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Neuroscience > Motor Terms > Flashcards

Motor Terms Flashcards

1
Q

Alpha-Gamma Co-activation

A

Simultaneous firing of alpha and gamma motor neurons

- ensures that the m spindle maintains its sensitivity even when the extrafusal fibers surrounding the spindle contract

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2
Q

Alpha motor neurons

A

lower motor neurons that innervate extrafusal fibers in skeletal muscles
- when these neurons fire –> skeletal muscle contract

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3
Q

Amyotrophic lateral sclerosis

A

a disease that destroys only the lateral activating pathways and anterior horn cells in the SC, thus producing supper and lower motor neuron signals

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4
Q

Babinski’s sign

A

reflexive extension of great toe, often accompanied by fanning of the other toes
- the sign is elicited by firm stroking of the lateral sole of the foot, from the heel to the ball of the foot, then across the ball of the foot

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5
Q

Ceruleospinal Tract

A

Axons originating in the locus ceruleus that enhance activity in spinal interneurons and motor neurons

  • the effects of the ceruleospinal activity are generalized (not related to specific mov’ts)
  • other ceruleospinal neurons inhibit the nociceptive pathway neurons in the dorsal horn
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6
Q

Clasp-knife response

A

When a spastic muscle is slowly and passively stretched, resistence to stretch is suddenly inhibited at a specific point in the ROM

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7
Q

Clonus

A

Repetitive stretch reflexes elicited by passive dorsiflexion of the foot or passive extension of the wrist
- occurs in upper motor neuron lesions, secondary to the loss or alteration of descending motor control

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8
Q

Cocontraction

A

Simultaneous contraction of agonist and antagonist muscles

- may occur in an intact NS when learning a new mov’t or may be a sign of neural dysfunction

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9
Q

Control Circuits

A

Neural connections that adjust activity in the descending tracts

  • result in excitation or inhibition of the lower motor neurons
  • consist of the basal ganglia and cerebellum
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10
Q

Corticobulbar Fibers

A

Axons that influence the activity of lower motor neurons innervating the muscles of the face, tongue, pharynx, larynx
- corticobulbar fibers arise in motor planning areas of the cerebral cortex and the primary motor cortex, then project to CN nuclei in the brainstem

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11
Q

Cramp

A

Severe and painful muscle spasm associated with fatigue or local ionic imbalances

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12
Q

Descending motor tracts

A

Axons that convey mov’t-related info from the brain to lower motor neurons in the SC or BS

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13
Q

Disuse Atrophy

A

loss of muscle bulk resulting from lack of use

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14
Q

Fasciculation

A

A quick twitch of muscle fibers in a single motor unit, which is visible of the surface of the skin

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15
Q

Fibrillation

A

Brief contraction of a single muscle fiber, not visible on the surface of the skin

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16
Q

Fine Mov’t Tracts

A

Axons involved in the descending control of skilled, voluntary mov’t

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17
Q

Flaccid Paralysis

A

loss of voluntary mov’t and muscle tone

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18
Q

Fractionation

A

Ability to activate individual muscles independently of other muscles

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19
Q

Gamma motor neurons

A

lower motor neurons that innervate intrafusal fibers in skeletal muscle
- when the neurons fire, the ends of intrafusal fibers contract, stretching the central region of muscle fibers within the muscle spindle

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20
Q

Stepping Pattern Generator

A

A flexible network of interneurons that activate repetitive, rhythmical, reciprocal mov’t in the lower limbs, similar to stepping during walking

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21
Q

H-reflex

A

reflexive muscle contraction elicited by electrically stimulating the skin over a peripheral nerve
- used to assess the degree of excitation of alpha motor neurons

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22
Q

Hemiplegia

A

weakness or paralysis affecting one side of the body

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23
Q

Hyperreflexia

A

Excessive phasic and/or tonic stretch reflex response

  • often contributes to mov’t disorders after SC injury and in spastic CP
  • usually does not interfere with active mov’t after a stroke
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24
Q

Hypertonia

A

Abnormally strong resistance to passive stretch

  • occurs in chronic upper motor neuron disorders and in some basal ganglia disorders
  • Two types:
    1) Spastic = resistance depends on velocity of stretch
    2) Rigid = resistance is independent of velocity of muscle stretch
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25
Q

Lateral Activation System

A

Upper motor neurons that influence the activity of lower motor neurons innervating limb muscles
- includes the lateral corticospinal, rubrospinal, lateral reticulospinal tracts

26
Q

lateral corticospinal tract

A

Axons that arise in motor planning areas of the cerebral cortex and the primary motor cortex and synapse with lower motor neurons that innervate limb muscles
- essential for fractionated hand mov’ts

27
Q

Lateral premotor area

A

A region of the cerebral cortex involved in preparing for mov’t and controlling trunk/girdle muscles via the medial activation system
- located anterior to the UB region of the primary motor cortex, on the lateral surface of the hemisphere

28
Q

Lateral (medullary) reticulospinal tract

A

Axons originating in the medullary reticular formation that descend bilaterally to facilitate flexor muscle motor neurons and to inhibit extensor muscle motor neurons

29
Q

Lateral vestibulospinal tract

A

axons arising in the lateral vestibular nucleus that project ipsilaterally to facilitate lower motor neurons to extensor muscles and simultaneously inhibit lower motor neurons to flexor muscles via interneurons

30
Q

Lower Motor Neurons

A

neurons with their cell bodies in the SC or BS whose axons directly innervate skeletal muscle fibers
Two types:
1) alpha motor neurons innervate extrafusal muscle fibers
2) gamma motor neurons innervate intrafusal muscle fibers

31
Q

Medial Activation System

A

Upper motor neurons that influence the activity of lower motor neurons innervating postural and girdle muscles

32
Q

Medial Corticospinal Tract

A

Axons that convey information from motor areas of the cerebral cortex to the spinal cord
- the axons end in the cervical and thoracic cord and influence the activity of lower motor neurons that innervate neck, shoulder, trunk muscles

33
Q

Medial Reticulospinal Tract

A

Axons that project from the pontine reticular formation to the spinal cord
- activation of this tract facilitates ipsilateral lower motor neurons innervating postural muscles and limb extensors

34
Q

Medial Vestibulospinal Tract

A

axons arising in the medial vestibular nucleus that project bilaterally to the cervical and thoracic SC
- affect the activity of lower motor neurons controlling neck and upper back muscles

35
Q

Motor Unit

A

Alpha motor neuron and the muscle fibers it innervates

36
Q

Muscle Contracture

A

Adaptive shortening of muscle, caused by the muscle remaining in a shortened position for prolonged periods of time
- the decrease in length is caused by loss of sarcomeres

37
Q

Muscle Hyperstiffness

A

Excessive resistance to muscle stretch, regardless of whether the stretch is active or passive

  • produced by:
    1) neutral input to muscles (active m contraction) and/or
    2) changes within the muscle (myoplastic hyperstiffness, contracture, selective atrophy of specific m fiber types, weak actin-myosin bonding)
38
Q

Muscle spasm

A

sudden, involuntary contraction of muscle fibers

39
Q

Muscle tone

A

amount of resistance to passive stretch exerted by a resting muscle

40
Q

Myoplastic Hyperstiffness

A

excessive resistance to muscle stretch as a result of changes within the muscle secondary to upper motor neuron lesion

  • produced by contracture and increased weak actin-myosin bonding
  • after stroke selective atrophy of type II muscle fibers also contributes to the excessive resistance
41
Q

Neurogenic Atrophy

A

loss of muscle bulk resulting from damage to NS

42
Q

Neuromuscular Junction

A

Synapse bw a nerve terminal and the membrane of a muscle fiber
- ACh is the NT released at the neuromuscular junction

43
Q

Nonspecific activating tracts

A

UMNs that influence the general level of activity in LMNs

44
Q

Paralysis

A

Inability to voluntarily contract mm

  • reflexive contraction may be intact if the paralysis is due to an UMN lesion
  • reflexive contraction is absent if paralysis is due to a complete LMN lesion
45
Q

Paraplegia

A

Paresis or paralysis of both lower limbs

- may also involve part of the trunk

46
Q

Paresis

A

weakness

- decreased ability to generate the amount of force required for a task

47
Q

Phasic stretch reflex

A

Muscle contraction in response to quick stretch

Syn. myotatic reflex, m stretch reflex, deep tendon reflex

48
Q

Postural-gross mov’t tracts

A

Control automatic skeletal muscle activity

49
Q

Raphespiinal Tract

A

1) Axons originating in the raphe nuclei that enhance activity in spinal interneurons and motor neurons
* effects of raphespinal activity activity are generalized, not related to specific mov’ts
2) Axons originating in the raphe nuclei that inhibit the transmission of nociceptive info in the SC

50
Q

Reciprocal Inhibition

A

Decreased activity in an antagonist when an agonist is active

51
Q

Reflex

A

an involuntary response to an external stimulus

52
Q

Response Reversal

A

Modification of ongoing motor activity to adapt the mov’t to environmental conditions
- ex. catches foot under an object while walking –> foot moves to clear object instead of colliding with the object

53
Q

Rubrospinal Tract

A

Axons that originate in the red nucleus (midbrain) cross to opposite side, then descend to synapse with LMNs primarily innervating upper limb flexor mm

54
Q

Spasticity

A

1) Velocity-dependent m hypertonia

2) entire UMN syndrome

55
Q

Stroke

A

Sudden onset of neurological deficits caused by diruption of blood suplly in the brain
syn. CVA, brain attack

56
Q

Supplementary Motor Area

A

A region of the cerebral cortex involved in… 1) preparing for mov’t

2) orientation of eyes/head
3) planning bimanual and sequential mov’t
* located anterior to lower body region of the primary cortex, on the superior/medial surface of the hemisphere

57
Q

Tectospinal Tract

A

Axons that project from the superior colliculus to synapse with LMNs in the C-SC
- involved in reflexive mov’ts of the head toward stimuli

58
Q

Tendon Organ Reflex

A

Pressure on Golgi tendon organs activates neurons that inhibit the alpha motor neurons to the muscle associated with the stretched tendon

59
Q

Tetraplegia

A

Impairment of arm, trunk, lower limb, pelvic organ function

- usually result of damage involving cervical spinal cord

60
Q

Upper Motor Neurons

UMNs

A

neurons whose axons are located in a descending pathway

  • UMNs transmit info from the brain to LMNs and mov’t related interneurons in the SC or BS
  • Do not directly innervate skeletal m
  • Contribute to control of mov’t by influencing the activity of LMNs
61
Q

Withdrawal Reflex

A

Mov’t of a limb away from a stimulus

Neuroscience (13 decks)

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