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spinal reflexes Flashcards

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1
Q

name the three types of movement classifications

A
  1. simple reflexes
  2. rhythmic motor patterns
  3. voluntary
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2
Q

what are examples of simple reflex types (generalised)

A

involuntary
rapid
stereotyped

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3
Q

what are examples of rhythmic motor patterns

A

combines voluntary + reflexive acts - walking, running, chewing
once initiated they are reflexive

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4
Q

what are examples of voluntary actions

A

complex- reading, writing
learned + purposeful

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5
Q

what three horns make up the grey matter of the spinal cord

A

dorsal horn
lateral horn
ventral horn

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6
Q

is the dorsal horn or ventral horn on the anterior side

A

ventral horn

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7
Q

does the dorsal root have a ganglion?

A

yes

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8
Q

which is responsible for flexion - the dorsal nerves or ventral nerves

A

dorsal

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9
Q

which is responsible for extension - the dorsal nerves or ventral nerves

A

ventral

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10
Q

what are Renshaw cells

A

interneurons involved in recurrent or feedback inhibition
-suppress weakly firing motor neurons
-dampens strongly firing ones to produce economical movement

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11
Q

what is the muscle spindle involved in (what is its role)

A

it identifies stretch
doesnt allow muscle to overstretch

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12
Q

what happens if a muscle stretches too far

A

gets damaged

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13
Q

how is the muscle spindle involved in proprioception

A

muscle spindle understands length of muscle and sends it to CNS so you know where limbs are at all times

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14
Q

what do afferent axons do

A

identify length and rate of stretch

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15
Q

what do gamma motor neurons do

A

modify set point of muscle spindle - change length not force!

sends it to spinal cord

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16
Q

what type of reflex is a myotatic (knee jerk) reflex

A

monosynaptic stretch reflex

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17
Q

what is a myotatic reflex

A

knee jerk reflex

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18
Q

what is the name of the afferent neuron involved in myotatic reflex (reflex)

A

la afferent

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19
Q

describe the pathway of a myotatic reflex (knee jerk) - there are 4 steps

A
  • tap of patellar tendon stretches quadriceps muscle
  • stimulates dynamic nuclear bag receptors of muscle spindle
  • increases rate of firing of la afferent leads to contraction of quadriceps muscle
  • la fibers also stimulate inhibitory interneurons which inhibits antagonistic (flexor) muscles of knee joint
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20
Q

the knee jerk reflex is lost if ______ are damaged

A

lower lumbar dorsal roots of spinal cord are damaged

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21
Q

what direction do reflexes travel through the spinal cord

A

in through the ganglion into the dorsal root, through into the ventral root

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22
Q

what are the two phases in the gait cycle?

A

right stance phase
right swing phase

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23
Q

what happens during the stance phase

A

foot touches the ground, flexion of knee and ankle
finishes with extension of all joints ready for forward movement

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24
Q

what happens during the swing phase

A

flexion of hip, knee + ankle
then knee and ankle extend

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25
what is the definition of a central pattern generator
use lots of reflexes together to run in a repetitive motion
26
how are central pattern generators modulated
via proprioceptive input
27
is the central pattern generator capable of autonomous signals
yes
28
where is the central pattern generator initated
in the mesencephalic locomotor region
29
what does the output leave the central pattern generator through
reticular nuclei reticulospinal tracts
30
as a muscle extends, what does the muscle spindle inhibit
flexor muscles
31
in the central pattern generator describe the pathway how flexor muscles are activated, starting from la afferent nerve
la afferent brings information from dorsal column to central pattern generator activates the flexor MN pool then the la inhibitory interneuron inhibits the extensor MN pool (crosses the ventral spinocerebellar tract) .. also renshaw cells provide negative feedback, inhibit the flexor MN pool and extensor MN pool then impulse travels to flexor muscles via dorsal column
32
in the central pattern generator describe the pathway how extensor muscles are activated, starting from la afferent nerve
la afferent brings information from dorsal column to central pattern generator activates the extensor MN pool then the la inhibitory interneuron inhibits the flexor MN pool (crosses the ventral spinocerebellar tract) .. also renshaw cells provide negative feedback, inhibit the extensor MN pool and flexor MN pool then impulse travels to extensor muscles via dorsal column
33
does the primary motor cortex (M1) supply muscles from the same side, opposite side, or both sides of the body
opposite side of the body
34
what are the names of the 4 premotor cortical areas
- supplementary motor area (SMA) - cingulate gyrus - ventral premotor cortex - dorsal premotor cortex
35
does the supplementary motor area (one of the 4 premotor cortical areas) supply muscles from one or both sides of the body
both
36
where does the basal ganglia receive excitatory input from
cerebral cortex
37
where does the basal ganglia outputs go to
thalamus spinal cord cerebral cortex
38
name the 5 parts of the basal ganglia
caudate globus pallidus subthalamic nucleus substantia nigra putamen
39
what is the hyperdirect pathway - there are 4 steps
initial planned info from motor cortex → subthalamic nuclei → globus pallidus → inhibits thalamus to allow initiation of movement to occur
40
describe the direct pathway
the striatum inhibits 1) the INTERNAL segment of globus pallidus 2) pars reticulata of substantia nigra substantia nigra inhibits thalamus thalamus stimulates motor cortex !!! OVERALL input is EXCITATORY
41
describe the indirect pathway
striatum inhibits the EXTERNAL segment of globus pallidus + subthalamic nucleus subthalamic nucleus projects excitatory input to internal segment of globus pallidus, pars reticulata of substantia nigra -> the thalamus is inhibited thalamus gives excitatory input to motor cortex !!! OVERALL input is INHIBITORY
42
what does the cerebellum do - what is its role
adjusts motor responses by comparing the intended output with sensory signals and to update movement commands if they deviate from the intended trajectory
43
where does the cerebrocerebellum get its info from and what does it control
receives input from cerebral cortex, movement planning and initiation of movement
44
where does the spinocerebellum get its info from and what does it control
receives input from the spinal cord about limb position, touch and pressure
45
what does the vestibulocerebellum control
balance and eye movements
46
what are the 3 peduncles names
superior middle inferior ---- peduncles
47
the superior peduncle connects the ________ to the ________
the superior peduncle connects the CEREBELLUM to the MIDBRAIN
48
what do the cerebellar peduncles all contain
efferent and afferent axons between cerebellum and CNS
49
the middle peduncle connects the ________ to the ________
the middle peduncle connects the CEREBELLUM to the PONS
50
the inferior peduncle connects the ________ to the ________
the inferior peduncle connects the CEREBELLUM to the MEDULLA
51
the majority of afferent signals use which two peduncles for passage
middle and inferior peduncles
52
the majority of efferent signals use which peduncles for passage
superior peduncle
53
what is an afferent neuron
bring sensory info from the outside world to the brain
54
what is an efferent neuron
carries signals from the brain to the PNS to initiate an action
55
where do all descending motor pathways originate (except the corticospinal tract)
brain stem
56
what are the 3 types of nuclei for postural control and locomotion
- vestibular nuclei - red nucleus - reticular nuclei
57
what are the names of the 5 brain areas that give rise to descending tracts
cerebral cortex brainstem + medulla --- reticular formation --- vestibular nuclei --- red nucleus --- tectum
58
what descending tract does the cerebral cortex give rise to
the corticospinal tract
59
in the brainstem + medulla, what descending tracts do: --- reticular formation --- vestibular nuclei --- red nucleus --- tectum give rise to. (there is 1 for each bullet point)
1. reticular formation reticulospinal 2. vestibular nuclei vestibulospinal 3. red nucleus rubrospinal 4. tectum tectospinal
60
muscle motor pathway lesion what is it involved in and what change occurs if it goes wrong
- normal reflexes - weakness/wasting eg - myositis, muscular dystrophy
61
neuromuscular junction (motor pathway lesion) what is it involved in and what change occurs if it goes wrong
- normal reflexes - normal muscle bulk - fatigable weakness eg - myasthenia gravis
62
how are upper motor neurons most likely to be damaged
cerebral vascular accident, spinal cord trauma
63
how are lower motor neurons most likely to be damaged
motor neurone disease, neuropathy
64
cerebellum (motor pathway lesion) what is it involved in and what change occurs if it goes wrong
normal reflexes, strength, - slight decrease in tone -incoordination, multiple sclerosis
65
basal ganglia (motor pathway lesion) what is it involved in and what change occurs if it goes wrong
movement changes - parkinson's, huntington's

physiology (10 decks)

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