Chapter 13 review questions Flashcards
Define spinal reflex
rapid, automatic response to some stimulus
spinal reflexes are controlled where?
in the spinal cord
cranial nerves and spinal nerves are part of the peripheral or central nervous system? (CNS or PNS)
PNS
identify the 3 spinal meninges from outermost (superficial) to innermost (deep)
outermost = dura mater
arachnoid mater
innermost = pia mater
damage to which root of the spinal nerve would interfere with motor function
ANTERIOR ROOT (ventral) – composed of visceral and somatic motor fibers
posterior = sensory info – visceral + somatic sensory fibers
anterior = motor info
where is the cerebrospinal fluid that surrounds the spinal cord located?
beneath the arachnoid mater and superficial to the pia mater — in the SUBARACHNOID SPACE
Differentiate between sensory nuclei and motor nuclei
sensory nuclei – receive and relay sensory information from peripheral receptors
motor nuclei – issue motor commands to peripheral effectos
a person who has polio has lost the use of his leg muscles.
in which area of his spinal cord would you expect the virus-infected motor neurons to be
the anterior gray horns of the spinal cord
–where the cell bodies of somatic motor neurons are located
a disease that damages myelin sheaths would affect which portion of the spinal cord?
the COLUMNS in the white matter of the spinal cord.
–the columns are composed of myelinated axons
identify the major network of nerves known as plexuses
cervical plexus
brachial plexus
lumbar plexus
sacral plexus
coccygeal plexus
an anesthetic blocks the function of the dorsal rami of the cervical spinal nerves
which areas of the body will be affected?
this would affect the skin and muscles of the back of the neck and shoulders
injury to which of the nerve plexuses would interfere with the ability to breathe?
cervical plexus – contains the phrenic nerves which innervate the diaphragm.
this could be fatal
compression of which nerve produces the sensation that your leg has “fallen asleep”
sciatic nerve (sacral plexus)
Define neuronal pool
a neuronal pool is a functional group of interconnected neurons organized WITHIN THE CNS
list the 5 circuit patterns found in neuronal pools
divergence
convergence
serial processing
parallel processing
reverberation
define reflex
a reflex is a rapid, automatic response to a specific stimulus.
important mechanism for maintaining homeostasis
what is the minimum # of neurons in a reflex arc?
2 – sensory neuron that brings information to the CNS, and a motor neuron that transmits a response to an effector
one of the first somatic reflexes to develop is the suckling reflex. what type of reflex is this?
innate reflex
identify the basic characteristics of polysynaptic reflexes
-involve pools of interneurons
-intersegmental in distribution
-involve reciprocal inhibition
for the patellar reflex, how would the stimulation of the muscle spindle by gamma motor neurons affect the speed of the reflex?
the muscle spindles become more sensitive.
as a result, little if any stretching stimulus would be needed to stimulate the contraction of the quadriceps muscle in the patellar reflex
thus, the reflex response would appear more quickly
a weight lifter is straining to lift a barbell above his head. shortly after he lifts it to his chest height, his muscles appear to relax and he drops the barbell.
which reflex has occurred ??
this response is the tendon reflex
the skeletal muscle relaxes to prevent breaking of the tendons
the receptors are stimulated when the collagen fibers are stretched to a dangerous degree. these receptors activate sensory neurons that stimulate INHIBITORY INTERNEURONS in the spinal cord.
these interneurons innervate the motor neurons in the skeletal muscle. inhibits. no action potential generated so the muscle relaxes and he drops the barbell
during a withdrawal reflex of the foot, what happens to the limb on the side opposing the stimulus?
what is this response called?
during a withdrawal reflex, the limb on the opposite side is extended.
this response is called the cross extensor reflex
define reinforcement as it pertains to spinal reflexes
reinforcement is an enhancement of spinal reflexes.
it occurs when the postsynaptic neuron enters a state of generalized facilitation causes by chronically active excitatory synapses
after injuring her back, Tina exhibits positive babinski reflex. what does this indicate about her injury?
possible damage of descending tracts in the spinal cord
why are spinal nerves called mixed nerves?
because they contain sensory AND motor fibers
the adult spinal cord extends to….
L1 or L2 vertebra
what matter is primarily involved in relaying information to the brain?
white matter – because it is myelinated and faster
what is a dermatome?
a sensory region monitored by the dorsal rami of a single spinal segment
what is the phrenic nerve
the major nerve of the CERVICAL PLEXUS that innervates the diaphragm
the genitofemoral, femoral, and lateral femoral cutaneous nerves are major nerves of which plexus?
lumbar plexus
the synapsing of several neurons on the same postsynaptic neuron is called…
convergence
what are the reflexes that control the most rapid, stereotyped motor responses to stimuli?
monosynaptic reflexes
give an example of a stretch reflex triggered by passive muscle movement
patellar reflex
the contraction of flexor muscles and the relaxation of extensor muscles illustrates the principle of…..
reciprocal inhibition
reflex arc in which the sensory stimulus and motor response occur on the SAME SIDE of the body are called….
ipsilaterla
explain the anatomical significance of the fact that spinal cord growth ceases at age 4
while the spinal cord has stopped growing, the vertebral column CONTINUES to grow into adulthood.
therefore, the spinal cord only extends to around L1 or L2 vertebra, while the cauda equina extends the remainder of the vertebral column
list, in sequence, the 5 steps involved in a neural reflex
- arrival of stimulus and activation of receptor
- activation of sensory neurons
- information processing
- activation of a motor neuron
- response by an effector (muscle, gland, or adipose tissue)
WHY can polysynaptic reflexes produce far more complicated reflexes than monosynaptic?
because the interneurons involved can control several muscle groups
why do cervical nerves outnumber cervical vertebrae?
the 1st cervical nerve enters ABOVE C1 and the last cervical nerve exits BELOW C7.
thus, there are 7 cervical vertebrae but 8 cervical nerves
if the anterior gray horns of the spinal cord were damaged, what type of control would be affected?
loss in motor control
list all of the CNS sites where cerebrospinal fluid (CSF) is located.
what is the function of CSF?
within the CNS, CSF fills the central canal, the ventricles, and the subarachnoid space.
CSF acts as a shock absorber and a diffusion medium for dissolved gases, nutrients, chemical messengers, and waste products
what FIVE characteristics are common to all polysynaptic reflexes?
-involvement of pools of interneurons
-intersegmental distribution
-involvement of reciprocal innervation
-motor response is prolonged by reverberating circuits
-cooperation of reflexes to produce a coordinated, controlled response
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 at C7 would result in paralysis from the neck down.
transection at T10 would produce paralysis and eliminate sensory input from the lower half of the body ONLY
the subarachnoid space contains….
CSF (cerebrospinal fluid)
Side to side movements of the spinal cord are prevented by the….
dendiculate ligaments
ascending tracts carry…..
sensory information to the brain
what effect does stimulation of a sensory neuron that innervates an intrafusal muscle fiber have on muscle tone?
this will increase muscle tone
which nerve is involved:
someone sleeps with a flexed wrist and when she wakes up in the morning her thumb and forefinger are “asleep”
the median nerve
the improper use of crutches can produce a condition known as “crutch paralysis”, characterized by a lack of response by the extensor muscles of the arm, and a condition known as “wrist drop,” consisting of an inability to extend the fingers and wrist.
which nerve is involved?
the radial nerve
injury to anterior horn of the lumbar region
what would be the result?
the anterior horn in the lumbar region contains somatic motor neurons that direct the activity of skeletal muscles of the hip, lower limb, and foot. Karen would have poor motor control of most muscles of the lower limbs, causing difficulty walking and maintaining balance (if she could walk or stand at all)
look at # 3o
in text – look bitch
