Motor Functions

Question 1

Sensory
signals enter the cord almost entirely through the sen-
sory roots, also know as the posterior or dorsal roots.
True or False

Answer 1

True

Question 2

hese cells are about 30 times as numerous as the anterior motor neurons. hey are small and highly excitable, often exhibiting spontaneous activ-
ity and capable of iring as rapidly as 1500 times per second.

Answer 2

Interneurons

Question 3

responsible for most of the integrative functions of the spinal cord

Answer 3

interneurons and anterior motor neuron

Question 4

inhibitory cells that transmit inhibitory signals to the sur-
rounding motor neurons

Answer 4

Renshaw cells

Question 5

muscle spindle receptor can be excited in two ways:

Answer 5

Lengthening the whole muscle stretches the mid-
portion of the spindle and, therefore, excites the receptor.

contraction of the end portions of the spin- dle’s intrafusal ibers stretches the midportion of the spindle and therefore excites the receptor.

Question 6

the reflex func- tions to oppose sudden changes in muscle length.

Answer 6

dynamic stretch reflex

Question 7

it causes the degree of muscle contraction to remain rea- sonably constant, except when the person’s nervous system speciically wills otherwise.

Answer 7

static stretch reflex

Question 8

Whenever signals are transmitted from the motor cortex or from any other area of the brain to the alpha motor neurons, in most instances the gamma motor neurons are stimulated simultaneously, an efect called

Answer 8

coactivation

Question 9

if the muscle spindle contract and relax along with the large muscle fibers, the receptor portion of the spindle would sometimes be flail and sometimes be overstretched
True or False

Answer 9

False. if the muscle spindle did not contract and relax along with the large muscle ibers, the receptor portion of the spindle would sometimes be lail and sometimes be overstretched,

Question 10

gamma eferent system is excited speciically by signals from

Answer 10

the bulboreticular facilitatory region of the brain stem and, secondarily, by impulses transmitted into the bulboreticular area

Question 11

One of the most important func-

tions of the muscle spindle system is

Answer 11

to stabilize body position during tense motor action