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NEUROLOGY > NEUROLOGICAL PRINCIPLES > Flashcards

NEUROLOGICAL PRINCIPLES Flashcards

1
Q

Signs of UMN lesions

A

Weakness - extensors weaker than flexors in the arms, flexors weaker than extensors in legs
Hyper-reflexia + positive Babinski sign
Spasticity
Slight or absent muscle wasting
No fasciculations

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2
Q

Signs of LMN lesions?

A

Marked atrophy
Fasciculations
Reduced tone
Weakness/decreased power
Hyporeflexia + Absent plantar response

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3
Q

Ascending spinal tracts?

A

Dorsal column medial lemniscal
Posterior spinocerebellar
Anterior spinocerebellar
Spinal-olivary
Anterior and lateral spinothalamic

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4
Q

Descending spinal tracts?

A

Anterior and lateral corticospinal
Medial and lateral reticulospinal
Rubrospinal
Vestibulospinal
Tectospinal

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5
Q

Function of dorsal column pathway?

A

Fine touch, proprioception and vibration

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6
Q

Function of anterior spinothalamic tract?

A

Crude touch and pressure

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7
Q

Function of lateral spinothalamic tract?

A

Pain and temperature

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8
Q

Types of spinocerebellar tracts?

A

Dorsal spinocerebellar tract.
Ventral spinocerebellar tract.
Posterior external arcuate fibers.
Rostral spinocerebellar tract.

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9
Q

Posterior spinocerebellar tract function?

A

Proprioceptive information from lower limb and trunk

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10
Q

Anterior spinocerebellar tract function?

A

Proprioception from the lower limbs

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11
Q

Cuneocerebellar tract function?

A

Proprioceptive infromation from the upper limbs

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12
Q

Which ascending pathways are conscious?

A

Dorsal column
Spinothalamic

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13
Q

Which ascending pathways are unconscious?

A

Spinocerebellar
Spinotectal
Spinoreticular
Spinal-olivary

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14
Q

Function of spinotectal pathway?

A

enables us to orient our eyes and move our head toward the relevant stimulus

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15
Q

Function of spino-olivary pathway?

A

Proprioceptive information from muscles and tendons

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16
Q

Function of spinoreticular tract?

A

To increase our level of arousal in response to pain or temperature

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17
Q

Neuronal pathway of dorsal column medial lemniscal tract?

A

First order neuron - peripheral axons recieve signal inputs from skin and enter the Fasciculis gracilis (if <T6) or fasciculis cuneatus (if T6 or above). They synapse in the nucleus gracilis or nucleus cuneatus in the medulla respectively

Second order neuron - axons from nucleus gracilis and nucleus cuneatus decussate within the medulla and then travel up the contralateral medial lemniscus to the thalamus

Third order neuron - axons from the thalamus go through the internal capsule and terminate in the primary somatosensory cortex of the post central gyrus

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18
Q

Neuronal pathway of the spinothalamic tract?

A

First order neurones - arise from the sensory receptors in the periphery, enter the spinal cord via dorsal grey horn. They ascend 1-2 vertebral levels and then synapse at the substantia gelatinosa in the tip of the dorsal horn

Second order neurones - these fibres decussate and now form 2 distinct tracts the anterior and lateral spinothalamic tract. These run alongside each other and travel superiorly within the spinal cord, synapsing in the thalamus

Third order neurones - they ascend from the ventral posterolateral nucleus of the thalamus, travel through the internal capsule and terminate at the sensory cortex

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19
Q

What are the 2 main groups of descending (motor) spinal tracts?

A

Pyramidal and extrapyramidal

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20
Q

What are pyramidal spinal tracts?

A

Tracts that originate in the cerebral cortex carrying motor fibres to the spinal cord and brainstem
Responsible for voluntary control of the musculature of the body and face
They travel through the pyramids

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21
Q

What are extrapyramidal tracts?

A

Spinal tracts that originate in the brainstem, carrying motor fibres to the spinal cord
Responsible for the involuntary and automatic control of all musculature e.g. tone and balance
Dont travel through pyramids

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22
Q

How many neurones are typically involved in descending spinal tracts?

A

2 - UMN and LMN

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23
Q

What are the 2 pyramidal spinal tracts?

A

Corticospinal tracts and corticobulbar tracts

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24
Q

Function of corticospinal tracts?

A

Voluntary motor control of the body and limbs

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25
Q

Structure of the corticospinal tracts?

A

Cerebral cortex receives input from primary motor cortex, premotor cortex, supplementary motor area and some input from somatosensory area
Neurones converge and descend through the internal capsule
They then pass through thr midbrain, pons and enter the medulla
In the caudal part of the medulla the tract divides into the lateral and anterior corticospinal tract

80% - Fibres within the lateral corticospinal tract decussate an then descend into the spinal cord, terminating in the ventral horn at all segmental levels. From the ventral horn, LMN go on to supply the muscles of the body

20% - Fibres within the anterior corticospinal tract remain ipsilateral, descending into the spinal cord. They decussate and terminate in the ventral horn of the cervical and upper thoracic segmental levels

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26
Q

Anterior vs lateral corticospinal tract functions?

A

Anterior - movement of muscles of trunk, neck and shoulders
Lateral - movement of muscles in limbs

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27
Q

Corticobulbar tracts function?

A

Innervates muscles of the face, head and neck

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28
Q

Structure of corticobulbar tract?

A

Primary motor cortex receives a range of inputs and these fibres converge and pass through the internal capsule to the brainstem
Neurones terminate on the motor nuclei of CN where they synapse with LMN which carry the motor signals to the muscles of the face and neck

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29
Q

Does the corticobulbar tract supply unilateral or bilateral innervation to motor neurones?

A

Bilateral

Except for:
CN VII
CN XII
Both only provide contralateral innervation

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30
Q

Which extrapyramidal tracts decussate and therefore provide contralateral innervation?

A

Rubrospinal and tectospinal

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31
Q

Function of vestibulospinal tracts?

A

Vestibular nuclei receptive input from organs of balance and tracts convey this information to the spinal cord, where it remains ipsilateral
Fibres control balance and posture by innervating anti-gravity muscles via LMN

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32
Q

What are anti-gravity muscles?

A

Flexors of arms
Extensors of legs

33
Q

2 reticulospinal tracts?

A

Medial and lateral

34
Q

Where does the medial reticulospinal tract rise from and what is its function?

A

Arises from the pins
Facilitates voluntary movements and increases muscle tone

35
Q

Where does the lateral reticulospinal tract rise from and what is its function?

A

Arises from the medulla
Inhibits voluntary movements and reduces muscle tone

36
Q

Where does the Rubrospinal tract rise from and what is its function?

A

Originates from the red nucleus in the midbrain
Thought to play a role in the fine control of hand movements
(Remember with rubrix cube)

37
Q

Where does the tectospinal tract rise from and what is its function?

A

Arises in superior colliculus of the midbrain which receives input from optic nerves
Coordinates movements of the head in relation to vision stimuli

38
Q

Does the dorsal spinocerebellar tract decussate?

A

No

39
Q

Does the anterior spinocerebellar tract decussate?

A

Yes twice so it remains ipsilateral

40
Q

Signs of UMN lesion?

A

Flexion of UL and extension of LL
Hypertonia - clasp knife spasticity
Pyramidal weakness
Brisk reflexes
Scissor or hemiplegic gait

41
Q

What is pyramidal weakness?
What causes it?

A

Weakness that preferentially spares the antigravity muscles e.g. weakness of upper limb extensors and lower limb flexors
Caused by UMN lesions

42
Q

What is clasp knife spasticity?

A

This is an initial resistance when attempting passive movement of the extremities, followed by a rapid decrease in resistance
Commonly due to UMN lesions

43
Q

What is scissoring gait?

A

Aka diplegic gait
Knees and thighs pressed together or crossing each other whilst walking. In an attempt to overcome this adduction, the pt circumducts both legs during the swing phase
Cased by spasticity in the hip adductors
Associated with UMN lesions
Bilateral!

44
Q

What is hemiplegic gait?

A

gait in which the leg is held stiffly and abducted with each step and swung around to the ground in front, forming a semicircle
Caused by UMN lesions
Unilateral!

45
Q

If a patient has all four limbs affected, where in the spinal cord is the lesion likely?

A

Cervical region

46
Q

If a patient has only the lower limbs affected, where in the spinal cord is the lesion likely?

A

In the thoracic region

47
Q

If a patient has respiratory diffiuclties, where in the spinal cord is a lesion likely?

A

Above C3

48
Q

Causes of spinal cord lesions?

A

MS
Neuromyelitis optica
Infections
Subacute combined degeneration of the cord
Spinal ischaemia e.g. stroke
Intrinsic neoplasm
Hereditary spastic paraparesis
Fracture
Prolapse disc
Haematoma
Osteomyelitis or discitis
Abscess
Metastatic disease
Myeloma

49
Q

Which cranial nerves are not considered peripheral nerves?

A

CN I and CN II
These are considered extensions of CNS

50
Q

What gait is commonly seen in LMN lesions?

A

High stepping or foot-drop gait

51
Q

Symptoms and signs of cerebellar disorders

A

DANISH:
Dysdiadochokinesia, dysmetria, ‘drunk’ appearance
Ataxia
Nystagmus
Intention tremor
Slurred speech
Hypotonia and hyporeflexia

52
Q

Causes of cerebellar syndrome?

A

Friedreich’s ataxia, ataxic telangiectasia
neoplastic: cerebellar haemangioma
stroke
alcohol
multiple sclerosis
hypothyroidism
drugs: phenytoin, lead poisoning
paraneoplastic e.g. secondary to lung cancer

53
Q

Functions of the frontal lobe?

A

Intellectual function e.g. planning, problem solving, decision making, judgement
Praxis (the ability to perform skilled or learned movements)
Inhibition
Bladder continence
Saccadic eye movements (quick simultaneous movements of both eyes that shifts the centre of gaze from 1 part of the visual field to another)
Motor function
Expression of language (Brocas area)

54
Q

Functions of the temporal lobe?

A

Encoding of memories
Processing auditory, visual, olfactory and language sensory input

55
Q

Functions of the parietal lobe?

A

The major sensory processing hub for the brain
Recieve and process sensory input e.g. touch, pressure, heat, pain, smell, sight

56
Q

Functions of the occipital lobe?

A

Major visual processing region

57
Q

Functions of the cerebellum?

A

Coordinates gait
Maintains posture
Controls muscle tone ans voluntary muscle activity

Basically it receives information from the sensory systems and regulates control of movements

58
Q

Where are primary motor neurones situated?

A

In the primary motor cortex which is in the pre central gyrus
This is Brodmann area 4

59
Q

Describe how the neurones are situated topographically in the motor cortex?

A

They form the motor homonculus

Face and mouth are near the Sylvian fissure
Arm and hand are at the mid portion of the primary motor cortex
The trunk is near the apex of the brain
Leg and foot areas are in the part of the primary cortex that dips into the longitudinal fissure

60
Q

Describe where in the brainstem the cranial nerves are?

A

Midbrain - III and IV
Pons - V, VI, VII, VIII
Medulla - IX, X, XI and XII

61
Q

Function of the substantia nigra in the brainstem?

A

Dopamine production

62
Q

Function of the red nucleus in the brainstem?

A

Involved in limb control and motor coordination
E.g. in a vertebrate without a significant corticospinal tract, gait is mainly controlled by the red nucleus - less useful in primates
E.g. crawling of babies is controlled by this

63
Q

What is Weber syndrome?

A

Midbrain stroke syndrome
A form of stroke that affects the medial portion of the midbrain - mainly caused by occlusion of a branch of the posterior cerebral artery

64
Q

What is wallenberg’s syndrome?

A

Lateral medullary syndrome
Stroke in the lateral portion of medulla.
Caused by occlusion of posterior inferior cerebellar artery

65
Q

Brainstem functions?

A

Site of origin of CN nuclei 3 to 12
Dopamine production
Coordination of movement
Respiratory centre
Cardiac centre
Reticular activating system
Conduit for white matter tracts - motor, sensory, coordination, eye movements

66
Q

What are the 3 anatomical lobes of the cerebellum?

A

Anterior lobe
Posterior lobe
Flocculonodular lobe

67
Q

What are the 3 functional divisions of the cerebellum?

A

Cerebrocerebellum
Spinocerebellum
Vestibulocerebellum

68
Q

Function of the cerebrocerebellum?

A

Involved in planning movements and motor learning - receives inputs from cerebral cortex and pontine nuclei and sends outputs to thalamus and red nucleus
Regulates coordination of muscle activation and is important in visually guided movements

69
Q

Function of the spinocerebellum?

A

Regulates body movements by allowing for error correction
Maintenance of tone

70
Q

Function of the vestibulocerebellum?

A

Controls balance and ocular reflexes
Receives inputs from the vestibular system and sends outputs back to the vestibular nuclei

71
Q

If a limb weakness is fatigable where is the likely pathology occuring?

A

Neuromuscular junction

72
Q

What is autonomic dysreflexia?

A

A clinical syndrome that occurs in pt who have a spinal cord injury at or above T6
Afferent signals most commonly triggered by faecal impaction or urinary retention cause a sympathetic spinal reflex via thoracolumbar outflow. This results in an unbalances physiological response characterised by extreme hypertension, flushing & sweating above the level of the spinal cord lesion, agitation, bradycardia
In untreated cases severe consequences of extreme hypertension can occur e.g. haemorrhagic stroke

73
Q

What is Hoffman test?

A

When doctor flicks the fingernail of the middle finger down and the thumb will flex = indicates UMN lesion and is likely cervical

74
Q

What does past pointing in finger-nose coordination test tell you?

A

Pt has dysmetria - sign of cerebellar damage

75
Q

What spinal level is the biceps brachii reflex?

A

C5 and C6

76
Q

What spinal level is the triceps brachii reflex?

A

C6, C7, C8

77
Q

What spinal level is the brachioradialis reflex?

A

C5, C6, C7

78
Q

What spinal level is the quadriceps femoris reflex?

A

L2, L3, L4

79
Q

What spinal level is the Achilles tendon reflex?

A

S1, S2

NEUROLOGY (16 decks)

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