Test 3 - Ch 13

Question 1

What are the steps of the motor system to move?

Answer 1

decision - frontal
plan - frontal
speed and project - BG and cerebellum
motor tracts
motor neurons

Question 2

What are all the parts of a muscle fiber

Answer 2

myofibril
sarcomeres-  contractile
-z-line : ends of sarcomere
-m-line : what myosin hangs on
- titin : rubber band that keeps muscle from overstretching and becoming damaged (goes from one end of sarcomere to other
myofilaments
-actin : @ end of myosin and climbs when contraction
-myosin : attached to m-line

Question 3

How does a M contract?

Answer 3

A-alpha brings ACL to t-tubule- EPSP - depolarizes

Mm only relax when gas pedal is not pushed

Question 4

What is occurring when a contracture is present?

Answer 4

Titin does not slack

cross bridges when actin grabs myosin

Question 5

Total M resistance to stretch?

Answer 5

1. Titin - reached elastic limit
2. Active contraction - cross-bridges being formed
3. Weak actin-myosin bonds - lightly stuck velcro
4. Proprioceptive information - m spindles - depolarize motor neurons

Question 6

Where does a LMN/motor neuron cell bodies lie and where does it synapse?

Answer 6

cell bodies- ventral horn of SC

synapses in M

Question 7

How are the motor neurons oriented horizontally in the ventral horn?

Answer 7

medial - core and proximal Mm
Lateral- distal Mm
anterior- extensors
posterior - flexors

Question 8

How are the motor neurons oriented vertically in the ventral horn?

Answer 8

all of cell bodies that contribute to a particular M
cluster into a vertical pool

every spinal level contributes to more than one M

Question 9

What motor neuron makes Mm contract?

Answer 9

A-Alpha

Question 10

What motor neuron makes intrafusal fibers maintain sensitivity?

Answer 10

a-gamma

Question 11

What axon is afferent from M spindle?

Answer 11

1a

Question 12

What does a motor unit consist of?

Answer 12

A motor neuron and all m fibers it connects to

Question 13

Describe a slow twitch M fiber.
size 
metabolism
tension
fatigue

Answer 13

smaller
oxidative
less tension
fatigue resistant

Question 14

Describe a fast twitch M fiber.
size 
metabolism
tension
fatigue

Answer 14

large
glycolytic
high tension
easy fatigue

Question 15

What is fiber placement in gross movement muscles?

Answer 15

many fibers per axon

increase strength, decrease control

Question 16

What is fiber placement in fine movement muscles?

Answer 16

few m fibers/axon

decrease strength, increase control

Question 17

What can any 1 Alpha neuron receive convergent information from?

Answer 17

brain and sensory receptor

deep tendon pressure inhibits alpha motor neuron

Question 18

What is proprioceptive body schema?

Answer 18

self-perpetuation in walking, only need to initiate

need input from GTO

Question 19

What afferents inhibit the alpha efferent to antagonist?

Answer 19

1a

Question 20

Fasiculations

Answer 20

quick twitch
spontaneous depolarization of a motor neuron (and all fibers)
benign - no co-morbidities
pathologic - w/co-morbidities 
quick twitch

Question 21

myoclonus

Answer 21

whole body jerk

Question 22

fibrillations

Answer 22

one m fiber spontaneous depolarization
always pathologic
denervated

Question 23

Tremors

Answer 23

oscillating movements

Question 24

Signs of LMN lesions - damage to A-Alpha

Answer 24

trauma -sharp
infection - polio - kills cell body in horn
degenerative disorder - ALS - glutamate excitotoxicity
vascular - compromise of Vv supply
tumor (trauma) - peripheral tumors grow on and press N

Question 25

hypotonic

Answer 25

loss of some a-alpha - spinal N

Question 26

flaccidity

Answer 26

loss of all m tone -peripheral N

Question 27

“flaccid paralysis”

Answer 27

loss of m tone and inability to contract