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Neuro > Motor control, spinal cord and reflexes > Flashcards

Motor control, spinal cord and reflexes Flashcards

1
Q

What movements is the cerebral cortex responsible for?

A

Spontaneous, adaptive voluntary movements

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2
Q

What is responsible for involuntary movements?

A

Monosynaptic reflex arc

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3
Q

Name the four types of movement?

A

Voluntary, rhythmic, reflex and postural

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4
Q

What regions of the brain control voluntary movements?

A

Frontal lobe- Pre motor, pre frontal and primary motor

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5
Q

What type of movements are voluntary movements? (give example)

A

Complex. speaking.

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6
Q

Describe the control of rhythmic movement?

A

consciously initiated by the cerebral Cortex, maintained by subcortical structures- brain stem and spinal cord.

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7
Q

Give examples of rhythmic movements?

A

walking and breathing

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8
Q

Once initiated, what maintains rhythmic movements?

A

central pattern generators, networks of neurons.

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9
Q

Give a simple description of a reflex arc.

A

sensory nerve- intervening synapse - motor nerve- response

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10
Q

What are the two main features of reflexive movements?.

A

Rapid, autonomic

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11
Q

What is the function of postural movement?

A

maintain balance, in response to changes in body position.

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12
Q

What detects changes in body position?

A

vestibulo cochlear apparatus and proprioceptors.

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13
Q

What type of signals are produced, and where do they travel from and to?

A

descending (reticulospinal) projectiond from the brain stem to the spinal cord.

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14
Q

What are CPGs?

A

network of neurons in the brain stem or grey matter that co-ordinate motor sequences, particularly rhythmic sequences.

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15
Q

How are CPGs recruited?

A

descending projections from the brain, or can behave autonomously and start movements, protections from the brain stem can alter the movements as they occur.

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16
Q

How does the cerebral cortex have direct and indirect projections.

A

Direct- through the corticospinal tract, instigating its own movements.
Indirect- descending projections to brain stem- contributing or altering signals from there down the spinal cord- acting on the reticulospinal tract.

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17
Q

What is the relationship of the cerebellum to motor control?

A

cerebellum receives masses of sensory information and then uses this to advise the motor cortex on what to do.

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18
Q

What would be the effect on motor control of damage to the cerebellum and why?

A

no paralysis or weakness, lack of coordination and clumsiness due to no directions to frontal lobe from cerebellum on what motor sequences to do.

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19
Q

What does the pathway from the frontal lobe to the cerebellum supply about motor sequences?

A

Afferent pathways that inform the cerebellum of the upcoming movement

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20
Q

What is the role of the vestibulo cochlear system and proprioceptions with the cerebellum?

A

Relay sensory information about the movement back to the cerebellum.

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21
Q

What does the cerebellum do with this information from the inner ear and proprioceptors?

A

Compares what the expected movement with the performed movement, if there are differences it will send efferents to the frontal lobe which will correct the movement.

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22
Q

What are non ballistic movements? Relationship to cerebellum

A

Movements slow enough to be corrected mid way, as the sensory inputs to the cerebellum detect an error in the movement, the cerebellum can then tell the frontal lobe to correct the movement. will only happen if the movement is slow enough to be corrected mid way through.

23
Q

What are basal ganglia?

A

Subcortical nuclei located posterior to the forebrain.

24
Q

How are basal ganglia and the motor cortex joined?

A

Loops arise from the frontal lope pass through the basal ganglia before returning via the hypothalamus.

25
Q

What supplies these basal ganglia loops? and what are the three roles of the loops?

A

Dopamine. Learning of repetitive actions, initiate voluntary movement and to select a particular action out of a range of possibilities.

26
Q

Result of damage to the basal ganglia?

A

Movement disorders- Parkinson’s.

27
Q

What does the spinal cord develop from embryologically?

A

Neural tube

28
Q

what is the sulcus limits and what does it separate?

A

Groove on both anterior and posterior aspect of the neural tube that separates the basal plate and alar plate

29
Q

What are the basal and alar plates and where are they located in the neural tube?

A

Origins or motor and sensory neurons respectively , the basal plate is located in the anterior aspect of the neural tube- therefore motor nerve roots grow on the ventral cord. The alar plate is located on the posterior aspect of the neural tube- therefore sensory nerve roots grow on the ventral cord.

30
Q

Describe the internal structure of the spinal cord.

A

Central H shaped layer of grey matter surrounded by white matter.

31
Q

What does grey and white matter contain?

A

Grey matter- spinal nerve roots. White matter- spinal nerve axons- white as surrounded by thick myelin sheaths.

32
Q

How is the grey matter divided (ventral and dorsal)?

A

Ventral- basal plate - motor function. Dorsal - alar plate- sensory function.

33
Q

What are funiculi?

A

columns of white matter- posterior, lateral and anterior

34
Q

What do the funiculi contain?

A

White matter with ascending and descending motor and sensory (respectively) pathways

35
Q

Why do proportions of grey and white matter fluctuate throughout the spinal cord?

A

Grey matter- levels vary depending how much muscle tissue that area of the spinal cord supplies- highest in cervical and lunar sections- supplies limbs.
White matter- levels vary depending on how many motor and sensory pathways are contained in the cord, decrease down the spinal cord, as at the very top there are pathways for both upper and lower body, in the lumbar section only for lower limb.

36
Q

What are the spinal laminae?

A

Zones of grey matter in the spinal cord, I-X

37
Q

What laminae make up the dorsal horn?

A

Laminae I-IV

38
Q

How are the cell bodies in the anterior horn grouped?

A

Longitudinal columns

39
Q

What is the medial lateral gradient? And the dorsal ventral pattern?

A

Motor neurones are arranged as to what muscle groups they supply, neurones that supply distal limbs will be located laterally and ventrally, whereas as neurones supplying the muscles of the back will be medial and dorsal (erector spinal)

40
Q

What is the phrenic nucleus?

A

C3,4,5 keep the diaphragm alive

41
Q

What is onufs nucleus?

A

S2,3,4 keep shit off the floor

42
Q

What is contained within a fusiform connective tissue capsule in skeletal muscle?

A

intrafusal muscle fibres, as opposed to extrafusal fibres which are most skeletal muscle fibres.

43
Q

What is the role of intrafusal muscle fibres?

A

Sensory fibres which detect length and rate of stretch of muscle fibres. Cause reflex contraction of the same muscle group stretched.

44
Q

What is reciprocal inhibition

A

Inhibition of antagonist muscle groups in response to the stretch reflex of a muscle.

45
Q

Where in the spinal cord are lower motor neurones located?

A

Anterior horn of grey matter

46
Q

Where are upper motor neurones located?

A

Motor cortex of the frontal lobe

47
Q

Why is the stretch reflex dampened and how?

A

To ensure muscle tone is not excessive, dampened by descending pathways from the brain stem.

48
Q

Effect of an upper motor neurone lesion?

A

loss of dampening effect, leads to hypertonia. This causes extra joint resistance

49
Q

Effect of a lower motor neurone lesion?

A

Interrupts peripheral nerve pathways to the muscle groups, meaning no motor innervation. Causes paralysis and atonia. causes atrophy over time

50
Q

Causes of upper and lower motor neurone disease?

A

UMN- stroke. LMN- anterior horn cell disease (polio).

51
Q

What is the withdrawal reflex?

A

automatic limb withdrawal form a noxious stimulant.

52
Q

What governs the withdrawal reflex?

A

Flexor reflex and the crossed extensor reflex.

53
Q

Outline how the flexor and crossed extensor reflex work

A

Flexor- polysynaptic reflex triggered by nociceptors in the skin, causes flexion of limb withdrawing it from the stimulus.
Crossed extensor- coupled with flexor reflex, extends the opposite limb in opposite direction to maintain balance and stop falling.

Neuro (11 decks)

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