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Motor Terms Flashcards

(61 cards)

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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
Lateral Activation System
Upper motor neurons that influence the activity of lower motor neurons innervating limb muscles - includes the lateral corticospinal, rubrospinal, lateral reticulospinal tracts
26
lateral corticospinal tract
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
Lateral premotor area
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
Lateral (medullary) reticulospinal tract
Axons originating in the medullary reticular formation that descend bilaterally to facilitate flexor muscle motor neurons and to inhibit extensor muscle motor neurons
29
Lateral vestibulospinal tract
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
Lower Motor Neurons
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
Medial Activation System
Upper motor neurons that influence the activity of lower motor neurons innervating postural and girdle muscles
32
Medial Corticospinal Tract
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
Medial Reticulospinal Tract
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
Medial Vestibulospinal Tract
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
Motor Unit
Alpha motor neuron and the muscle fibers it innervates
36
Muscle Contracture
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
Muscle Hyperstiffness
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
Muscle spasm
sudden, involuntary contraction of muscle fibers
39
Muscle tone
amount of resistance to passive stretch exerted by a resting muscle
40
Myoplastic Hyperstiffness
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
Neurogenic Atrophy
loss of muscle bulk resulting from damage to NS
42
Neuromuscular Junction
Synapse bw a nerve terminal and the membrane of a muscle fiber - ACh is the NT released at the neuromuscular junction
43
Nonspecific activating tracts
UMNs that influence the general level of activity in LMNs
44
Paralysis
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
Paraplegia
Paresis or paralysis of both lower limbs | - may also involve part of the trunk
46
Paresis
weakness | - decreased ability to generate the amount of force required for a task
47
Phasic stretch reflex
Muscle contraction in response to quick stretch | Syn. myotatic reflex, m stretch reflex, deep tendon reflex
48
Postural-gross mov't tracts
Control automatic skeletal muscle activity
49
Raphespiinal Tract
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
Reciprocal Inhibition
Decreased activity in an antagonist when an agonist is active
51
Reflex
an involuntary response to an external stimulus
52
Response Reversal
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
Rubrospinal Tract
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
Spasticity
1) Velocity-dependent m hypertonia | 2) entire UMN syndrome
55
Stroke
Sudden onset of neurological deficits caused by diruption of blood suplly in the brain syn. CVA, brain attack
56
Supplementary Motor Area
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
Tectospinal Tract
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
Tendon Organ Reflex
Pressure on Golgi tendon organs activates neurons that inhibit the alpha motor neurons to the muscle associated with the stretched tendon
59
Tetraplegia
Impairment of arm, trunk, lower limb, pelvic organ function | - usually result of damage involving cervical spinal cord
60
Upper Motor Neurons | UMNs
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
Withdrawal Reflex
Mov't of a limb away from a stimulus

Neuroscience (13 decks)

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