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Neurobiology > Hirsch - Spinal Motor > Flashcards

Hirsch - Spinal Motor Flashcards

(57 cards)

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1
Q

Eadweard Myubridge

A

Motion recording

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2
Q

Motor Pathways

A

Upper motor neurons in brainstem and cortex

Lower motor neurons in spinal cord

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3
Q

Spinal cord - know the locations in the picture

A 
Dorsal Horn
Dorsal roots
Lateral white matter
Ventral Horn
Ventral roots 
Medial white matter
  • grey matter (inside)
  • white matter (outside)
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4
Q

Dorsal Horn

A

inputs from sensory cells, cell bodies of local circuit neurons

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5
Q

Dorsal Roots

A

somas of sensory neurons

axons travel into the cord and out to sensory receptors = afferent

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6
Q

Lateral white matter

A

carries fibers from motor cortex

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7
Q

Ventral Horn

A

cell bodies of motor neuron

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8
Q

Ventral roots

A

axons of lower motor neurons that travel out towards muscles = efferent

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9
Q

medial white matter

A

carries fiber from brainstem

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10
Q

SAME-DAVE

A

sensory-afferent, motor-efferent

dorsal-afferent, ventral-efferent

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11
Q

Levels of spinal cord

A 
(from top )
cervical - arm movement
thoracic - information transfer
lumbar - leg movement
sacral
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12
Q

different types of fibers

A 
Dorsal roots (sensory afferents)
Ventral roots (motor efferents)

SAME-DAVE

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13
Q 
Dorsal Roots (sensory afferents)
SAME-DAVE
A 
muscle spindles
golgi tendon organs
tactile
sharp pain/temp
dull pain
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14
Q 
Ventral Roots (motor efferents)
SAME-DAVE
A

alpha-motorneuron -> larger

gamma-motorneuron -> small

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15
Q

Motor unit

A

group of muscle fiber that receive input from a single motor neuron
single action potential to many muscle fibers

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16
Q

Somatotopic arrangement of Lower Motor Neurons (Ventral horn)

A

motor neurons that innervate proximal muscles are central

motor neurons that innervate distal muscles are lateral

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17
Q

Different alpha- motor neurons

A

Smaller
Larger
Intermediate sized

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18
Q

Small alpha motor neuron

A

slow
muscle fibers that generate small but lasting contraction
180 muscle fibers per neuron (or smaller for eye movement)

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19
Q

larger alpha motor neuron

A

fast fatigue
generate larger forces - jumping
1-2K fibers; less precision, more power

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20
Q

Intermediate sized alpha motor neuron

A

fatigue resistant

intermediate properties

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21
Q

Motor pool

A

group of motor neurons that innervate a single muscle
can comprise more than one type of motor unit (slow, fast, intermediate..)
ex) calf muscle used for standing, jumping, walking …

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22
Q

Muscle spindle

A

each spindle contains intrafusal fibers arranged in parallel with the extrafusal muscle fibers

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23
Q

Nuclear bag

Study These Flashcards
A

response to rate of change (velocity)

24
Q

nuclear chain

Study These Flashcards
A

track muscle length

25
sensory afferents
Group Ia | Group II
26
Group Ia
sensory afferent wrap around the bag and chain fibers most active when stretching
27
Group II
sensory afferent wrap around the chain fiber only most active when stretched
28
intrafusal fibers
innervated by gamma-motor neurons
29
gamma-motor neuron
regulate the sensitivity of the muscle spindle | pulling at both ends of bag and chain fibers; stretching the regions where afferent endings are wrapped
30
Golgi tendon organs
1. capsules encasing Group Ib afferents * organs are embedded in the tendons that connect muscle to bone 2. signal information about force
31
Group Ib
wrap around collagen fibrils
32
afferent activity is greatest when...
the muscle contracts
33
muscle spindles and golgi tendon organs
(passive stretch) from short to long II sensitive to length Ia sensitive to velocity and length Ib not sensitive (passive stretch) from long to short II less sensitive to length Ia less sensitive to length; AP recorded from afferent Ib very sensitive
34
velocity and length of muscle
phasic - brief; velocity | tonic - longer; length
35
Monosynaptic stretch reflex
maintains muscle length | ex. classical reflex hammer to the knee
36
Know the picture of knee reflex in 13/22 slilde
agonist, antagonist, alpha motorneuron, inhibitory, Ia fiber
37
Knee reflex occuring steps
1. agonist muscle is stretched --> increase in discharge by Ia afferents 2. a. Discharge ---->> mono-synaptic excitation of alpha-motor neuron (white cell) in lateral horn which innervates same muscle to contract to restore muscle length 2. b. Discharge --->> di-synaptic relaxation of the antagonist; Ia afferent synapses with an inhibitory inter neuron in the dorsal horn --> suppresses activity in the alpha-motor neuron that innervates the antagonist
38
1a fibers and alpha fibers have
large diameters so conduct quickly; fast reflex
39
Golgi tendon organ reflex in knee reflex
it maintains tension via negative feedback 1. agonist contract 2. muscle tension increases 3. Ib afferents fire hard * Ib afferent synapses with an inhibitory interneuron 4. reduces firing of the alpha motor neuron 5. muscle relaxes, tension decreases
40
Top down control of spinal cord from cortex and brainstem 1. lateral white matter medial white matter
lateral white matter (know location) = axons from motor cortex medial white matter (know location) = axons from brainstem
41
Upper motor neurons reside where? 15/22
brainstem and cortex
42
Brainstem to spinal cord
* many things happen, but simply remember... brainstem nuclei provide upper motor neurons that project to the cord * * there are many tracts such as... (study their pictures 16/22) 1. lateral and medial vestibulospinal tracts 2. reticulospinal tract 3. colliculospinal tract
43
premotor cortex in frontal lobe
supplemenatary and premotor cortex = movement planning | *more to the frontal lobe
44
motor cortex in frontal lobe
movement execution | * further from frontal lobe
45
motor movement planning and execution
1. frontal lobe = idea 2. premotor cortex = program 3. supplementary motor area = program 4. primary motor cortex = execution
46
motor homunculus
at primary motor cortex corticobullbar tract = face corticospinal tract = upper extremity, trunk, lower extremity
47
histology of motor cortex
in primary motor cortex; Betz cells (large, fast conduction) and non-Betz pyramidal neurons exist
48
Betz cells
big; fast conduction axons form most fibers in descending tracts * descending tract = corticospinal tract, corticobulbar tract
49
descending tract in primary motor cortex
corticospinal tract | corticobulbar tract
50
corticospinal tract
to the spinal cord | upper motor neuron
51
corticobulbar tract
to the brainstem | upper motor neuron
52
Corticospinal tract
cortex -> midbrain -> middle pons -> middle medulla -> caudal medulla (pyramidal decussation; nerve crosses to opposite side) -> spinal cord * subdivision: lateral corticospinal (cross), anterior corticospinal (do not cross)
53
corticobulbar tract
cortex-> midbrain-> middle ons-> middle edulla (brain stem) | uncrossed
54
subdivision of corticospinal tract
later corticospinal | anterior corticospinal
55
later corticospinal tract
80% of cortico-spinal tract; distal muscles (fingers and toes) most fibers cross at pyramidal decussation in caudal medulla controls detailed/fine movement
56
anterior corticospinal tract
anterior or ventral crosses at the cord(?) bilateral & polysynaptic with medial motorneurons (maintain posture)
57
cells in motorcortex arranged in colums that perform common functions
motor cortex are believed to be organized according to movements (functions carried by muscles) rather than target muscle *

Neurobiology (11 decks)

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