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Flashcards in Motor Control - Reflexes Deck (65)
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1

Placing reaction and hopping reaction are examples of

cortical reflexes

2

Stretch (myotactic), golgi tendon, and crossed extensor ar examples of

spinal reflexes

3

vestibular, righting, suckle, yawn, eye/head movements are examples of

Brainstem/midbrain reflexes

4

Reflexes in oder to be effective must be very precise. This "precision" can

make reflexes look like volitional movement

5

difference between reflex and volitional movement

a reflex movement occurs faster than the fastest voluntary motion

6

reflex activity characteristics

precis motions in response to afferent stimuli
mediated at all levels of the CNS
rapid initiation
many elicited even during unconsciousneess

7

volitional activity characteristics

originates in cortical areas associated with judgement, initiative, and motor control
longer onset, latency due to processing
require conscious awareness

8

myotactic reflex (stretch) - appearance

shortening/contraction of a stretched muscle

9

myotactic reflex - purpose

protect mm from tearing due to strain

10

myotactic reflex - characteristics

initiated by muscle spindle
monosynaptic, segmental reflex

11

the muscle spindle is ____ to extra fusel fibers

parallel

12

There are ______ types of fibers with in the muscle____

several
spindle

13

muscle contains _____ and _____ parts

afferent (sensory)
efferent (muscle)

14

intrafual fibers of the muscle spindle have _______ components

both motor and sensory

15

Characeristics of the sensory fiber of a muscle spindle

not contractile
it's the portion sensitive to length
two sensors with different afferents
1. nuclear bag fiber
2. nuclear chain fiber

16

Primary afferent of myotactic reflex

1a fiber

17

characteristics of 1a fiber

large, myelinated
sensitive to both length of mm and how fast that length is changing

18

1a fiber innervates

nuclear bag and nuclear change

19

at resting lenth, the 1a fiber fires

less frequently

20

with stretch, the 1a fiber fires

more frequently

21

with fast stretch, the 1a fiber fires

most frequently

22

The secondary afferent is a ____ fiber

Group II fiber

23

secondary afferent characteristics

smaller, myelinated,
sensitive only to the length of the muscle

24

the secondary afferent innervates

only the nuclear chain

25

Primary Afferent associated with the muscle spindle - summary

large 1a fiber (heavily myelinated, fast velocity, low threshold)
innervates both nuclear bag and nuclear chain fiber
detects length and speed of change of length

26

Secondary Afferent associated with the muscle spindle - summary

group II fiber (smaller, less myelin, still pretty fast)
innervates nuclear chain only
detects only lenth

27

Motor portion of the muscle spindle consists of

intrafusal contractile elements

28

characteristics of motor portion of muscle spindle

same as skeletal muscle
control length of the sensory portion

29

motor portion of the muscle spindle innervated by

gamma motor neuron

30

By contracting intrafual muscles, we

stretch the sensory portion
this renders the sensory portion more sensitive to a superimposed stretch