Chapter 13 review questions

Question 1

Define spinal reflex

Answer 1

rapid, automatic response to some stimulus

Question 2

spinal reflexes are controlled where?

Answer 2

in the spinal cord

Question 3

cranial nerves and spinal nerves are part of the peripheral or central nervous system? (CNS or PNS)

Answer 3

PNS

Question 4

identify the 3 spinal meninges from outermost (superficial) to innermost (deep)

Answer 4

outermost = dura mater
arachnoid mater
innermost = pia mater

Question 5

damage to which root of the spinal nerve would interfere with motor function

Answer 5

ANTERIOR ROOT (ventral) – composed of visceral and somatic motor fibers

posterior = sensory info – visceral + somatic sensory fibers
anterior = motor info

Question 6

where is the cerebrospinal fluid that surrounds the spinal cord located?

Answer 6

beneath the arachnoid mater and superficial to the pia mater — in the SUBARACHNOID SPACE

Question 7

Differentiate between sensory nuclei and motor nuclei

Answer 7

sensory nuclei – receive and relay sensory information from peripheral receptors

motor nuclei – issue motor commands to peripheral effectos

Question 8

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

Answer 8

the anterior gray horns of the spinal cord
–where the cell bodies of somatic motor neurons are located

Question 9

a disease that damages myelin sheaths would affect which portion of the spinal cord?

Answer 9

the COLUMNS in the white matter of the spinal cord.
–the columns are composed of myelinated axons

Question 10

identify the major network of nerves known as plexuses

Answer 10

cervical plexus
brachial plexus
lumbar plexus
sacral plexus
coccygeal plexus

Question 11

an anesthetic blocks the function of the dorsal rami of the cervical spinal nerves
which areas of the body will be affected?

Answer 11

this would affect the skin and muscles of the back of the neck and shoulders

Question 12

injury to which of the nerve plexuses would interfere with the ability to breathe?

Answer 12

cervical plexus – contains the phrenic nerves which innervate the diaphragm.
this could be fatal

Question 13

compression of which nerve produces the sensation that your leg has “fallen asleep”

Answer 13

sciatic nerve (sacral plexus)

Question 14

Define neuronal pool

Answer 14

a neuronal pool is a functional group of interconnected neurons organized WITHIN THE CNS

Question 15

list the 5 circuit patterns found in neuronal pools

Answer 15

divergence
convergence
serial processing
parallel processing
reverberation

Question 16

define reflex

Answer 16

a reflex is a rapid, automatic response to a specific stimulus.
important mechanism for maintaining homeostasis

Question 17

what is the minimum # of neurons in a reflex arc?

Answer 17

2 – sensory neuron that brings information to the CNS, and a motor neuron that transmits a response to an effector

Question 18

one of the first somatic reflexes to develop is the suckling reflex. what type of reflex is this?

Answer 18

innate reflex

Question 19

identify the basic characteristics of polysynaptic reflexes

Answer 19

-involve pools of interneurons
-intersegmental in distribution
-involve reciprocal inhibition

Question 20

for the patellar reflex, how would the stimulation of the muscle spindle by gamma motor neurons affect the speed of the reflex?

Answer 20

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

Question 21

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 ??

Answer 21

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

Question 22

during a withdrawal reflex of the foot, what happens to the limb on the side opposing the stimulus?
what is this response called?

Answer 22

during a withdrawal reflex, the limb on the opposite side is extended.

this response is called the cross extensor reflex

Question 23

define reinforcement as it pertains to spinal reflexes

Answer 23

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

Question 24

after injuring her back, Tina exhibits positive babinski reflex. what does this indicate about her injury?

Answer 24

possible damage of descending tracts in the spinal cord

Question 25

why are spinal nerves called mixed nerves?

Answer 25

because they contain sensory AND motor fibers

Question 26

the adult spinal cord extends to….

Answer 26

L1 or L2 vertebra

Question 27

what matter is primarily involved in relaying information to the brain?

Answer 27

white matter – because it is myelinated and faster

Question 28

what is a dermatome?

Answer 28

a sensory region monitored by the dorsal rami of a single spinal segment

Question 29

what is the phrenic nerve

Answer 29

the major nerve of the CERVICAL PLEXUS that innervates the diaphragm

Question 30

the genitofemoral, femoral, and lateral femoral cutaneous nerves are major nerves of which plexus?

Answer 30

lumbar plexus

Question 31

the synapsing of several neurons on the same postsynaptic neuron is called…

Answer 31

convergence

Question 32

what are the reflexes that control the most rapid, stereotyped motor responses to stimuli?

Answer 32

monosynaptic reflexes

Question 33

give an example of a stretch reflex triggered by passive muscle movement

Answer 33

patellar reflex

Question 34

the contraction of flexor muscles and the relaxation of extensor muscles illustrates the principle of…..

Answer 34

reciprocal inhibition

Question 35

reflex arc in which the sensory stimulus and motor response occur on the SAME SIDE of the body are called….

Answer 35

ipsilaterla

Question 36

explain the anatomical significance of the fact that spinal cord growth ceases at age 4

Answer 36

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

Question 37

list, in sequence, the 5 steps involved in a neural reflex

Answer 37

1. arrival of stimulus and activation of receptor
2. activation of sensory neurons
3. information processing
4. activation of a motor neuron
5. response by an effector (muscle, gland, or adipose tissue)

Question 38

WHY can polysynaptic reflexes produce far more complicated reflexes than monosynaptic?

Answer 38

because the interneurons involved can control several muscle groups

Question 39

why do cervical nerves outnumber cervical vertebrae?

Answer 39

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

Question 40

if the anterior gray horns of the spinal cord were damaged, what type of control would be affected?

Answer 40

loss in motor control

Question 41

list all of the CNS sites where cerebrospinal fluid (CSF) is located.

what is the function of CSF?

Answer 41

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

Question 42

what FIVE characteristics are common to all polysynaptic reflexes?

Answer 42

-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

Question 43

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?

Answer 43

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

Question 44

the subarachnoid space contains….

Answer 44

CSF (cerebrospinal fluid)

Question 45

Side to side movements of the spinal cord are prevented by the….

Answer 45

dendiculate ligaments

Question 46

ascending tracts carry…..

Answer 46

sensory information to the brain

Question 47

what effect does stimulation of a sensory neuron that innervates an intrafusal muscle fiber have on muscle tone?

Answer 47

this will increase muscle tone

Question 48

which nerve is involved:

someone sleeps with a flexed wrist and when she wakes up in the morning her thumb and forefinger are “asleep”

Answer 48

the median nerve

Question 49

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?

Answer 49

the radial nerve

Question 50

injury to anterior horn of the lumbar region

what would be the result?

Answer 50

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)

Question 51

look at # 3o

Answer 51

in text – look bitch