior median sulcus
- rootlets
- gray and white matter
What are the five regions of the spinal cord?
cervical, thoracic, lumbar, sacral, and cauda equina
Each region of the spinal cord gives rise to what?
spinal nerves
How many spinal nerves does the cervical region have?
eight
How many spinal nerves does the thoracic region have?
twelve
How many spinal nerves does the lumbar region have?
five
How many spinal nerves does the sacral region have?
five
How many spinal nerves does the cauda equina region have?
one
The L1 vertebrae is only present in what?
adults
Where is the L1 vertebrae located?
below the cauda equina
What are the two kinds of rootlets?
dorsal and ventral roots
What does a combination of a dorsal and ventral root create?
a spinal nerve
How many pairs of spinal nerves exist?
31
Spinal nerves are what kind of nerves?
mixed
What is a mixed nerve?
nerves that perform both the action of sensory nerves as well as a motor nerve
The dorsal root contains what kind of nerves?
sensory nerves/neurons
The dorsal horn contains what kind of nerves?
interneurons
Spinal cord gray and white matter location
gray matter: inside
white matter: outside
The ventral horn contains what kind of nerves?
motor nerves/neurons
The ventral root contains what kind of nerves?
motor nerves/neurons
Spinal cord gray matter function
signal integration (processing):
- spinal cord manages some basic REFLEXES
Spinal cord white matter function
signal propagation (conduction)
Define reflex
rapid, pre-programmed involuntary response to a certain stimulus
Define reflex arc
is a neural pathway
What are the three types of reflexes?
- spinal vs. cranial
- somatic vs. autonomic (visceral)
- innate vs. acquired
The somatic nervous system controls what?
skeletal muscle
The autonomic nervous system controls what?
smooth muscle, cardiac muscle, and glands
Innate vs. acquired =
born with it vs. developed over time
The gray matter in the spinal cord is responsible for what?
reflexes
The white matter in the spinal cord does what?
forms columns organized into sensory/motor tracts that act as parts of bigger sensory/motor pathways
Sensory (ascending) pathways function
inform about the changes in the internal/external environment
What three nerves are sensory pathways composed of (first to last)?
- primary nerve
- secondary nerve
- tertiary nerve
Most sensory pathways pass through what?
thalamus (filter)
Motor (descending) pathways function
regulation of activity (excitation/inhibition)
What two nerves are motor pathways composed of (first to last)?
- upper nerves
- lower nerves
The nervous system is split into what two systems to achieve certain goals?
somatic NS and autonomic NS
Somatic NS function/goal
conscious perception + voluntary control
What are the two components of the somatic NS?
somatic sensory and motor pathways?
Autonomic NS function/goal
maintain homeostasis by:
- regulating (internal processes)
- adjusting (stress vs. rest)
What are the two components of the autonomic NS?
autonomic sensory and motor pathways?
Somatic motor pathways utilize what neurotransmitter?
acetylcholine (ACh)
Somatic motor pathway structure
- no ganglion
- lower motor neuron
Somatic motor pathways cause what kind of response?
excitation
Autonomic motor pathways utilize what neurotransmitter?
acetylcholine (ACh) and norepinephrine
Autonomic motor pathway structure
- ganglion
- preganglionic lower motor neuron
- postganglionic lower motor neuron
Autonomic motor pathways cause what kind of response?
excitation or inhibition
What are the two autonomic NS divisions?
parasympathetic and sympathetic
What is another name for parasympathetic?
craniosacral
What is another name for sympathetic?
thoracolumbar
Parasympathetic aka…
“rest and digest”
Parasympathetic function
conserves energy, replenishes nutrients in rest
Craniosacral communicates through what?
spinal and cranial nerves
Sympathetic aka…
“fight or flight”
Sympathetic function
alters the body’s activities in stress (EEE):
- emergency
- exercise
- excitement
Thoracolumbar communicates through what?
spinal nerves
Parasympathetic nerves have a _____ preganglionic neuron and a _____ postganglionic neuron.
long, short
Sympathetic nerves have a _____ and ______ preganglionic neuron and a _____ postganglionic neuron.
short, branched, long
What is the function of the branching preganglionic neuron?
mass activation
Most organs are constantly under what?
dual innervation
Dual innervation
contains both parasympathetic and sympathetic divisions
Autonomic nerves work in the form of what?
reflexes
How do dual innervated organs work?
when conditions change each division will excite or inhibit organ stimulation for optimal organ performance
What organs/structures only contain sympathetic neurons??
- blood vessels
- sweat glands
- hair muscles
What three structures regulate the autonomic NS?
hypothalamus, brain stem, and spinal cord
Hypothalamus regulation of autonomic nervous system
Master control for the autonomic functions
How does the hypothalamus perform control over the autonomic functions?
receives signal from the cortex, thalamus, or the limbic system then COMMUNICATES with different autonomic centers below and COORDINATES their activity
Regulation of autonomic nervous system: brainstem
responsible for reflex centers that control cardiovascular, respiratory, and digestive
Regulation of autonomic nervous system: spinal cord
responsible for the reflex centers that control defecation and urination
