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NEUR1005 > Neurophysiology, Sensory and Motor Systems > Flashcards

Neurophysiology, Sensory and Motor Systems Flashcards

1
Q

What is a motor unit?

A

A single motor neuron, its axon, and the muscle fibres that it contracts. (Basic unit of motor organisation)

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2
Q

What neurons bring about muscular contractions, where are they located and how is it done?

A

Alpha motor neurons in the spinal cord (+some in the cranial nerve nuclei) modulate muscular contractions by recruitment of motor units and changes in motor neuron firing rates.

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3
Q

What is proprioception?

A

Ability to sense body parts in relation to eachother

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4
Q

Why are motor units recruited according to the ‘size principle’

A

To generate increasing amounts of tension.

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5
Q

Straightening the elbow would be done by

A

Extensor muscles (extending the joint)

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6
Q

Bending the elbow would be done by

A

Flexor muscles (flexing the joint)

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7
Q

What is muscle spindle sensitivity controlled by?

A

Gamma efferent system from gamma motoneurons

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8
Q

What are the muscle spindle afferents?

A

Type Ia and type II

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9
Q

What’s the difference between type Ia and type II fibres?

A

Type Ia has a larger diameter, (Type Ia= very large diameter, Type II = ,mediumm diamter

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10
Q

What’s the difference between Type Ia fibres and Type Ib fibres? (3)

A

Type Ia fibres are afferents for muscle spindles, type Ib fibres are afferents for golgi tendon organs. (1) Type Ib fibres have slightly smaller diameter than type Ia fibres. (2) Ia fibres are from annulospiral endings, II fibres are from flower spray endings

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11
Q

Where are the golgi tendon organs most likely to be found?

A

Musclo-tendinous junction, in series with the extrafusal fibres of the muscle

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12
Q

What do golgi tendon organs act as?

A

Tension receptors (detect changes in tension in the muscles)

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13
Q

What is reciprocal inhibition?

A

When activation of one muscle or muscle group inhibits the antagonist(s) (opposite muscle)

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14
Q

Difference between alpha motor neurons and gamma motor neurons?

A

In the muscle spindle, alpha motor neurons contact extrafusal muscle fibre end plates, gamma motor neurons contact intrafusal muscle fibre end plates.

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15
Q

Difference between alpha + gamma motor neurons and Ia + II fibres?

A

Alpha and gamma motor neurons are efferents to the muscle spindle, Ia + II fibres are afferents to the muscle spindle

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16
Q

Are the afferent fibres cell bodies inside or outside of the spinal cord?

A

Outside, in the dorsal root ganglion

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17
Q

What is the function of the inhibitory interneuron?

A

It receives information from the afferent fibre to inhibit the antagonist muscle

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18
Q

In the Tendon Organ Reflex (Myotatic reflex) which muscles are excited and which muscles are inhibited?

A

Agonist muscles are inhibited and antagonist muscles are excited

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19
Q

What are the 3 groups of descending motor pathways of the spinal cord?

A

1) Ventromedial pathways (Group A)
2) Lateral pathways (group B)
3) Corticospinal Tract (CST)

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20
Q

Lateral pathways influence which kind of muscles

A

Distal muscles, e.g. corticospinal and rubrospinal tracts control fine, fractionated movements of the limbs and fingers

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21
Q

Ventromedial pathways control

A

Posture and balance (particularly associated with neck and axial muscles)

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22
Q

Which tracts control posture of the trunk and antigravity muscles of the limbs and which pathways to they belong to?

A

Pontine and medullary reticulospinal tracts and they belong to the ventromedial pathways

23
Q

Which tracts control posture of the head and neck and which pathways do they belong to?

A

Vestibulospinal and tectospinal, ventromedial pathways

24
Q

What are the 3 main regions controlling movement?

A

Motor cortex, basal ganglia and cerebellum

25
Q

What are the 3 main motor regions of the cerebral (motor) cortex?

A

Primary motor cortex (M1), Premotor cortex (PM) and Supplementary motor area (SMA)

26
Q

What cells project from the primary motor cortex (M1) down the corticospinal tract to contact spinal motor neurons and spinal interneurons? They control groups of related motoneurons, for which muscles are they in small, dense clusters, and for which muscles are they in broader, less dense clusters?

A

Layer V pyramidal cells. They control related MN’s in small, dense clusters for distal muscles (e.g fingers) and broader, less dense clusters for proximal muscles

27
Q

Where does the premotor cortex have strong inputs from?

A

The cerebellum via the thalamus

28
Q

Where does the supplementary motor area have strong reciprocal connections with?

A

The basal ganglia

29
Q

Which area of the motor cortex is involved with planning movements based on external cues (especially visual cues)

A

Premotor cortex

30
Q

Which area of the motor cortex is involved in planning movements based on internally generated strategies?

A

Supplementary motor area

31
Q

How many parallel fibre inputs does each Purkinje cell receive?

A

250,000

32
Q

Where do mossy fibres arise from, what do they convey, and what is the sequence of connections that follows until the Purkinje cell?

A

Mossy fibres arise from the spinal cord and pontine nuclei. From the spinal cord they convey proprioceptive feedback, from the pontine nuclei they convey cerebellar cortical information and copies of motor instruction. Spinal cord and pontine nucleus -> mossy fibres -> granule cells -> parallel fibres -> purkinje cells

33
Q

How many olivary climbing fibre inputs does each Purkinje cell receive?

A

One, although each olivary cell axon branches to give 10-15 climbing fibres.

34
Q

What in the cerebellum controls balance and eye movements?

A

The flocculo-nodular lobe

35
Q

What do the vermis and the pars intermedia do?

A

Adjust ongoing movement of the whole body

36
Q

What coordinates the planning of limb movements? Where do they project in particular?

A

Cerebellar hemispheres, project to Premotor cortex in particular

37
Q

What are the five nuclei that make up the basal ganglia?

A

Striatum (Caudate, putamen), globus pallidus, subthalamic nucleus and substantia nigra.

38
Q

What kind of disorder is Parkinsons?

A

Hypokinetic basal ganglia disorder. Prevents movement initiation

39
Q

What kind of disorders are ballism and Huntingtons disease?

A

Hyperkinetic (degeneration of striatal cholinergic and GABA-ergic neurons)

40
Q

What is noise?

A

Varying distribution of air molecules in space over time

41
Q

What does the outer ear do? (3)

A

1) Gathers sound and transforms the sound pressure at the tympanic membrane
2) Amplifies sound 10-15dB for 1.5-7kHz
3) Filters it, aiding in sound localisation

42
Q

Where are the pinna, helix, concha, external auditory meatus, auditory canal and lobule located?

A

Outer ear

43
Q

What is the middle ear comprised of?

A

Ossicles, tympanic membrane (ear drum), middle ear muscles and eustachian tube.

44
Q

What is the function of the middle ear?

A

To transfer sound energy from the external environment to the cochlea

45
Q

What is the function of the ossicles?

A

Pressure amplification by lever action

46
Q

What does the oval window connect?

A

Stapes and the cochlea

47
Q

If there is middle ear damage it is called

A

Conductive deafness

48
Q

If there is inner ear damage it is called

A

Nerve deafness

49
Q

What are the 3 ossicles called?

A

Malleus, Incus and Stapes

50
Q

How do we overcome impedance mismatching?

A

The difference in area between the tympanic membrane and the oval window means that there is greater pressure on the oval window (oval window is approx. 18.6 times smaller than tympanic membrane)

51
Q

What are the 3 compartments (scalae) of the cochlea?

A

Basilar membrane (BM), oval window and round window

52
Q

What is the function of the round window?

A

Pressure relief port for the fluid set into motion by the vibrations of the footplate by the stapes.

53
Q

Functions of the cochlea? (3)

A

Splits complex sounds into simple components (1) Amplifies the signal (2) Converts/transduces mechanical vibrations into action potentials (sensory transduction)

54
Q

What are mechanoreceptors sensitive to?

A

Physical distortion eg bending and stretching

NEUR1005 (3 decks)

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