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Medicine Year 1 > Nervous System > Flashcards

Nervous System Flashcards

1
Q

What is the name of cranial nerve I?

What is its function?

How would you test for it?

A

Olfactory Nerve

Smell

‘Have you noticed any changes in your sense of smell or taste recently?’

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2
Q

What is the name of cranial nerve II?

What is its function?

What is the test for it?

A

Optic

Transmission of visual information
Afferent pathway of light and accommodation reflex

Pupillary reflex, visual acuity test, visual fields test

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3
Q

What is the name of cranial nerve III?

What is its function?

How would you test for it?

A

Oculomotor

Superior rectus
Inferior rectus
Medial rectus
Inferior oblique

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4
Q

What is the name of cranial nerve IV?

What is its function?

A

Trochlear

Superior oblique

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5
Q

What is the name of cranial nerve V?

What is its function?

A

Trigeminal

Sensory and motor functions of the face:
Ophthalmic
Maxillary
Mandibular

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6
Q

What is the name of cranial nerve VI?

What is its function?

A

Abducens

Lateral rectus

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7
Q

What is the name of cranial nerve VII?

What is its function?

A

Facial

Motor function to muscles of facial expression

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8
Q

What is the name of cranial nerve VIII?

What is its function?

A

Vestibulocochlear

Auditory and vestibular info from inner ear

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9
Q

What is the name of cranial nerve IX?

What is its function?

A

Glossopharangeal

Gag reflex

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10
Q

What is the name of cranial nerve X?

What is its function?

A

Vague

Sensory - tympanic membrane, external auditory canal, external ear
Motor - muscles of palate, pharynx, larynx
Autonomic - afferents from carotid baroreceptors, parasympathetic to and from thorax and abdomen

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11
Q

What is the name of cranial nerve XI?

What is its function?

How would you test for it?

A

Accessory

Sternocladeomastoid and trapezius

Head turning and shoulder shrug

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12
Q

What is the name of cranial nerve XII?

What is its function?

How would you test for it?

A

Hypoglossal

Motor function to intrinsic muscles of the tongue

Stick out tongue and look for deviation.
Push tongue against cheek to test power.

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13
Q

What are the components of the central nervous system?

A

The brain

The spinal cord

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14
Q

What are the components of the peripheral nervous system?

A

Autonomic system

Peripheral nerves

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15
Q

What forms the grey matter?

A

Nerve cell bodies

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16
Q

Where are nerve cell bodies located?

A

on the outer layer of the cerebral cortex and brainstem

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17
Q

What forms white matter?

A

Nerve fibres

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18
Q

Where are the nerve fibres located?

A

In the inner layer of the cerebral cortex and brainstem

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19
Q

What is a nerve tract?

A

A collection of nerve fibre bundles that serve a particular function

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20
Q

Where do nerve tracts run?

A

Within the white matter

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21
Q

What is the function of the cerebral cortex?

A

conscious awareness, thought, memory and intellect

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22
Q

What lobes are contained within the posterior cerebral cortex?

A

Parietal lobe - somatosensory
Occipital lobe - vision
Temporal lobe - hearing

Thins area is involved in receiving outside information from the environment

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23
Q

What lobes are contained within the anterior cerebral cortex?

A

Frontal lobe
Organisation of movements (primary motor, pre motor and supplementary motor areas)
Strategic guidance of complex motor behaviours over time (pre-frontal area)

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24
Q

What is frontal lobe syndrome?

A

Difficulty initiating behaviour
Inability to stop a behavioural pattern
Difficulties in planning and problem solving
Incapable of creative thinking

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25
Q

What is apraxia?

A

Difficulty with planning and performing motor activities

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26
Q

What is agnosia?

A

Inability to recognise objects, faces, smells or sound

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27
Q

What is aphasia?

A

Difficulty with production and comprehension of language or speech, read or write.

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28
Q

What is amnesia?

A

Memory loss- difficulty forming new memories, recognising familiar faces or places

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29
Q

What is broca’s aphasia?

A

Also knowns a motor or non fluent (expressive) aphasia

Loss of ability to produce spoken and written language (not due to muscle impairment)

Comprehension only mildly to moderately affected

Patients know what they want to say but cant express it

(the words they use arent words)

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30
Q

What is Wernike’s aphasia?

A

Also known as receptive, sensory or posterior aphasia

Speech is fluent

Loss of language comprehension

Cant produce meaningful speech

Damage to left posterior superior temporal gyrus

(the words they use are words but dont make sense in the context)

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31
Q

What are the roles/ functions of the right side of the brain?

A 
Dressing
Drawing
Finding ones way around
Spatial imaging
Visual memory
Facial recognition
Music appreciation
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32
Q

What are the roles/ functions of the left side of the brain?

A 
Speech
Visual memory (words)
Understanding spoken language
Language related sounds
Writing
Calculation
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33
Q

What structure is the limbic lobe and where is it located?

A

A ring shaped convolution that lies on the medial side of each hemisphere and consists of part of the frontal, parietal and temporal lobes.

It surrounds the diencephalon

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34
Q

What are the main components of the limbic system?

A

Cingulate gyrus
Mamillary body
Hippocampus
Amygdala

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35
Q

What does the limbic lobe/ system do?

A

Main function is in the instinctive and emotional aspect of behaviour including motivation and memory

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36
Q

What are the basal ganglia/ nuclei?

A

A collection of nuclear masses that lie within the cerebral hemispheres

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37
Q

What are the main parts of the basal ganglia?

A

Caudate nucleus
Putamen
Globus pallidus

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38
Q

What are the main functions of the basal ganglia?

A

Control of movements and physical expression of behaviour driven by affective and motivational state

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39
Q

What is the thalamus?

A

The largest of the diencephalic derivatives and consists of numerous nuclei that form reciprocal relay connections with the cerebral cortex

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40
Q

Where is the thalamus positioned?

A

Lies between the brainstem and cerebral hemisphere

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41
Q

What is the function of the thalamus?

A

Serves as the ‘gateway’ to the cortex for most ascending pathways

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42
Q

What do thalamic lesions due to stroke or tumours lead to?

A

Loss of sensation in the contralateral face and limbs and thalamic pain

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43
Q

What is the function of the hypothalamus?

A

Has autonomic, neuroendocrine and limbic functions

Involved in the coordination of homeostatic mechanisms

Is the brain centre for regulation of autonomic nervous system:
Sympathetic -posterior
Parasyempathetic - anterior

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44
Q

What is decussation?

A

When the nerve tracts crossover to the opposite side

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45
Q

What two structures does the midbrain connect?

A

Connects the cerebral hemispheres to the pons

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46
Q

Are the functions of the cerebellum motor or sensory?

A

Motor

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47
Q

What is the function of the cerebellum?

A

Controls maintenance of equilibrium (balance), influences posture, muscle tone and coordinates movement

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48
Q

Where is the cerebellum located?

A

Carried on the back of the brainstem, connected via peduncles

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49
Q

What are the three functional subdivisions of the cerebellum?

A

Archicerebellum
Palaeocerebellum
Neocerebellum

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50
Q

What is the function of the archicerebellum?

A

Primarily concerned with the maintenance of balance (equilibrium)

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51
Q

What is the function of the paleocerebellum?

A

Influences muscle tone and posture

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52
Q

What is the function of the neocerebellum?

A

Muscular coordination including the trajectory, speed and force of movements

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53
Q

What do cerebellar lesions lead to?

A

Incoordination of the upper limbs (intention tremor), lower limbs (cerebellar ataxia), speech (dysarthria) and eyes (nystagmus).

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54
Q

What would a midline lesion cause?

A

Loss of postural control

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55
Q

What would a unilateral lesion of the cerebellar hemisphere cause?

A

Symptoms on the same side of the body - Ipsilateral incoordination of the arm (intention tremor) and of the leg, causing unsteady gait, in the absence of weakness or sensory loss.

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56
Q

What does ipsolateral mean?

A

lesion and symptom are on the same side of the body

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57
Q

What does contralateral mean?

A

lesion and symptom are on opposite sides of the body

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58
Q

What comprises Charcot’s triad and what is it used for?

A

Nystagmus (impaired eye movement coordination), dysarthria (slowness or slurring of speech) and intention tremor.

They are used for diagnosis of cerebellar disease.

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59
Q

What are the three layers of the meninges from outer to inner?

A

Dura mater
Arachnoid mater
Pia mater

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60
Q

Where is CSF produced?

A

Produced by the choroid plexus, formed by the pia mater located in the lateral third and fourth ventricles

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61
Q

What is the role of the spinal cord?

A

Carries sensory, motor and autonomic innervation for the trunk and limbs

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62
Q

Where is the spinal cord located?

A

Lies within the vertebral (spinal) canal of the vertebral column

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63
Q

Where does the spinal cord terminate?

A

At the level of the intervertebral disc between L1 and L2 in adults, L3 in newborn child

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64
Q

Why is it clinically important to know where the spinal cord terminates?

A

So as to know where to do a lumbar puncture and not hit it.

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65
Q

How many pairs of spinal nerves are there?

A

31

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66
Q

How are the spinal nerves divided eg cervical, lumbar etc…

A

8 cervical
12 thoracic
5 lumbar
5 sacral

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67
Q

After the termination of the spinal cord, what structure is formed?

A

Corda equina

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68
Q

What type of fibres do dorsal spinal roots carry?

A

Afferent fibres

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69
Q

What type of fibres do ventral spinal roots carry?

A

Efferent fibres

70
Q

What are the key ascending tracts in the spinal cord?

A

Dorsal columns tract
Spinothalamic tract
Spinocerebellar tracts (ventral and dorsal)

71
Q

What are the key descending tracts in the spinal cord?

A

Ventral corticospinal tract
Lateral vestibulospinal tract
Medial longitudinal fasciculus (medial vestibulospinal tract)
Lateral corticospinal tract

72
Q

What symptoms would a unilateral brainstem lesion cause?

A

ipsilateral cranial nerve dysfunction, contralateral spastic hemiparesis, hyper-reflexia and extensor plantar response

73
Q

What symptoms would a bilateral brainstem lesion cause?

A

Destroys the vital centres that control breathing and circulation leading to coma and death.

74
Q

What is brown-sequard syndrome?

A

Hemilesion of the thoracic spinal cord.

Results in weakness or paralysis (hemiparaplegia) on one side of the body and a loss of sensation (hemianesthesia) on the opposite side.

75
Q

What is intracranial pressure?

A

Pressure of tissues inside the cranial cavity

76
Q

What is the normal range for ICP value?

A

5-10mmHg

77
Q

What does large rises in ICP cause?

A

Impaired perfusion/ ischemia

78
Q

What does small rises or falls in ICP cause?

A

Headache/ nausea

79
Q

What is the general calculation for perfusion pressure?

A

MAP - CVP

mean arterial pressure - central venous pressure

80
Q

What happens to perfusion pressure if central venous pressure (CVP) goes up?

A

Perfusion pressure goes down

81
Q

How is cerebral perfusion pressure calculated?

A

Cerebral perfusion pressure - MAP - ICP

mean arterial pressure - intracranial pressure

82
Q

What effect does increased intracranial pressure do to cerebral perfusion pressure?

A

Increased ICP decreases cerebral perfusion pressure (CPP)

Causes vasoconstriction and may compromise vital perfusion

83
Q

What are the roles of cerebrospinal fluid?

A 
To cushion the brain
To regulate intracranial pressure
As a transfer medium for:
Nutrient delivery
elimination of metabolic products
Circulation of neurotransmitters
84
Q

Why can you get a headache after having a lumbar puncture?

A

IfCSF escapes from an LP site, a low pressure headache can result, as the brain sags, pulling on its meningeal attachments – worse on sitting/standing.

85
Q

What is the distribution of the total volume of CSF?

A

Total volume = 150mL
Cranial = 75mL
Spinal = 75mL

86
Q

What is the composition of CSF? What fluid is this similar to?

A

Similar to interstitial fluid-

No cells, virtually no protein - no buffering

87
Q

What is the most specific marker for CSF?

A

beta 2 transferrin

88
Q

In short term how is ICP regulated?

A

By adjusting volume of intracranial blood or CSF.

Veins readily change their calibre.
CSF is easily moved between cranial and spinal spaces.

89
Q

What happens to CSF if ICP is increased?

A

If ICP increases eg due to cerebral vasodilation, pressure on ventricles moves CSF to the spinal space in order to decrease ICP

90
Q

At what rate is CSF produced?

A

~500mL/day (20mL/hour)

It is energy dependant and requires N+/K+ ATPase

91
Q

Is CSF reabsorption constant or variable?

A

Reabsorption varies with ICP

92
Q

Where is CSF produced?

A

Mainly by the choroid plexus in the lateral and 3rd ventricles

93
Q

In what order does CSF circulate?

A

Circulates into 3rd ventricle via foramina of Monro

Flows into 4th ventricle via aqueduct

CSF circulates over surface of brain and spinal cord

Reabsorbed on brain surface via arachnoid granulations

94
Q

What causes hydrocephalus?

A

CSF blockage causes a rise in ICP

Can be due to a tumour or haemorrhage, commonly at the aqueduct

95
Q

How is cerebral perfusion maintained locally?

A

Constant blood flow is maintained despite varying blood pressure by changing vasomotor tone (vasodilation and vasoconstriction)

96
Q

What is the equation for maintaining perfusions pressure?

A

Q = P/R

Blood flow = perfusion pressure/ vascular tone

97
Q

What is the feedback mechanism that negates a fall in blood pressure?

A
  1. Fall in blood pressure
  2. Inadequate tissue perfusion
  3. PO2 goes down and PCO2 goes up
  4. This causes vasodilation and increases blood flow locally
  5. Cerebral blood flow is restored
98
Q

Does a fall in PCO2 cause vasoconstriction or vasodilation?

A

Vasoconstriction

99
Q

Does an increase in PCO2 cause vasoconstriction or vasodilation?

A

Vasodilation

100
Q

Does a fall in PO2 cause vasoconstriction or vasodilation?

A

Vasodilation

101
Q

How does cerebral metabolism effect cerebral bloodflow?

A

As brain activity increases, there is a greater production of metabolites (especially CO2) leading to vasodilation.
Reducing cerebral metabolism helps to keep ICP down.

102
Q

What is Cushing’s response?

A

Increased ICP will lead to an increase in cushing’s triad - increased blood pressure, irregular breathing and bradycardia

103
Q

What is the equation that explains the cushing’s response?

A

CPP = MAP - ICP

Cerebral perfusion pressure = mean arterial pressure - intracranial pressure.

104
Q

What are the two sub categories of primary intracranial injury?

A

Focal lesion

Diffuse damage

105
Q

What is the pathological progression of a secondary intracranial injury?

A
  1. Secondary injury
  2. Swelling
  3. Increased intracranial pressure
  4. Decreased Cerebral Perfusion Pressure (CPP)
  5. Decreased perfusion
  6. Ischemia
106
Q

What measures are shown to improve outcome in head injury?

A

Prevent hypertension

Avoid hypoxia

107
Q

What is coning?

A

A continuing rise in ICP forces cerebellar tonsils down into foramen magnum.
Brainstem and cranial nerves become compressed.
When ICP becomes greater than systolic BP, blood flow ceases.
The patient is said to have coned.

108
Q

What does defective ion channel coupled receptor signalling lead to?

A

Epilepsies

Cardiac dysfunction

109
Q

What does defective GPCR signalling lead to?

A

Decrease in the production of G proteins: Psuedohypoparathyroidism. Genetic loss of G(s) protein alpha subunit results in no response to parathyroid hormone

Decreased signalling initiation: Whooping cough. Bacterial toxin adds ADP ribose to the receptor-binding C-terminal tail of G(i) proteinαsubunits, causing reduced responsiveness of G proteins to receptor activation.

Increased signal initiation: Essential Hypertension. Mutations in G proteinβsubunits

Defective signal termination: Cholera or Adenomas. G proteins lose their ability to hydrolyse GTP through mutation.

110
Q

Which cranial nerves are extensions of the forebrain?

A

I and II

Olfactory and optic

111
Q

A single action potential in the presynaptic neuron (1) releases low levels of
neurotransmitter that are not high enough to trigger an action potential in the postsynaptic neuron (2). However, two or more action potential in neuron 1 in quick succession release enough neurotransmitter to trigger an action potential in neuron 2. This is an example of..?

A

Temporal summation

112
Q

What is the definition of an ionotropic receptor?

A

A membrane bound receptor that contains an ion channel

113
Q

Release of neurotransmitter from each of the presynaptic neurons (1-3) does not
trigger an action potential in the postsynaptic neuron (4). However when neurons 1-3 simultaneously release neurotransmitter an action potential is triggered. This is an example of..?

A

Spatial summation

114
Q

What are the roles of neurofibrils?

A

Provide cellular stability/ structure

115
Q

What are the role of neurotubules?

A

Microtubule transport system
Chains of tubulin running between cell body and axon terminal
Moves vesicles along the outside of the tubules using foot-like processes

116
Q

How are neurotransmitters proteins and lipids carried from the cell body to axon terminal?

A

Via kinesin along neurotubules

117
Q

How are cell debris carried from the axon terminal to the cell body?

A

Via dyenin along neurotubules

118
Q

What is myelin?

A

A white, lipid-rich wrapping layer
that surround a section of an axon
Provides electrical insulation to prevent
current loss
depolarization
takes place in the gaps (Nodes of Ranvier)
Current jumps between nodes (saltatory)

119
Q

Where are Schwann cells found?

A

Peripheral nervous system

120
Q

Where are Oligodendrocytes found?

A

Central nervous system

121
Q

What is the role of oligodendrocytes?

A

Myelination of CNS neurones

122
Q

What is the role of astrocytes?

A

Maintain microstructure (scaffolding)

Regulate blood-brain barrier

Biochemical homeostasis

Chemical communication

123
Q

What is the role of microglia?

A

Immune cells (likeness to monocytes)

Produce growth factors

124
Q

What is the role of ependymal cells?

A

Produce CSF

Line CSF spaces

Cilia aid CSF movement

125
Q

What are the three main roles of the peripheral nervous system?

A

Motor
Sensory
Automatic

126
Q

Are motor neurons afferent or efferent?

A

Efferent

127
Q

Are sensory neurons motor or sensory?

A

Afferent

128
Q

Are autonomic neurons afferent or efferent?

A

Efferent

129
Q

What two factors increase the speed of conduction?

A

Increased myelination

Larger fibre diameter

130
Q

What is the inner most layer of the meninges?

A

Pia mater

131
Q

What is the middle layer of the meninges?

A

Arachnoid mater

132
Q

What is the outer most layer of the meninges?

A

Dura mater

133
Q

How many cervical vertebrae are there?

A

8

134
Q

How many thoracic vertebrae are there?

A

12

135
Q

How many lumbar vertebrae are there?

A

5

136
Q

How many sacral vertebrae are there?

A

5

137
Q

Define sensation

A

Conscious or subconscious awareness of changes in the external or internal environment

138
Q

which type of nociceptor fibres cause fast pain?

A

myelinated A fibres (acute, sharp) - very precisely located

139
Q

Which type of nociceptors cause slow pain?

A

unmyelinated C fibres (chronic, burning) - well localised by diffuse

140
Q

What are the two main pathways for somatosensory information?

A

Lateral spinothalamic tract

Dorsal columns tract

141
Q

What will result from unilateral damage to the spinal cord (hemisection)?

A

Fine touch is lost on the ipsolateral side below cord lesion

142
Q

What will result from anterior spinal cord damage?

A

Bilateral loss of pain

143
Q

What will be affected first in an expanding central spinal cord lesion?

A

Temperature

144
Q

Is the lateral spinothalamic tract sensory or motor?

A

Sensory

145
Q

Is the dorsal columns tract sensory or motor?

A

sensory

146
Q

Is the lateral corticospinal tract sensory or motor?

A

Motor

147
Q

Is the anterior corticospinal tract sensory or motor?

A

Motor

148
Q

What area does the lateral corticospinal tract supply?

A

All spinal levels

149
Q

What area does the anterior corticospinal tract supply?

A

Neck and upper limbs

150
Q

What type of action does the lateral corticospinal tract control?

A

Most motor functions

151
Q

What type of action does the anterior corticospinal tract control?

A

Fine movements esp hands

152
Q

What is the stretch reflex?

A

Contraction of one muscle passively stretches it’s pair. A reflex arc tenses the stretched muscle in order to maintain muscle tone and stability.

153
Q

How does an upper motor neuron lesion affect muscle tone?

A

Increased spasticity

154
Q

How does an upper motor neuron lesion affect muscle bulk?

A

Unchanged (disuse atrophy)

155
Q

How does an upper motor neuron lesion affect reflexes?

A

Increased (+- clonus)

156
Q

How does an upper motor neuron lesion affect the babinski reflex?

A

Toes upgoing (babinski’s sign)

157
Q

How does an upper motor neuron lesion affect fasiculations?

A

Not present

158
Q

How does a lower motor neuron lesion affect muscle tone?

A

Decreased (flaccid)

159
Q

How does a lower motor neuron lesion affect muscle bulk?

A

Reduced (wasting)

160
Q

How does a lower motor neuron lesion affect reflexes?

A

Decreased or absent

161
Q

How does a lower motor neuron lesion affect the Babinski sign?

A

Toes are downgoing (normal)

162
Q

How does a lower motor neuron lesion affect fasiculations?

A

Present

163
Q

Would a brachial plexus injury from a stab wound be an upper or lower motor neuron lesion?

A

Lower MN

164
Q

Would a stroke from middle cerebral artery thrombosis be an upper or lower motor neuron lesion?

A

Upper MN

165
Q

Would compression of the median nerve at the wrist (carpal tunnel syndrome) be an upper or lower motor neuron lesion?

A

Lower MN

166
Q

Would C5 nerve root irritation from spondylosis of the cervical spine be an upper or lower motor neuron lesion?

A

Lower MN

167
Q

Would transaction of the spinal cord at C6 after a cycle accident causing a fractured spine be an upper or lower motor neuron lesion?

A

Upper

168
Q

What dictates pitch in the ear?

A

Frequency

higher pitch = higher frequency, lower pitch = lower frequency

169
Q

Where are different pitches detected along the basilar membrane?

A

Higher frequencies = close to the base

Lower frequencies = close to the apex

170
Q

What dictates the volume of sound detected by the ear?

A

Amount of pressure exerted by sound waves on tympanic membrane

Loudness is identified by the amplitude of deflection at a given part of the cochlea

Medicine Year 1 (3 decks)

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