Neurophysiology Test 2

Front 1

4. As you try to lift a heavy box, which type of motor unit do you recruit first and which do you recruit last, according to the size principle?

Back 1

a. When synaptic input to a motor pool increases, progressively larger motor units that generate larger forces are recruited. Thus, as synaptic activity driving a motor neuron pool increases, low threshold S motor units are recruited first, then FR motor units, and finally, at the highest levels of activity, the FF motor units. This systematic relationship has come to be known as the size principle.

Front 2

5. What prevents muscle spindles from being useless when their muscle contracts?

Back 2

a. In terms of engineering principles, the stretch reflex arc is a negative feedback loop used to maintain muscle length at a desired value. The appropriate muscle length is specified by the activity of descending upper motor neuron pathways that influence the lower motor neuron pool. Deviations from the desired length are detected by the muscle spindles, since increases or decreases in the stretch of intrafusal fibers alter the level of activity in the sensory axons that innervate the spindles. These changes lead, in turn, to adjustments in the activity of the α motor neurons, returning the muscle to the desired length by contracting the stretched muscle and relaxing the opposing muscle group, and by restoring the level of spindle activity to what it was before.
b. The smaller γ motor neurons control the functional characteristics of the muscle spindles by modulating their levels of excitability. When the muscle spindle is stretched, the spindle is also stretched and the rate o discharge in the afferent fibers in increased. When the muscle shortens, however, the spindle is relieved of tension, or “unloaded,” and the sensory axons that innervate the spindle might therefore be expected to fall silent during contraction. However, they remain active. The γ motor neurons terminate on the contractile poles of the intrafusal fibers, and the activation of these neurons causes intrafusal fiber contraction – in this way, maintaining the tension on the middle (or equatorial region) of the intrafusal fibers where the sensory axons terminate. Thus, co-activation of the α and γ motor neurons allows the spindles to function at all muscle lengths during movements and postural adjustments.

Front 3

MSO's measure mm ________ and ___________

Back 3

Velocity and length

Front 4

GTO's measure mm _______

Back 4

tension

Front 5

List the 3 sources of direct synaptic input to alpha motor nn:

Back 5

UMN, MSO, GTO

Front 6

Basal ganglia synapse at the ____________

Back 6

motor cortex

Front 7

Cerebellem synapses at the _______________

Back 7

brainstem centers

Front 8

A ____________ is an alpha motor nn and the mm fibers that it innervates.

Back 8

motor unit

Front 9

What is the order of motor units when lifting something heavy? This is known as the __________

Back 9

S > FR > FF

size principle

Front 10

What prevents mm spindles from being useless when their mm contracts?

Back 10

Gamma mm neurons make sure the MSO stretches/contracts in relation to mm

Front 11

The clasp knife reflex is increased resistance to ______________

Back 11

passive stretch

Front 12

____________ regulate locomotion such as walking , swimming, flying...rhythmic motions....adaptive such as speeding up treadmill

Back 12

Central pattern generators

Front 13

Would spinal cord transection inhibit central pattern generators?

Back 13

NO

Front 14

Are CPG's dependent on descending pathway input?

Back 14

NO

Front 15

a neurodegenerative disease that affects an estimated 0.05% of the population in the US and is characterized by the slow but inexorable degeneration of α motor neurons in the ventral horn of the spinal cord and brainstem (lower motor neurons), and of neurons in the motor cortex (upper motor neurons).

Back 15

ALS

Front 16

a group of structures embedded in the depths of the forebrain, that suppress unwanted movements and prepare (or “prime”) upper motor neuron circuits for the initiation of movements.

Back 16

Basal ganglia

Front 17

Weakness, spasticity, hypertonicity, hyperreactive deep reflexes, babinski sign, .......

Back 17

Upper motor neuron syndrome

Front 18

paresis, paralysis, decreased superficial reflex, hypoactive deep reflex, , fasciculation, fibrillations, and severe mm atrophy.........

Back 18

Lower motor neuron syndrome

Front 19

clonus,

Back 19

Upper motor neuron syndrome

Front 20

and loss of fine voluntary mvmts

Back 20

Upper motor neuron syndrome

Front 21

hypotonia

Back 21

Lower motor neuron syndrome

Front 22

babinski sign, .......

Back 22

Upper motor neuron syndrome

Front 23

fasciculation, fibrillations

Back 23

Lower motor neuron syndrome

Front 24

Medial spinal cord interneurons terminate ______ and are concerned with _______________.

Back 24

bilaterally

posture and balance

Front 25

Lateral spinal cord interneurons terminate _______ and are primarily concerned with _______________

Back 25

ipsilaterally

Fine mvmt of distal extremities

Front 26

The ___________are the major destination of the axons that form the vestibular division of the 8th cranial nerve; as such, they receive sensory information from the semicircular canals and the otolith organs that specifies the position and the angular and linear acceleration of the head.

Back 26

vestibular nuclei

Front 27

Where are the vestibular nuclei located?

Back 27

Midbrain

Front 28

What is the primary function of the vestibular nuclei > Vestibulospinal tract?

Back 28

regulates the head position by reflex actions of neck muscles in response to the stimulation of the head

Front 29

The ____________is responsible for the feed-forward mechanism that predicts the resulting disturbance in body stability and generates an appropriate stabilizing response.

Back 29

reticular formation

Front 30

The axons arising from neurons in deep layers of the superior colliculus project via the _______________to medial cell groups in the cervical cord, where they influence the lower motor neuron circuits that control axial musculature in the neck.

Back 30

colliculospinal tract

Front 31

What is the head's equivalent of the body's corticospinal tract?

Back 31

Corticobulbar tract

Front 32

What are the structures of the basal ganglia?

Back 32

Caudate

Putamen

Globus pallidus

Substantia Nigra pars reticulata

Front 33

________________ and ____________ are the inputs for the basal ganglia.

Back 33

Caudate and putamen

Front 34

______________ and ________________ are output for the basal ganglia.

Back 34

Globus pallidus

substatia nigra pars reticulata

Front 35

What is the general function of the basal ganglia?

Back 35

ensure that you are able to initiate mvmts when you want and stop spontaneous mvmts

Front 36

The ____________ and ___________ make up the corpus striatum.

Back 36

Caudate and Putamen

Front 37

What is the largest source of neural input to the basal ganglia?

Back 37

Cerebral cortex

Front 38

In Huntington’s disease, which neurons in the basal ganglia are the main ones that degenerate?

Back 38

medium spiny neurons that project to the external segment of the globus pallidus degenerate

Front 39

_____________ is the largest cerebellar subdivision; resides in the lateral cerebellar hemisphere; recieves input from cerebral cortex; used for highly skilled mvmts

Back 39

Cerebrocerebellum

Front 40

__________ = Caudal lobes of cerebellum; includes flocculus and the nodulus; recieves input from vestibular nuclei; posture and equilibrium

Back 40

Vestibulocerebellum

Front 41

_______________ = median and paramedian zone; mvmts of distal mm by lateral and mvmt of proximal by central; moves eyes in response to vestibular input

Back 41

Spinocerebellum

Front 42

Name the 3 cerebellar peduncles....

Back 42

superior

middle

inferior

Front 43

Efferent or Afferent????

Superior cerebellar peduncle

Middle cerebellar peduncle

Inferior cerebellar peduncle

Back 43

Superior cerebellar peduncle--almost entirely efferent

Middle cerebellar peduncle---Afferent

Inferior cerebellar peduncle---Mixed

Front 44

What is the largest source of input to the cerebellum?

Back 44

Cerebral cortex

Front 45

What is meant by fractured somatotopy in the cerebellum?

Back 45

Each area of the body is represented mx times in the cerebellum

Front 46

From where does the cerebellum recieve sensory input?

Back 46

Pontine nuclei

Inferior olive

Front 47

What type of nn provide output from the cerbellar cortex?

Back 47

purkinje

Front 48

Cerebellar output is entirely excitatory/inhibitory....uses what NT?

Back 48

Inhibitory

GABA

Front 49

Rapid ballistic mvmts fo the eyes that abruptly chane the point of fixation...???

Back 49

Saccade

Front 50

Is saccades voluntary or reflexive?

Back 50

Either

Front 51

Slow tracking mvmts of eyes designed to keep a moving stimulus in the fovea...????

Back 51

Smooth pursuit mvmts

Front 52

Are slow pursuit mvmts under voluntary or reflexive control?

Back 52

Voluntary

Front 53

Align the fovea of each eye with targets having different distances from the observer...???

Back 53

Vergence

Front 54

Is vergence voluntary or reflexive?

Back 54

Reflexive

Front 55

Stabilize the eyes relative to the external world thus compensating for head mvmts...???

Back 55

Vestibulo-occular mvmts

Front 56

Are vestibulo-occular mvmts voluntary or reflexive?

Back 56

Reflexive

Front 57

What are the 4 kinds of stereotyped ey mvmts?

Back 57

Saccade

Smooth pursuit

vergence

Vestibulo-occular

Front 58

Which cranial nn innervate the extraoccular mm?

Back 58

3, 4, and 6

occulomotor, trochlear, and abducens

Front 59

Why are saccades described as ballistic?

Back 59

rapid movement of eyes that abruptly change the point of fixation.

Front 60

What sensory modalities can elicit eye mvmts?

Back 60

Visual, Auditory, Somatic

Front 61

Where is the vertical gaze center?

Back 61

Rostral interstitial nucleus

Front 62

Where is the horizontal gaze center?

Back 62

paramedian pontine reticular formation

Front 63

Describe the organization of autonomic innervation to an effector....????

Back 63

Preganglionic--From CNS > Ganglion

Postganglonic---From Ganglion to effector

Front 64

What NT is used between Preganglionic and post ganglionic nn?

Back 64

Ach

Front 65

What NT is used between Post-ganglionic nn and effector?

Back 65

Ach, NE, Epi, or neuropeptide

Front 66

What are the 2 major subdivisions of the autonomic NS?

Back 66

Sympathetic and parasympathetic

Front 67

In preganglionic Ach acts on ___________Ach receptors (type)

Back 67

Nicotinic

Front 68

______ Ach receptors are ionotropic, rapid, excitatory.

Back 68

nicotinic

Front 69

Para sympathetic post-ganglionic receptors are ___________.

Back 69

Muscarinic Ach

Front 70

____________ Ach receptors use second mess. cascades, slow/prolonged responses, metabotropic.

Back 70

Muscarinic

Front 71

Which class of muscarinic receptors are excitatory?

Back 71

M(odd)

Front 72

What is the major NT used at sympathetic postgang. nn?

Back 72

NE

Front 73

What types of receptors do NE act on?

Back 73

Adrenergic

Front 74

What are the subclasses of Adrenergic receptors?

Back 74

Alpha

Beta

Front 75

The autonomic NS utilizes __________ in smooth mm as opposed to endplates found in skeletal mm.

Back 75

Varicosities

Front 76

T/F: a given area can be innervated by mx postganglionic inputs

Back 76

TRUE

Front 77

sympathetic Preganglionic originate from the _______________ and _______________

Back 77

thoracic and upper lumbar cord

Front 78

Parasympathetic preganglionics originate_____________________

Back 78

Brainstem and sacral cord--craniosacral

Front 79

Where are parasympathetic ganglia usually found?

Back 79

Near organ

Front 80

Much of parasympathetic innervation via
cranial nerves ___________

Back 80

nerves III, VII, IX, X

Front 81

Parasympathetic pre and postganglionics use what NT?

Back 81

Ach

Front 82

T/F: the autonomic NS often uses complementory/opposing actions.

Back 82

True

Front 83

are the opposing effects of sympathetic and parasymp. equal and opposite?

Back 83

NOOOOOOOOOO