EXAM II Flashcards by Erin O

Are Renshaw cells excitatory or inhibitory? Where are they located?

Inhibitory cells = lateral inhibition

Located in the anterior horns of the spinal cord, enhances the fluidity of limb movement

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Which feature describes a unique characteristic that distinguishes a motor unit from a motor neuron pool?

Motor units are composed in intrafusal fibers, whereas motor neuron pools are composed of extrafusal fibers

Motor unit is composed of a single motor neuron, whereas motor neuron pools are composed of a group of motor neurons

Motor units innervate fibers within the same muscle, while motor neuron pools innervates a different muscle

All of the features above are unique characteristics of a motor unit

Motor unit is composed of a single motor neuron, whereas motor neuron pools are composed of a group of motor neurons

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Which of the following groups of neurons within the spinal cord contain alpha motor neurons that give rise to A alpha fibers?

a. Sensory
b. Anterior motor neurons
c. Interneurons
d. Ganglia
e. None of the above

Anterior motor neurons

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T/F Large motor neurons within the motor unit are the first to fire during an action potential

False; small motor neurons are the first

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Which of the following neurons are highly excitable?

a. Anterior motor neurons
b. Sensory
c. Interneurons
d. Motor neuron pool
e. Motor unit

Interneurons

More numerous than sensory and anterior motor neurons, smaller and highly excitable, capable of spontaneous activity, responsible for most spinal cord integrative function

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What type of signals do free nerve endings detect?

a. Noxious stimuli
b. Vibration
c. Muscle tension
d. Both dynamic and static changes in muscle length
e. Pressure

Noxious stimuli; non-myelinated, smallest diameter, smallest velocity = slow

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Which muscle sensor is arranged in parallel with extrafusal fibers?

a. Free nerve endings (Groups II and IV afferents)
b. Pacinian corpuscles (Group II afferents)
c. Golgi tendon organ (Group Ib afferents)
d. Muscle spindle (Group Ia and II afferents)
e. Merkel cells

Muscle spindle; Group Ia primary fibers and II secondary afferents

In parallel with extrafusal fibers

Group Ia = recruited during stretching; synapse directly on alpha-motor neurons of same muscle, relieving tension on muscle spindle

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Which muscle sensor detects muscle tension, thereby protecting the muscle and is arranged in series with extrafusal fibers?

a. Pacinian Corpuscle (II afferents)
b. Free Nerve Endings (III, IV afferents)
c. Golgi Tendons (Ib afferents)
d. Muscle Spindle (Ia primary fibers, II secondary afferents)

Golgi Tendons; detect muscle tension = protects the muscle, arranged in series

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Which muscle sensor is the slowest due to the fact that they are non-myelinated?

a. Golgi Tendon (Ib afferents)
b. Muscle Spindle (Ia and II afferents)
c. Free Nerve Endings (IV and III afferents)
d. Pacinian Corpuscles (II afferents)

Free Nerve Endings; Type IV afferents are the slowest and are non-myelinated

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muscle Spindle = Stretch
golgi Tendon = Tension
Pacinian = Pressure
free nerve endings = pain

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What type of fibers make up the muscle fibers, which are innervated by alpha motor neurons?

a. Intrafusal fibers
b. Extrafusal fibers
c. Innerfusal fibers
d. Interfusal fibers
e. Contractile fibers

Extrafusal fibers; innervated by alpha motor neurons

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Which portion of the muscle spindle contain no contractile fibers?

a. Peripheral region
b. Central region
c. Inner region
d. Outer region
e. None of the above

Central region = functions as a sensory receptor = Ia primary fibers and group II secondary fibers

Stimulation results in stimulation of alpha-motor neurons = contraction and shortening of muscle

When muscle is stretched, spindle is stretched

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What type of motor neurons innervated muscle spindles that are required for finer movements?

a. Alpha motor neurons
b. Beta motor neurons
c. Gamma motor neurons
d. Alpha-beta motor neurons
e. Epsilon motor neurons

Gamma motor neurons; group II afferents

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Which type of intrafusal muscle fiber are innervated by group II afferents and static gamma efferents?

a. Nuclear bag fibers
b. Nuclear chain fibers
c. Nuclear rope fibers
d. Nuclear sac fibers
e. Nuclear bar fibers

Nuclear chain fibers; detect static change in muscle length, arranged in a single row

Nuclear bag fibers = detect RATE of change in muscle length; innervated by group Ia afferents and dynamic gamma efferents

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Which gamma motor neuron excites nuclear bag intrafusal fibers?

a. A-gamma
b. Gamma-dynamic
c. Gamma-static
d. None of the above

Gamma-dynamic

All gamma motor neurons innervate intrafusal fibers and adjust sensitivity of muscle spindle

A-gamma = supplies small intrafusal fibers
Gamma static = excite nuclear chain intrafusal fibers (which detect static change in muscle length)

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What are the 3 functions of the muscle spindle?

Dynamic stretch reflex - opposes sudden change to muscle length (signals via primary nerve endings)
Static reflex - causes the degree of muscle contraction to remain relatively constant (transmitted via both primary and secondary endings)
Prevents jerkiness of body movements (damping)

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Which area(s) of the cerebral cortex generate a plan for movement and generate more complex patterns of movement?

a. Premotor and Supplementary Motor
b. Primary Motor
c. Pre motor and primary motor
d. Supplementary motor and primary motor
e. Sensory motor

Pre-motor and supplementary motor

Pre-motor = develops a “motor image”

Supplementary motor = programs complex motor sequences and mental rehearsal for a movement

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Which area(s) of the cerebral cortex excites each successive pattern of muscle activity required to achieve a motor image?

a. Premotor cortex
b. Primary motor cortex
c. Supplementary motor cortex
d. Posterior motor cortex
e. Sensory cortex

Posterior motor cortex; sends signals to (2 ways) the primary motor cortex and the the basal nuclei and thalamus then the primary motor cortex

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Cells in motor cortex are organized into vertical columns, each column stimulates a group of synergistic muscles or even a single muscle, which layer receives input signals?

a. 5th layer
b. 2-4 layers
c. 6th layer
d. 1-4 layers

2-4 layers

Pyramidal cells = 5th layer
6th layer contains neurons that communicate with other regions of the cerebral cortex

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Cells in motor cortex are organized into vertical columns, each column stimulates a group of synergistic muscles or even a single muscle, which layer contains neurons that communicate with other regions of the cerebral cortex?

a. 5th layer
b. 2-4 layers
c. 6th layer
d. 1-4 layers

6th layer

Pyramidal cells = 5th layer
Input signals received = 2-4 layers

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Which neurons are made up of alpha motor neurons and make up spinal and cranial nerves?

a. Upper motor neurons
b. Lower motor neurons
c. Interneurons
d. Primary motor neurons
e. Secondary motor neurons

Lower motor neurons

UMN = entirely within CNS, originate in cerebral cortex, cerebellum and brainstem and form descending tracts

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UMNs are classified according to where they synapse in the ventral horn, which activation system innervates postural and girdle muscles?

a. Medial activating system
b. Lateral activating system
c. Anterior activating system
d. Posterior activating system
e. Nonspecific activating system

Medial activating system

Lateral activating system = distally located muscle used for fine movements

Nonspecific activating system = facilitate local reflex arcs

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UMNs are classified according to where they synapse in the ventral horn, which activation system facilitates local reflex arcs?

a. Medial activating system
b. Lateral activating system
c. Anterior activating system
d. Posterior activating system
e. Nonspecific activating system

Nonspecific activating system

Medial = innervates postural and girdle muscles
Lateral = associated with distally located muscles used for fine movements

Which of the following describes characteristics that the corticospinal tract portrays?

a. Adds speed and agility to conscious movements and high degree of motor control (finger movement)
b. Slows speed and agility to conscious movements and low degree of motor control
c. Allows precise eye movements
d. Allows precise patterning of hands and feet
e. Corticospinal pathways is not involved in motor control

Adds speed and agility to conscious movements and high degree of motor control (finger movement)

Which cerebral cortex tract contain Betz cells? a. Corticobulbar tract b. Corticospinal tract c. Rubrospinal tract d. Reticulospinal tract e. Vestibulospinal tract

Corticospinal tract; Giant pyramidal cells in the motor cortex that send collaterals back to cortex

Stimulation of red nucleus results in what types of movements of what muscles?

Stimulation of flexors | Inhibition of extensors (antigravity muscles)

What are the three components of the vestibular apparatus?

USS Utricle Saccule Semicircular canals

Which component of the vestibular apparatus system plays a role in determining orientation of head when head is UPRIGHT? a. Utricle b. Saccule c. Semicircular canals d. Cochlea e. Endolymph

Utricle = in the horizontal plane Saccule = signals head orientation when person is lying down; vertical plane

Macula, which are found in the utricle and saccule is covered by a gelatinous layer, which structure bends cilia in the direction of gravitational pull? a. Kinocilium b. Statoconia c. Semicircular canals d. Cochlea e. Utricle

Statoconia = small Ca2+ carbonate crystals

Which area of the cerebral cortex retrieves and coordinates memorized motor sequences? a. Primary motor cortex b. Premotor cortex c. Supplementary motor area d. Somatosensory area e. Sensory area

Supplementary motor area Primary = signals motor neurons to contract skeletal muscle fibers, signals via the corticospinal/pyramidal tract Premotor = plans movements based on sensory and visual cues "motor image"

T/F The cerebellum plays major roles in the timing of motor activities and in slow, ridigity progression from one muscle to the next

False; major roles in the timing of motor activities and in RAPID, SMOOTH progression from one muscle movement to the next

All of the following are functions of the cerebellum EXCEPT: a. Not essential for locomotion b. Helps sequence motor activities c. Helps to put together the motor image d. Monitors and makes corrective adjustments to motor activities while they're being executed e. Learns by its mistakes

Helps to put together the motor image

Which of the follow brain areas does the cerebellum NOT work with? a. Brainstem b. Spinal Cord c. Cerebral cortex d. Hypothalamus e. None of the above

Hypothalamus Spinal cord = to enhance the stretch reflex Brain stem = to make postural movements Cerebral cortex = to provide accessory motor functions

Define folia

Large foled sheet of the cerebellar cortex with each fold being called a folium. Lying deep beneath the folded mass are the deep cerebellar nuclei

All of the following make up an inner layer of gray matter and are the intracerebellar nuclei EXCEPT: a. Dentate b. Emboliform c. Fusiform d. Globose e. Fastigal

Fusiform = part of the temporal and occipital lobe

List the 3 layers of the cerebellar cortex

G.P.M. Granular layer = GGG = Golgi Type II, Granular, Glomeruli Purkinje layer = Purkinje cells; ONLY OUTPUT FROM CORTEX AND NOT CEREBELLUM; ALWAYS INHIBITORY Molecular layer = SBPGG Stellate cells, Basket cells, Purkinje dendrites, Golgi Type II cells, Granule cell axons

List the 4 types of cells in the cerebellar cortex

GGBS Granular (+) Golgi (-) Basket (-) = provide lateral inhibition on adjacent purkinje cells Stellate (-) = provide lateral inhibition on adjacent purkinje cells

There consists of 30 million functional units in the cerebellar cortex, which cell that's within a cerebellar cortex layer is each functional unit centered on? a. Purkinje cell b. Basket cell c. Golgi type II cell d. Granular cell e. Stellate cell

Purkinje cell and a corresponding deep nuclear cell Output is from a deep nuclear cell Afferent inputs to cerebellum are mainly from climbing and mossy fibers

What are the 3 levels of motor control function of the cerebellum?

V.S.C. 1. Vestibulocerebellum = flocculonodular lobes + vermis 2. Spinocerebellum = vermis + intermediate zone 3. Cerebrocerebellum = lateral parts of hemispheres

What is the function of the vestibulocerebellum (motor control function of cerebellum) VSC. What type of movements are associated with this system?

Control of balance and eye movements Pendular movements If cerebellum removed = movements are slow to develop, force developed is weak, movements are slow to turn off

What is the function of the spinocerebellum system in motor control functions of the cerebellum? VSC

Functions in synergy = control of rate, force, range and direction of movement Compares two sources of info and sends corrections to motor cortex via thalamus and magnocellular portion of red nucleus

What is the function of the cerebrocerebellum in motor control functions of the cerebellum? VSC

Mostly associated with premotor, primary, and association somatosensory areas of cerebral cortex Coordination of skilled movements and speech Plans as much as 10th of a second in advance of actual movements = "motor imagery"

Define ballistic movements

Entire movements that are preplanned and set into motion to go a specific distance and then to stop i.e. rapid movements such as typing

Define Dysmetria

When movements ordinarily overshoot their intended mark and the conscious portion of the brain overcompensates in the opposite direction for the succeeding compensatory movement

Define Ataxia

Uncoordinated movements

Define Past Pointing

When a person ordinarily moves the hand or some other moving part of the body considerably beyond the point of intention A manifestation of dysmetria

Define Dysdiadochokinesia

Inability to perform rapid movements

Define Dysarthria

Failure of progression in talking

Define Cerebellar Nystagmus

Tremor of the eyeballs Failure of damping by the cerebellum

Define Hyoptonia

Decreased muscle tone

What are the 3 principal functions of the basal nuclei?

1. Plan and execute motor commands in concert with cerebral cortex; help execute subconscious but learn pattern 2. Help plan multiple parallel sequential patterns 3. Control complex patterns of motor activity

The striatum contain what two paired nuclei?

Caudate nucleus - indirect Putamen - direct

Lesions to which basal nuclei results in athetosis, which is defined as spontaneous and continuous writhing movements of the hand, arm, neck, or face? a. Subthalamus b. Globus pallidus c. Putamen d. Caudate e. Substantia nigra

Globus pallidus

Lesions to which basal nuclei results in hemiballismus, which is defined as flailing movements of an entire limb? a. Subthalamus b. Globus pallidus c. Putamen d. Caudate e. Substantia nigra

Subthalamus

Lesions to which basal nuclei results in chorea, which is defined as flicking movements in the hands, face, and other body parts? a. Subthalamus b. Globus pallidus c. Putamen d. Caudate e. Substantia nigra

Multiple small lesions in the putamen

Lesions to which basal nuclei results in Parkinson's, which is defined as rigidity, akinesia (difficulty in initiating movement), tremors, postural instability, and dysphagia (inability to swallow)? a. Subthalamus b. Globus pallidus c. Putamen d. Caudate e. Substantia nigra

Substantia nigra; normally sends dopamine secreting nerve fibers to caudate and putamen, therefore, inhibitory function is altered = rigidity

Agnosia is the inability to accurately perceive objects, with what lesion is it associated with? a. Substantia nigra b. Posterior parietal cortex c. Subthalamus d. Caudate e. Putamen

Posterior parietal cortex