Module 3 Lecture 1 Flashcards
(94 cards)
1
Q
___________ controls the vast majority of skeletal muscles
A
Spinal cord
2
Q
_____________ controls neck and arm region
A
Cervical
3
Q
_____________ controls the torso and leg
A
thoracic
4
Q
________________ has pelvic control
A
lumbar and sacral
5
Q
___________ controls and plans our movement
A
Motor cortex
6
Q
______________ areas of the brain do not generate movements they smooth movements
A
coordinating areas
ex- basal ganglia, cerebellum, the visual system
7
Q
_____________is how the brain organizes auditory information
A
auditory system
8
Q
Consists of all the muscles and the neurons
that control them
A
motor system
9
Q
• The motor control comes from
A
– The spinal cord (programs)
– The brain
10
Q
• Somatic motor system
A
– Skeletal muscles (33 somites)
– Nervous system controls them
– Voluntary
11
Q
It was widely accepted
that reflexes occurred as
isolated activity within a _________________
A
a reflex arc
12
Q
Reflexes are ___________
A
integrative activities
13
Q
\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ shared the Nobel prize with Edgar Adrian in 1932 for their discoveries regarding the functions of neurons
A
Sir Charles Scott Sherrington
(1857-1952)
The Sherrington’s law
14
Q
The brain commands and control the _________________
A
motor programs in the spinal cord.
15
Q
______________
– Muscles of the trunk
– To maintain posture
A
• Axial muscles
16
Q
_____________
– Muscles of the shoulders, elbows, thighs, and knees
– Locomotion
A
• Proximal muscles
17
Q
________________
– Muscles of the hands, feet, and digits
– Manipulations of objects
A
• Distal muscles
18
Q
__________________Innervated by alpha motor neurons
Roots form mixed spinal nerves
A
skeletal muscles
19
Q
How many spinal nerves are there
A
31 nerves
20
Q
C1-8: _______________
A
spinal nerves
21
Q
T1-12: ___________
A
thoracic nerves
22
Q
L1-5:_________________
A
Lumbar nerves
23
Q
S1-5:___________________
A
sacral nerves
24
Q
1:_____________________
A
coccygeal
25
C3-T1
| Innervate _______________
about
| 50 muscles
26
Motor neurons that innervate the proximal and distal muscles are found mainly
in the cervical and lumbar-sacral segment.
27
Neurons innervating the
| axial muscle are medial to
to those innervating the
| appendicular
28
Neurons innervating flexors are dorsal to
| those
innervating extensors
29
Lower Motor Neurons
* Alpha motor neurons
| * Gamma motor neurons
30
• Typical motor neurons that innervate the muscle
| cells
Alpha Motor Neurons
31
What are the three types of inputs to alpha motor neurons
1. input from upper motor neurons in the brain
2. sensory input from muscle spindles
3. input from spinal neurons
32
Sir Charles Scott Sherrington
| When a muscle is stretched, it __________
tends to contract
33
_____________ are traditional muscles
extrafusal
34
___________ are special sensory muscles
intrafusal
35
__________ a group of muscle fibers which are innervated by unique nerves
muscle spindle
36
______________ wrap around the
| muscle fibers of the spindle in the middle
Group Ia sensory axons wrap
37
_____________ stops the muscle from over stretching. Over stretching prevents the cross bridge cycle from working
muscle spindle
38
over stretching prevents the
cross bridge cycle from working
39
_______________ never stop firing because their function is to relay length information
1a motor neurons
40
Muscle spindles provide protection against overstretching because of ___________________________
1a sensory neurons which innervate alpha neurons causing contraction
41
What happens when you put weight on a muscle and the muscle lengthens
1A sensory neurons fire more than normal and they tell alpha motor neuron to control mechanism of firing
42
what makes 1a axons fast firing
more myelination and wider diameter
43
```
Group Ia Axons
• Thickest myelin
• Enter via the _______________
• Synapse with _____________
– Lots of synapses
```
dorsal root
interneurons and alpha motor
neurons
44
____________ gated channels on the 1A sensory motor neurons
stretch gated channels
| -works when membrane is stretched open causing depolarization and action potentials
45
give an example of muscle mechano receptors
the knee jerk reflex. When tapping the tendon, the muscle briefly stretches
46
muscle spindles are inside the muscle and thus have specific
origin and insertion
47
When alpha motor neurons innervate the
extrafusal muscles, the _________.
As a result, the spindle becomes _________
The Ia sensory, will ________________
muscle contracts
slack (not stretched)-
not send a signal anymore
48
• Gamma MNs innervate___________________
specialized muscle fibers
| within the spindle called intrafusal muscle fibers
49
__________________are located at the two ends of the
| spindle
Gamma MNs
50
```
Feedback Loop (Homeostasis)
• Control center:
– Set point:_____________
• Receptor: __________
• Effector: __________________________
```
a desired muscle length
Ia axons
alpha motor neurons and extrafusal fibers
51
Gamma Loop
• The gamma MN activity influences ________________________ if we are outside the
set point
the alpha motor neuron activities
52
• During most normal movements, alpha and
| gamma motor neurons are
simultaneously
| activated
53
________ controls th homeostasis loop
cerebellum
54
___________ when the muscle spindle is not parallel to extrafusal muscle. Brain is not sure about what is going on
hypotonia
55
___________
– Fiber is 50-100 um wide
– Fiber is 2-6 cm long
– Muscle has 103 – 109 fibers
– Muscle is controlled by about 100 alpha motor
neurons
– Alpha motor neuron innervates about 100-1000
muscle fibers
– A muscle fiber is innervated by only one alpha
motor neuron
• Extrafusal
56
```
________________
– Known as muscle spindles
– Embedded in the extrafusal fibers
– A spindle consists of 8-12 muscle fibers
– Sensory axon wraps around them
– Continuously monitors length of muscle
– Used for feedback control of movement
– Innervated by gamma motor neuron
```
Intrafusal
57
When Do We Use the Ia Sensory?
always
58
when are the 1a sensory so valuable
- in extreme situations
| - tight rope walking and extreme balance
59
what is the formula for gain
contraction/ stretching
60
Shared the Nobel prize with Cajal in 1906 in recognition
| of their work on the structure of the nervous system
camillo Golgi
61
Golgi tendon organs:
| When the muscle contracts, the_____________ fire action potential
sensory 1b axons
62
____________ is located in the tendon of the insertion muscle
Golgi tendon organ
63
The Ib sensory neuron may protect the muscle from being _____________
However, its normal function is to ________________
overloaded.
| regulate muscle tension within an optimal range.
64
The 1b axons do not communicated directly with the alpha Motor neurons, it goes through ______________
an inhibitory neuron
65
Scottish surgeon and artist Charles Bell
| showing a man in the throes of tetanus caused by
bacteria in the inhibitory neurons
66
activity of muscle spinal has nothing to do with the activity of
Golgi tendon
67
muscle spindle located in __________ to extra fusal muscles
series
68
Golgi tendon located in __________ to extra fusal muscle
parallel
69
What are the three Inputs to Alpha Motor Neurons:
| Interneurons
1. Upper motor neurons in brain
2. sensory input from muscle spindles
3. input from spinal neurons
70
Most of the innervation to the alpha motor
| neurons comes from _______________
interneurons of the spinal
| cord
71
Spinal interneurons receive inputs from
| (3 places)
– Primary sensory axons
– Descending axons from the brain
– Collaterals of lower motor neurons axons
72
• Spinal neurons can form
– Inhibitory synapses
| – Excitatory synapses
73
Spinal neurons can form
–_____________ (reciprocal inhibition)
–____________ (flexor withdrawal reflex and
cross extensor reflex)
inhibitory
| excitatory
74
Flexor reflex
| – Its speed depends on how ___________
painful the stimulus is
75
flexor reflex:
– The direction of the reflex depends on the
______________
location of the stimulus
76
flexor reflex:
| – Slower than the ___________
stretch reflex
77
flexor reflex
– Activated by Aδ nociceptive axons that enter the
spinal cord and branch profusely and enter
_______________
different segment of the spinal cord
78
• Flexor reflex
– Nociceptive axons act on excitatory interneurons
that excite alpha motor neurons of ____________________
the flexors of the affected limb
79
flexor reflex
– At the same time, they activate the inhibitory
interneurons that synapse on the ______________
alpha motor
| neurons of the extensors
80
___________ activates the same muscle intending to move
muscle tendon
81
_________ activates the opposite muscle intended to move
Golgi tendon
82
Aδ nociceptive axons __________
branch profusely
83
reflexes are helpful in
motor skills
84
• Root reflex: corner of the mouth
helpful for breast feeding
85
• Babinski reflex is the
toe fanning of a baby
86
The cross extensor reflex is the building block
| for ____________
locomotion
87
Local circuits within the spinal cord
– Central pattern generator
– Neurons with pacemaker properties
– Able to control the timing and coordination
88
In bipeds, the movement of a single limb is a
| cycle of _____________
two phases
89
Phase I:____________
• Limb is extended in contact with the ground to propel
forward
stance phase
90
Phase II: ___________
| Limb is flexed to leave the ground and brought forward
swing phase
91
Locomotion is accomplished by ___________
higher centers
| in the brain
92
```
Decerebrate prep: spinal
cord and brain stem
isolated by cut at “a”
Animal can still walk on a
treadmill
```
Spinal prep: cut at “b”
isolates hind limb spinal
segments yet animal can
still walk on a treadmil
Deafferented prep: yet
animal can still walk on a
treadmil
Conclusion
In conclusion, locomotion
– Is not dependent on sensory input
– Not dependent entirely on higher centers in the
brain
– It is dependent on spinal cord neurons that exhibit
a central pattern generator rhythm
93
_________
- work on their own
- have their own action potentials
central pattern generators
94
compare cpg vs reflex
CPG: does not rely on sensory information as much
Reflex: rely on sensory information
