Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
236 Cards in this Set
- Front
- Back
What does the spinal cord occupy?
|
spinal canal of the vertebral column
|
|
Where does the spinal cord begin and terminate?
|
forament magnum and conus medullaris
|
|
At what level of vertrebrae is the conus medullaris?
|
L1-L2
|
|
How many spinal cord segments are there?
|
31
Each has a pair of spinal nerves delineating from it |
|
How are the spinal nerves connected to the cord?
|
Via the posterior (dorsal) and anterior (ventral) roots
|
|
Posterior (dorsal) Root
|
Area that sensory (afferent) information enters the cord
|
|
Ventral (anterior) Root
|
Area that motor (efferent) activity leaves the cord
|
|
Gray matter
|
The H- or butterfly-shaped central region of the spinal cord
|
|
What does gray matter contain?
|
Nerve cell bodies
|
|
Where are the lateral horns (in gray matter) found?
|
segments T1-T12 and L1-L2
|
|
Each segment of the cord has several million neurons in the gray matter, including?
|
sensory relay neurons,
anterior motor neurons, and interneurons |
|
Where are anterior motor neurons located?
|
Anterior (ventral) horns of the gray matter
|
|
When axons leave the cord via the anterior (ventral) roots, what do they innervate?
|
Skeletal muscle fibers
|
|
What are the two types of motor neurons?
|
Alpha motor neurons &
Gamma motor neurons |
|
What gives rise to Large A-alpha nerve axons?
|
Alpha motor neurons
|
|
What do Large A-alpha nerve axons innervate?
|
Extrafusal skeletal muscle fibers
|
|
How much of the total motor neuron pool do alpha motor neurons make up?
|
2/3
|
|
What do gamma motor neurons give rise to?
|
A-gamma axons
|
|
What do A-gamma axons innervate?
|
Intrafusal muscle fibers in muscle spindles
|
|
What makes up about 1/3 of total motorneurons in the anterior horns?
|
Gamma motor neurons
|
|
Are gamma motor neurons smaller or larger than alpha motor neurons?
|
Smaller
|
|
Where does most of the input to the motor neurons come from?
|
Interneurons
|
|
Where are interneurons found?
|
All areas of the gray matter
|
|
What are the most numerous cells in gray matter?
|
Interneurons
- 30x more than alpha motor neurons |
|
Are interneurons in the gray matter inhibitory or excitatory?
|
Both
|
|
Where is most motor activity descending from the brain directed to first?
|
Interneurons
|
|
Why is white matter white?
|
Myelination
|
|
What does white matter contain?
|
Numerous bundles (tracts)
|
|
What are examples of ascending tracts in white matter?
|
Lateral spinothalamic &
Posterior spinothalamic tracts |
|
What are lateral spinothalamic tracts for?
|
Principal pathway for pain and temperature transmission
|
|
What is the prinicipal pathway for transmission of tactile and proprioceptive sensations?
|
Posterior spinothalamic tracts (dorsal columns)
|
|
What tract originates in the brain and travels down the cord?
|
Descending tracts
|
|
What motor nerve tract that originates in the motor cortex and terminates primarily on interneurons in the spinal cord gray matter?
|
corticospinal (pyramidal) tracts
|
|
Where do nerve tracts associated with the sympathetic nervous system originate and terminate?
|
in the brainstem and terminate in spinal segments T1-T12 and L1-L2
|
|
What are the three layers of connective tissue that surround the spinal cord?
|
pia mater
|
|
How far do the dura and arachnoid extend to?
|
level S2
|
|
What does the subarachnoid space contain?
|
CSF
|
|
What does the epidural space contain?
|
fat
|
|
Where does the epidural space extend from and go to?
|
from the foramen magnum to the sacral hiatus
|
|
Where does the ligamentum flavum lie?
|
just posterior to the epidural space
|
|
What supplies blood to the spinal cord?
|
vertebral arteries and thoracic and abdominal aorta
|
|
What is the single midline vessel that supplies the anterior 2/3 of the cord?
|
anterior spinal artery
|
|
What paired vessels supply the posterior 1/3 of the cord?
|
posterior spinal arteries
|
|
Where does the anterior spinal artery originate?
|
from the vertebral arteries at base of skull
|
|
Where do the posterior spinal arteries originate from?
|
posterior cerebellar arteries
|
|
What supplies BOTH the anterior and posterior spinal arteries?
|
radicular arteries
|
|
What is a single branch of the aorta
|
that almost always arises on the left side?
|
|
Where is the origin of the artery of adamkiewicz in 60% of individuals?
|
T9-T12
|
|
Where is the artery of adamkiewicz in 25% of individuals?
|
L1-L2
|
|
Where is the artery of adamkiewicz in 15% of individuals?
|
T5-T8
|
|
What does the artery of adamkiewicz supply?
|
nearly all the blood flow to the lower thoracic and lumbar cord
|
|
What may result from injury to the artery of adamkiewicz?
|
spinal cord ischemia
|
|
What can result from spinal cord ischemia?
|
paraplegia
|
|
Give examples of how spinal cord ischemia can happen?
|
surgical dissection or aortic cross-clamping
|
|
What are formed by the joining of the anterior and posterior roots at each of the spinal cord segments?
|
spinal nerves
|
|
Where do spinal nerves exit the vertebral column?
|
intervertebral foramina
|
|
How many pairs of spinal nerves are there?
|
31
|
|
Where do the lower lumbar and sacral nerve descend before they exit the vertebral column?
|
cauda equina
|
|
How many cervical spinal nerves?
|
8
|
|
How many thoracic spinal nerves?
|
12
|
|
How many lumbar spinal nerves?
|
5
|
|
How many sacral spinal nerves?
|
5
|
|
how many coccygeal spinal nerves?
|
1
|
|
Why are spinal nerves called mixed nerves?
|
they contain somatic (sensory and motor) and autonomic nerve fibers
|
|
What does each spinal segment supply?
|
specific region of skin (dermatone) and skeletal muscle
|
|
What are the two major branches of spinal nerves?
|
anterior and posterior ramus
|
|
What supplies long muscles of the back and tissue overlying them?
|
posterior primary division (posterior ramus)
|
|
What is the main portion of the spinal nerve called?
|
anterior primary division (anterior ramus)
|
|
What is a intermingling collection of nerves that emanate from different cord segments?
|
plexus
|
|
What joins to form the cervical plexus in the neck?
|
anterior rami of spinal nerves C1-C4
|
|
What emerges to innervate the diaphragm?
|
phrenic nerve
|
|
What do peripheral nerves emerging from the cervical plexus supply?
|
skin and muscles of the neck and posterior scalp
|
|
What joins to form the brachial plexus?
|
anterior rami of spinal nerves C5-C8 and T1
|
|
Peripheral nerves from the brachial plexus innervate what?
|
upper limbs
|
|
What joins to form the lumbosacral plexus?
|
anterior rami of spinal nerves L1-L5 and S1-S4
|
|
Peripheral nerve emerge from the lumbosarcral plexus to innervate what?
|
the lower limbs and pelvis
|
|
What provides continuous feedback information to the CNS with respect to muscle length and tension and the rate of change of muscle length and tension during movement?
|
muscle receptors (proprioceptors)
|
|
Where is feedback information for muscle receptors directed to?
|
spinal cord
|
|
What are the two types of muscle receptors?
|
muscle spindles and golgi tendon organs
|
|
What do muscle spindles function as?
|
stretch receptors and detect changes in muscle length
|
|
What are muscle spindles made up of?
|
intrafusal muscle fibers
|
|
What are the muscle spindles attached to?
|
glycocalyx of surrounding extrafusal fibers
|
|
The central region of the spindle is innervated by sensory nerves
|
what type?
|
|
The end portions of the intrafusal fibers contain actin and myosin and are innervated by?
|
A-gamma motor fibers
|
|
What are sensory receptors located in the muscle tendons near the point of attachment of the tendons to the skeletal muscle fibers?
|
golgi tendon organs
|
|
What are golgi tendon organ receptors sensitive to?
|
tension developed within the muscle
|
|
What sensory nerves transmit information from the golgi tendon organs to the CNS?
|
Type Ib
|
|
Where are Type Ib signals directed to?
|
spinal cord
|
|
What is unique of the monosynaptic reflex?
|
very little delay
|
|
What do the knee-jerk reflex and other muscle jerk reflexes test?
|
excitability of motor neurons
|
|
What is elicited most often by a painful stimulus?
|
flexor (withdrawal) reflex
|
|
Flexion of one limb is accompanied by extension of the opposite limb is called?
|
crossed extension
|
|
What also acts over long distances of the spinal cord to control reciprocal limb movements during locomotion?
|
crossed extension
|
|
What does crossed extension prevent?
|
disturbance of equilibrium
|
|
What represents a reflex response to irritations of muscle?
|
muscle spasm
|
|
What can cause contraction (spasm) of abdominal mucsles?
|
peritonitis
|
|
What can can local muscle spasms or cramps?
|
ischemia
|
|
Lesion to the spinal cord can result from a variety of insults
|
name them?
|
|
What happens during spinal cord transection during the initial period of spinal shock?
|
both somatic and autonomic reflexes below the lesion are temporarily interrupted - decrease in blood pressure
|
|
Spinal neurons below the lesion (in spinal transection) regain excitability and some reflex activity
|
but what is still lost?
|
|
What is overactivity of the sympathetic nervous system?
|
autonomic hyperreflexia
|
|
With whom is autonomic hyperreflexia commonly seen?
|
patients with cord transections at T5 or above (unusual with lesions below T10)
|
|
What can trigger strong autonomic responses below the level of transection?
|
cutaneous (incision) or visceral (distended bladder) stimulation
|
|
What does sympathetic discharge below the lesion cause?
|
intense vasoconstriction (increase BP)
|
|
What does sympathetic discharge above the lesion cause?
|
reflex bradycardia and vasodilation
|
|
What is Brown-Sequard syndrome?
|
hemisection of spinal cord
|
|
State characteristics of brown-sequard syndrome?
|
1) loss of sensation/hypotonic paralysis @ level of injury (same side)
|
|
2) below lesion - same side = loses tactile
|
sensory capacity
|
|
3) below lesion - opposite side = loss of pain/temp sensation
|
no loss of motor function
|
|
What is it called when local anesthetics are injected into the subarachnoid space of the spinal cord?
|
Spinal block
|
|
Where is a spinal block injection usually performed?
|
below the end of the spinal cord (L3-L4 or L4-L5)
|
|
Where is the uptake of local anesthetics into?
|
spinal nerve roots
|
|
What does not alter local anesthetic in CSF?
|
CSF circulation
|
|
What are the two complications associated with spinal blocks?
|
hypotension and postspinal headache
|
|
What occurs as a result of CSF leakage from puncture site?
|
postspinal headache
|
|
What is caused by a reduction of CSF pressure in the subarachnoid space that causes tension in the meninges?
|
post-spinal headache
|
|
what happens when the sympathetic nervous system blockade can cause venous pooling of blood and decreased venous return and cardiac output?
|
hypotension
|
|
What is placement of local anesthetics into the epidural space of the spinal cord?
|
epidural block
|
|
Where is the major site of action for epidural blocks?
|
spinal nerve roots
|
|
Is onset of epidural block faster or slower than spinal block?
|
slower
|
|
What nerves are blocked during epidurals?
|
sympathetic
|
|
Sensory receptors are usually what?
|
nerve endings
|
|
Receptors act as transducers to what?
|
convert the natural form of the stiumulus into electrical impluses - action potentials
|
|
What are necessary for the nervous system to process a sensory event?
|
electrical impulses (action potentials)
|
|
What is the magnitude of the receptor potential determined by?
|
stimulus strength
|
|
The stimulus causes a change in membrane permeability of the receptor and then?
|
DEPOLARIZATION
|
|
What happens if receptor potentials reach threshold?
|
action potentials are generated
|
|
What is the receptor potential analogous to?
|
the excitatory postsynaptic potentials in the CNS
|
|
what is the frequency of action potentials produced by the receptor proportional to?
|
magnitude of receptor potential
|
|
All sensory receptors have receptor fields
|
which are?
|
|
all sensory receptors show some degree of what?
|
adaptation to a stimulus
|
|
What are the 5 types of sensory receptors?
|
mechanoreceptors
|
|
What do mechanoreceptors detect?
|
mechanical deformation of tissue
|
|
What do thermoreceptors detect?
|
detect changes in tissue temperature both cold and warmth
|
|
Nociceptors detect?
|
tissue injury (pain)
|
|
electromagnetic receptors detect?
|
light waves
|
|
chemoreceptors detect?
|
changes in the chemical composition of the local environment (PO2
|
|
sensory nerves transmit action potentials from _______ to _____?
|
sensory receptors
|
|
What are the two types of sensory nerves?
|
type A and Type C fibers
|
|
Which spinal nerves are myelinated?
|
Type A fibers
|
|
What are the subgroups of Type A fibers?
|
alpha
|
|
What are small diameter
|
non-myelinated fibers?
|
|
What comprises more than 50% of peripheral somatic sensory nerve fibers?
|
Type C Fibers
|
|
What are the "special" senses?
|
vision
|
|
What arises from the body surface as well as from deep tissues such as viscera
|
muscles
|
|
What are 5 somatic sensations?
|
tactile sensations
|
|
What are tactile sensations?
|
touch
|
|
What are proprioceptive sensations?
|
limb position and joint angle
|
|
What is kinesthesis?
|
body and limb movement
|
|
What are found extensively in the skin and detect touch and pressure?
|
free nerve endings
|
|
Most tactile sensory receptors transmit sensory signals to the CNS via?
|
Large
|
|
free nerve endings transmit signals via?
|
smaller A-delta fibers and unmyelinated type C fibers (itch
|
|
sensory information enters the spinal cord via the dorsal roots and is directed to the brain via?
|
dorsal columns
|
|
ascending fibers synapse in the dorsal column nuclei in the medulla and cross-over and pass upward to the thalamus via?
|
medical lemniscus pathway
|
|
fibers in the medial lemniscus synapse with?
|
specific sensory relay nuclei in the thalamus
|
|
3rd order fibers project from Sensory relay nuclei in the thalamus to the?
|
somatic sensory cortex
|
|
where is the body "map" preserved?
|
dorsal column lemniscal system and thalamus
|
|
a signal originating in a peripheral sensory nerve is transmitted where?
|
cerebral cortex (where intensity of signal is preserved)
|
|
Where is the somatic sensory cortex?
|
anterior portions of the parietal lobes
|
|
What are the two areas that are involved in the ssc?
|
SS area I and SS area II
|
|
Where is the somatic sensory area I located?
|
postcentral gyrus
|
|
How are the areas of the body represented within SS I?
|
according to the density of their sensory receptors (sensory homunculus)
|
|
What is highly represented in the sensory homunculus?
|
lips
|
|
Injury to SS I can cause what?
|
1) loss of discrete tactile sense
|
|
What is located in the parietal lobe behind SS I?
|
somatic association cortex
|
|
Where does the somatic association cortex receive input from?
|
SS I
|
|
What plays an important role in the INTERPRETATION of sensory information?
|
somatic association cortex
|
|
What can damage to the somatic association cortex cause?
|
astereogeneis (inability to identify an object by touch without visual input)
|
|
What is it called when one forgets that one side of the body exists?
|
amorphosynthesis
|
|
Position sense and kinesthesis are what kind of sensations?
|
proprioceptive
|
|
Where are proprioceptive receptors located?
|
joint capsules and ligaments
|
|
Give examples of joint capsule and ligament receptors?
|
ruffini end-organs and golgi tendon organs
|
|
Where is transmission of proprioceptive information?
|
dorsal column - lemniscal system
|
|
What is an unpleasant sensory and emotional experience associated with actual or potential tissue damage?
|
pain
|
|
Why is pain just not a physiological process?
|
it is an experience that is affected by past events
|
|
What are the two types of pain?
|
fast (first) pain and slow (second) pain
|
|
What is fast pain AKA?
|
acute
|
|
What arises primarily in skin
|
not felt in deeper tissues and is well-localized?
|
|
Fast pain signals are transmitted to the CNS via?
|
type A-delta sensory nerve fibers
|
|
What is slow pain aka?
|
throbbing
|
|
What is the onset of slow pain?
|
slower than fast pain (obviously) usually 1 second or more
|
|
What can arise from skin and deeper tissues and if often poorly localized?
|
slow pain
|
|
Slow pain signals are transmitted to the CNS via?
|
type C nerve fibers (non-myelinated)
|
|
What are the majority of free nerve endings called?
|
pain receptors (nociceptors)
|
|
What do pain receptors respond to?
|
mechanical
|
|
Where are nociceptors located?
|
somatic (skin
|
|
What can persistent stimulation of pain receptors cause?
|
increase in sensitivity (hyperalgesia)
|
|
Where do type A-delta axons synapes with second-order neurons?
|
laminae I (in gray matter)
|
|
Where do type C axons primarily synapse with interneurons?
|
Laminae II (substantia gelatinosa) and III
|
|
(type C)After synapses with interneurons in laminae II and III where do they project signals?
|
second-order neurons in Lamina V
|
|
What kind of second-order neurons are most abundant in laminae V?
|
wide dynamic range
|
|
Axons of second-order neurons immediately do what?
|
cross over to opposite side of cord
|
|
After second order neurons cross over to the opposite side of cord where do they ascend?
|
lateral spinothalamic tracts
|
|
Where is fast pain primarily directed to?
|
ventrobasal nuclei of the thalamus --> third-order neurons to the somatic sensory cortex
|
|
Where is slow pain primarily directed to?
|
midbrain reticular formation
|
|
What does slow pain do when transmitted to limbic system?
|
causes emotional arousal and activation of descending inhibitory pathways
|
|
What is the periaqueductal gray area?
|
gray matter that surrounds the acqueducts of sylvius (which connects the 3rd and 4th ventricle)
|
|
What is another name for a chemical mediator of pain?
|
alogen
|
|
What is released from injured tissue to directly stimulate free nerve endings?
|
bradykinin and prostaglandin E2
|
|
What other alogens are released from injured cells?
|
K+ and H+
|
|
What alogen is released from tissue mast cells?
|
histamine
|
|
What is primary hyperalgesia mediated by?
|
alogens such as histamine and serotonin
|
|
Local collateral axons terminals of pain afferent nerves release ________ which stimulates mast cells and platelets to release alogens
|
substance P
|
|
Another name for when afferent nerves release substance P?
|
antidromic release
|
|
What is manifested by enhanced pain response to stimuli outside area of injury?
|
secondary hyperalgesia
|
|
In the dorsal horn
|
what do afferent pain fibers release?
|
|
What does glutamate activate in the post-synaptic membrane?
|
AMPA and NMDA receptors
|
|
What does substance P activate in the post-synaptic membrane?
|
Nk-1 receptors
|
|
What is a common mechanism of central sensitization?
|
increased intracellular calcium
|
|
What does glutamate binding to the NMDA receptors cause?
|
removal of Mg+2 block and increased calcium permeability
|
|
What does central sensitization greatly enhance?
|
pain signal transmission and pain perception
|
|
When central sensitization is established what happens?
|
very difficult to interrupt
|
|
The periaqueductal gray area receives ascending slow pain activity which activates what?
|
descending adrenergic tracts to the spinal cord and descending enkephalin-secreting tracts to the raphe magnus nucleus
|
|
Activation of the raphe magnus nucleus causes?
|
activation of descending serotoninergic tracts to spinal cord
|
|
What do descending adrenergic axons in the dorsal horn release?
|
norepinephrine
|
|
What happens after release of norepinephrine in adrenergic axons?
|
activations of pre-synaptic and post-synaptic alpha-2 receptors
|
|
What happens when alpha-2 receptors are activated?
|
inhibition of pain neurotransmission
|
|
descending serotoninergic axons stimulate interneurons to release?
|
enkephalins
|
|
Enkephalins bind to presynaptic opiod receptors on pain afferents and inhibit release of what?
|
substance P
|
|
What happens with release of endorphins in the periaqueductal gray area and limbic system?
|
interference with pain transmission and modulation of pain perception
|
|
Where are beta-endorphin and dynorphin released in?
|
periaqueductal gray area and limbic system in response to pain
|
|
What acts in the spinal cord to inhibit pain transmission?
|
met-enkephalin and leu-enkephalin
|
|
What pain is percieved in a part of the body that is removed from the actual site of painful stimulus?
|
referred pain
|
|
Pain originated in the viscera is referred where?
|
to the body surface
|
|
What doesn't the viscera contain?
|
somatic sensory receptors except for pain receptors
|
|
pain receptors are sparsely distributed where?
|
in the viscera
|
|
highly localized tissue damage can cause what?
|
very little visceral pain
|
|
visceral pain typically involves diffuse activation of pain receptors due to?
|
ischemia
|
|
visceral pain is transmitted to the CNS via?
|
autonomic type C sensory fibers
|
|
Give examples of visceral pain?
|
cardiac ischemia
|
|
What causes parietal pain?
|
injury or disease to a visceral organ which may affect the parietal wall
|
|
parietal pain is transmitted to the spinal cord via?
|
somatic sensory nerves
|
|
example of parietal pain?
|
appendicitis
|
|
what receptors play a critical role in central sensitization?
|
NMDA
|
|
What is a noncompetitive NMDA antagonist?
|
ketamine
|
|
What does pre-emptive acetaminophen do?
|
indirect inhibitor of NMDA receptor
|