Motor Systems: Spinal Cord and the Motor Unit Flashcards Preview

Integrative Neuroscience > Motor Systems: Spinal Cord and the Motor Unit > Flashcards

Flashcards in Motor Systems: Spinal Cord and the Motor Unit Deck (76):
1

Types of motor organs

Cilia
Glands
Muscles

2

Types of glands

endocrine
exocrine

3

Types of exocrine glands

internal
external

4

Types of muscles

smooth
striated

5

Types of smooth muscles

visceral
peripheral

6

Types of striated muscles

cardiac
skeletal

7

Motor Pools

Clusters of motor neurons in the spinal cord

8

Lower motor neurons reside in the _____ horn of the spinal cord.

ventral

9

Neurons that control the proximal muscles are located in the _____.

medial ventral horn

10

Neurons that control the distal muscles are located in the _____.

lateral ventral horn

11

Pathways in the medial part of the spinal cord control _____.

posture

12

Pathways in the lateral spinal cord control _____.

fine movements in extremities

13

Flexor and extensor muscles work together through _____.

complementary excitation and inhibition

14

Length change in _____ create the reflex negative feedback control mechanism.

muscle fibers

15

_____ innervate the extrafusal, force-producing fibers which control posture and movement.

alpha motor neurons

16

_____ innervate intrafusal muscle fibers (_____) to control tension on the receptors.

gamma motor neurons
muscle spindles

17

a single _____ innervates many muscle fibers.

alpha motor neurons

18

_____ spread force evenly across a muscle.

alpha motor neurons

19

Types of alpha motor neurons

fast fatigable
fast fatigue-resistant
slow

20

Fast fatigable alpha motor neurons are _____ and have a _____ threshold.

large
high

21

Fast fatigue-resistant alpha motor neurons are _____ and have a _____ threshold.

medium size
medium

22

Slow alpha motor neurons are _____ and have a _____ threshold.

small
low

23

Slow alpha motor neurons are mainly used for _____.

posture

24

Fast fatigable alpha motor neurons are used for _____.

generating a lot of force
(ex: running)

25

At higher frequencies, muscle fiber twitches _____.

summate

26

Higher force requirements recruit more and more _____.

neurons

27

Group Ia afferents - known as _____ - respond phasically to _____.

nuclear bag fibers
small stretches

28

Group II afferents fire tonically to signal _____.

degrees of sustained stretch

29

_____ help maintain posture and balance, allowing one to walk without consciously thinking about each step.

Monosynaptic stretch reflexes

30

Feed-forward inhibition enhances the effect of the _____ by suppressing the _____.

active pathway
opposing pathway

31

Activation of the _____ ensure that only the appropriate muscle gets activated.

inhibitory interneurons

32

Feed-back inhibition serves as a _____ to prevent _____.

self-regulating mechanism
over-excitation

33

_____ regulate excitability of muscle spindles.

gamma motor neurons

34

Mechanoreceptors in golgi tendon organs predominantly signal changes in _____.

muscle tension

35

Golgi tendon organs provide _____ via inhibitory interneurons in the spinal cord.

negative feedback

36

Painful esnsory stimulation leads to _____.

flexion reflex

37

Flexion reflex inhibits the _____ and activates the _____.

extensor
flexor

38

The flexion reflex is accompanied by the _____.

crossed extension reflex

39

The crossed extension reflex serves to _____ by activating the _____.

maintain posture/balance
opposite side

40

_____ are excited by collaterals from motor neurons and inhibit those same motor neurons.

Renshaw cells

41

Local circuit neurons in the intermediate zone of the spinal cord are _____.

topographically arranged

42

Upper motor neurons in the cortex reside in layer __ of the _____.

5
primary motor cortex

43

Betz-cells are _____ than pyramidal cells.

larger

44

Betz-cells are specific to _____.

layer 5 of the primary motor cortex

45

Layer 5 neurons from the primary motor cortex and premotor cortex form the _____.

pyramidal tract

46

The corticospinal and corticobulbar tracts intersect at the _____.

internal capsule (forebrain)

47

The pyramidal tract consists of the _____ and _____ tracts.

corticospinal
corticobulbar

48

The pyramidal tract first enters the midbrain through the _____.

cerebral peduncle

49

The pyramidal tracts projections through the _____ give its name.

meduallary pyramids

50

Corticobulbar projections of the pyramidal tract terminate only in the _____.

brainstem

51

The corticospinal projection innervates the _____.

spinal cord

52

__% of fibers in the cortical spinal tract form the lateral tract.

90

53

__% of fibers in the cortical spinal tract form the ventral tract.

10

54

_____ is the reason why a side of the brain controls the contralateral side of the body.

decussation

55

The corticobulbar tract terminates on motor neurons within the _____.

brainstem motor nuclei

56

The corticospinal tract controls _____.

spinal motor neurons

57

Pyramidal tract neurons innvervate multiple motor neurons that control _____.

multiple/different muscles
(maps of movement/coordination)

58

__% of axons in the corticospinal tract arise directly from the premotor cortex.

30

59

Activity of the _____ is related to motor planning, preparatory activity, and selection of a movement.

premotor cortex

60

_____ in the prefrontal cortex are responsible for understanding movements of others.

mirror neurons

61

Mirror neurons do not fire when an experimenter _____.

uses a tool

62

Mirror neurons encode _____.

intentions of self and others

63

Extrapyramidal tracts are responsible for _____.

involuntary reflexes, movement and it's modulation

64

Motor control of the brainstem controls _____, _____ and _____.

balance
posture
gaze

65

Feedforward mechanisms act through the _____ to predict resulting disturbances in stability and generate stabilizing responses.

reticulospinal pathway

66

Extrapyramidal tract projections terminate in the _____.

reticular formation

67

The reticulospinal pathway projects to motorneurons in the spinal cord that control _____ to stabilize posture.

axial and proximal muscles

68

The tectospinal pathway targets the _____.

tectum
(superior/inferior colliculus)

69

The reticulospinal pathway targets the _____.

pontine and medullary reticular formation

70

The vestibulospinal pathway targets the _____.

lateral and medial vestibular nuclei

71

The colliculospinal pathway from the superior colliculus controls _____ to orient _____.

neck muscles
head and eye movements

72

The reticulospinal pathway controls temporal and spatial coordination of _____.

limb and trunk movements

73

The vestibulospinal pathway controls _____.

reflex control of neck muscles (medial)

74

The vestibular nuclei receive inputs from cranial nerve __.

VIII
(inputs from semicircular canal and otolith organ)

75

The reticulospinal pathway integrates information from the motor systems to coordinate _____.

automatic movements of locomotion and posture

76

The reticulospinal pathway facilitates and inhibits _____ and influences _____.

voluntary movement
muscle tone