Nervous System Flashcards
(170 cards)
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?’
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
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
4
Q
What is the name of cranial nerve IV?
What is its function?
A
Trochlear
Superior oblique
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
6
Q
What is the name of cranial nerve VI?
What is its function?
A
Abducens
Lateral rectus
7
Q
What is the name of cranial nerve VII?
What is its function?
A
Facial
Motor function to muscles of facial expression
8
Q
What is the name of cranial nerve VIII?
What is its function?
A
Vestibulocochlear
Auditory and vestibular info from inner ear
9
Q
What is the name of cranial nerve IX?
What is its function?
A
Glossopharangeal
Gag reflex
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
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
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.
13
Q
What are the components of the central nervous system?
A
The brain
The spinal cord
14
Q
What are the components of the peripheral nervous system?
A
Autonomic system
Peripheral nerves
15
Q
What forms the grey matter?
A
Nerve cell bodies
16
Q
Where are nerve cell bodies located?
A
on the outer layer of the cerebral cortex and brainstem
17
Q
What forms white matter?
A
Nerve fibres
18
Q
Where are the nerve fibres located?
A
In the inner layer of the cerebral cortex and brainstem
19
Q
What is a nerve tract?
A
A collection of nerve fibre bundles that serve a particular function
20
Q
Where do nerve tracts run?
A
Within the white matter
21
Q
What is the function of the cerebral cortex?
A
conscious awareness, thought, memory and intellect
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
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)
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
25
What is apraxia?
Difficulty with planning and performing motor activities
26
What is agnosia?
Inability to recognise objects, faces, smells or sound
27
What is aphasia?
Difficulty with production and comprehension of language or speech, read or write.
28
What is amnesia?
Memory loss- difficulty forming new memories, recognising familiar faces or places
29
What is broca's aphasia?
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)
30
What is Wernike's aphasia?
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)
31
What are the roles/ functions of the right side of the brain?
```
Dressing
Drawing
Finding ones way around
Spatial imaging
Visual memory
Facial recognition
Music appreciation
```
32
What are the roles/ functions of the left side of the brain?
```
Speech
Visual memory (words)
Understanding spoken language
Language related sounds
Writing
Calculation
```
33
What structure is the limbic lobe and where is it located?
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
34
What are the main components of the limbic system?
Cingulate gyrus
Mamillary body
Hippocampus
Amygdala
35
What does the limbic lobe/ system do?
Main function is in the instinctive and emotional aspect of behaviour including motivation and memory
36
What are the basal ganglia/ nuclei?
A collection of nuclear masses that lie within the cerebral hemispheres
37
What are the main parts of the basal ganglia?
Caudate nucleus
Putamen
Globus pallidus
38
What are the main functions of the basal ganglia?
Control of movements and physical expression of behaviour driven by affective and motivational state
39
What is the thalamus?
The largest of the diencephalic derivatives and consists of numerous nuclei that form reciprocal relay connections with the cerebral cortex
40
Where is the thalamus positioned?
Lies between the brainstem and cerebral hemisphere
41
What is the function of the thalamus?
Serves as the 'gateway' to the cortex for most ascending pathways
42
What do thalamic lesions due to stroke or tumours lead to?
Loss of sensation in the contralateral face and limbs and thalamic pain
43
What is the function of the hypothalamus?
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
44
What is decussation?
When the nerve tracts crossover to the opposite side
45
What two structures does the midbrain connect?
Connects the cerebral hemispheres to the pons
46
Are the functions of the cerebellum motor or sensory?
Motor
47
What is the function of the cerebellum?
Controls maintenance of equilibrium (balance), influences posture, muscle tone and coordinates movement
48
Where is the cerebellum located?
Carried on the back of the brainstem, connected via peduncles
49
What are the three functional subdivisions of the cerebellum?
Archicerebellum
Palaeocerebellum
Neocerebellum
50
What is the function of the archicerebellum?
Primarily concerned with the maintenance of balance (equilibrium)
51
What is the function of the paleocerebellum?
Influences muscle tone and posture
52
What is the function of the neocerebellum?
Muscular coordination including the trajectory, speed and force of movements
53
What do cerebellar lesions lead to?
Incoordination of the upper limbs (intention tremor), lower limbs (cerebellar ataxia), speech (dysarthria) and eyes (nystagmus).
54
What would a midline lesion cause?
Loss of postural control
55
What would a unilateral lesion of the cerebellar hemisphere cause?
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.
56
What does ipsolateral mean?
lesion and symptom are on the same side of the body
57
What does contralateral mean?
lesion and symptom are on opposite sides of the body
58
What comprises Charcot's triad and what is it used for?
Nystagmus (impaired eye movement coordination), dysarthria (slowness or slurring of speech) and intention tremor.
They are used for diagnosis of cerebellar disease.
59
What are the three layers of the meninges from outer to inner?
Dura mater
Arachnoid mater
Pia mater
60
Where is CSF produced?
Produced by the choroid plexus, formed by the pia mater located in the lateral third and fourth ventricles
61
What is the role of the spinal cord?
Carries sensory, motor and autonomic innervation for the trunk and limbs
62
Where is the spinal cord located?
Lies within the vertebral (spinal) canal of the vertebral column
63
Where does the spinal cord terminate?
At the level of the intervertebral disc between L1 and L2 in adults, L3 in newborn child
64
Why is it clinically important to know where the spinal cord terminates?
So as to know where to do a lumbar puncture and not hit it.
65
How many pairs of spinal nerves are there?
31
66
How are the spinal nerves divided eg cervical, lumbar etc...
8 cervical
12 thoracic
5 lumbar
5 sacral
67
After the termination of the spinal cord, what structure is formed?
Corda equina
68
What type of fibres do dorsal spinal roots carry?
Afferent fibres
69
What type of fibres do ventral spinal roots carry?
Efferent fibres
70
What are the key ascending tracts in the spinal cord?
Dorsal columns tract
Spinothalamic tract
Spinocerebellar tracts (ventral and dorsal)
71
What are the key descending tracts in the spinal cord?
Ventral corticospinal tract
Lateral vestibulospinal tract
Medial longitudinal fasciculus (medial vestibulospinal tract)
Lateral corticospinal tract
72
What symptoms would a unilateral brainstem lesion cause?
ipsilateral cranial nerve dysfunction, contralateral spastic hemiparesis, hyper-reflexia and extensor plantar response
73
What symptoms would a bilateral brainstem lesion cause?
Destroys the vital centres that control breathing and circulation leading to coma and death.
74
What is brown-sequard syndrome?
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
What is intracranial pressure?
Pressure of tissues inside the cranial cavity
76
What is the normal range for ICP value?
5-10mmHg
77
What does large rises in ICP cause?
Impaired perfusion/ ischemia
78
What does small rises or falls in ICP cause?
Headache/ nausea
79
What is the general calculation for perfusion pressure?
MAP - CVP
mean arterial pressure - central venous pressure
80
What happens to perfusion pressure if central venous pressure (CVP) goes up?
Perfusion pressure goes down
81
How is cerebral perfusion pressure calculated?
Cerebral perfusion pressure - MAP - ICP
mean arterial pressure - intracranial pressure
82
What effect does increased intracranial pressure do to cerebral perfusion pressure?
Increased ICP decreases cerebral perfusion pressure (CPP)
Causes vasoconstriction and may compromise vital perfusion
83
What are the roles of cerebrospinal fluid?
```
To cushion the brain
To regulate intracranial pressure
As a transfer medium for:
Nutrient delivery
elimination of metabolic products
Circulation of neurotransmitters
```
84
Why can you get a headache after having a lumbar puncture?
If CSF 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
What is the distribution of the total volume of CSF?
Total volume = 150mL
Cranial = 75mL
Spinal = 75mL
86
What is the composition of CSF? What fluid is this similar to?
Similar to interstitial fluid-
| No cells, virtually no protein - no buffering
87
What is the most specific marker for CSF?
beta 2 transferrin
88
In short term how is ICP regulated?
By adjusting volume of intracranial blood or CSF.
Veins readily change their calibre.
CSF is easily moved between cranial and spinal spaces.
89
What happens to CSF if ICP is increased?
If ICP increases eg due to cerebral vasodilation, pressure on ventricles moves CSF to the spinal space in order to decrease ICP
90
At what rate is CSF produced?
~500mL/day (20mL/hour)
| It is energy dependant and requires N+/K+ ATPase
91
Is CSF reabsorption constant or variable?
Reabsorption varies with ICP
92
Where is CSF produced?
Mainly by the choroid plexus in the lateral and 3rd ventricles
93
In what order does CSF circulate?
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
What causes hydrocephalus?
CSF blockage causes a rise in ICP
Can be due to a tumour or haemorrhage, commonly at the aqueduct
95
How is cerebral perfusion maintained locally?
Constant blood flow is maintained despite varying blood pressure by changing vasomotor tone (vasodilation and vasoconstriction)
96
What is the equation for maintaining perfusions pressure?
Q = P/R
Blood flow = perfusion pressure/ vascular tone
97
What is the feedback mechanism that negates a fall in blood pressure?
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
Does a fall in PCO2 cause vasoconstriction or vasodilation?
Vasoconstriction
99
Does an increase in PCO2 cause vasoconstriction or vasodilation?
Vasodilation
100
Does a fall in PO2 cause vasoconstriction or vasodilation?
Vasodilation
101
How does cerebral metabolism effect cerebral bloodflow?
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
What is Cushing's response?
Increased ICP will lead to an increase in cushing's triad - increased blood pressure, irregular breathing and bradycardia
103
What is the equation that explains the cushing's response?
CPP = MAP - ICP
Cerebral perfusion pressure = mean arterial pressure - intracranial pressure.
104
What are the two sub categories of primary intracranial injury?
Focal lesion
| Diffuse damage
105
What is the pathological progression of a secondary intracranial injury?
1. Secondary injury
2. Swelling
3. Increased intracranial pressure
4. Decreased Cerebral Perfusion Pressure (CPP)
5. Decreased perfusion
6. Ischemia
106
What measures are shown to improve outcome in head injury?
Prevent hypertension
| Avoid hypoxia
107
What is coning?
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
What does defective ion channel coupled receptor signalling lead to?
Epilepsies
| Cardiac dysfunction
109
What does defective GPCR signalling lead to?
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) protein α subunits, causing reduced responsiveness of G proteins to receptor activation.
Increased signal initiation: Essential Hypertension. Mutations in G protein β subunits
Defective signal termination: Cholera or Adenomas. G proteins lose their ability to hydrolyse GTP through mutation.
110
Which cranial nerves are extensions of the forebrain?
I and II
| Olfactory and optic
111
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..?
Temporal summation
112
What is the definition of an ionotropic receptor?
A membrane bound receptor that contains an ion channel
113
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..?
Spatial summation
114
What are the roles of neurofibrils?
Provide cellular stability/ structure
115
What are the role of neurotubules?
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
How are neurotransmitters proteins and lipids carried from the cell body to axon terminal?
Via kinesin along neurotubules
117
How are cell debris carried from the axon terminal to the cell body?
Via dyenin along neurotubules
118
What is myelin?
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
Where are Schwann cells found?
Peripheral nervous system
120
Where are Oligodendrocytes found?
Central nervous system
121
What is the role of oligodendrocytes?
Myelination of CNS neurones
122
What is the role of astrocytes?
Maintain microstructure (scaffolding)
Regulate blood-brain barrier
Biochemical homeostasis
Chemical communication
123
What is the role of microglia?
Immune cells (likeness to monocytes)
Produce growth factors
124
What is the role of ependymal cells?
Produce CSF
Line CSF spaces
Cilia aid CSF movement
125
What are the three main roles of the peripheral nervous system?
Motor
Sensory
Automatic
126
Are motor neurons afferent or efferent?
Efferent
127
Are sensory neurons motor or sensory?
Afferent
128
Are autonomic neurons afferent or efferent?
Efferent
129
What two factors increase the speed of conduction?
Increased myelination
| Larger fibre diameter
130
What is the inner most layer of the meninges?
Pia mater
131
What is the middle layer of the meninges?
Arachnoid mater
132
What is the outer most layer of the meninges?
Dura mater
133
How many cervical vertebrae are there?
8
134
How many thoracic vertebrae are there?
12
135
How many lumbar vertebrae are there?
5
136
How many sacral vertebrae are there?
5
137
Define sensation
Conscious or subconscious awareness of changes in the external or internal environment
138
which type of nociceptor fibres cause fast pain?
myelinated A fibres (acute, sharp) - very precisely located
139
Which type of nociceptors cause slow pain?
unmyelinated C fibres (chronic, burning) - well localised by diffuse
140
What are the two main pathways for somatosensory information?
Lateral spinothalamic tract
| Dorsal columns tract
141
What will result from unilateral damage to the spinal cord (hemisection)?
Fine touch is lost on the ipsolateral side below cord lesion
142
What will result from anterior spinal cord damage?
Bilateral loss of pain
143
What will be affected first in an expanding central spinal cord lesion?
Temperature
144
Is the lateral spinothalamic tract sensory or motor?
Sensory
145
Is the dorsal columns tract sensory or motor?
sensory
146
Is the lateral corticospinal tract sensory or motor?
Motor
147
Is the anterior corticospinal tract sensory or motor?
Motor
148
What area does the lateral corticospinal tract supply?
All spinal levels
149
What area does the anterior corticospinal tract supply?
Neck and upper limbs
150
What type of action does the lateral corticospinal tract control?
Most motor functions
151
What type of action does the anterior corticospinal tract control?
Fine movements esp hands
152
What is the stretch reflex?
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
How does an upper motor neuron lesion affect muscle tone?
Increased spasticity
154
How does an upper motor neuron lesion affect muscle bulk?
Unchanged (disuse atrophy)
155
How does an upper motor neuron lesion affect reflexes?
Increased (+- clonus)
156
How does an upper motor neuron lesion affect the babinski reflex?
Toes upgoing (babinski's sign)
157
How does an upper motor neuron lesion affect fasiculations?
Not present
158
How does a lower motor neuron lesion affect muscle tone?
Decreased (flaccid)
159
How does a lower motor neuron lesion affect muscle bulk?
Reduced (wasting)
160
How does a lower motor neuron lesion affect reflexes?
Decreased or absent
161
How does a lower motor neuron lesion affect the Babinski sign?
Toes are downgoing (normal)
162
How does a lower motor neuron lesion affect fasiculations?
Present
163
Would a brachial plexus injury from a stab wound be an upper or lower motor neuron lesion?
Lower MN
164
Would a stroke from middle cerebral artery thrombosis be an upper or lower motor neuron lesion?
Upper MN
165
Would compression of the median nerve at the wrist (carpal tunnel syndrome) be an upper or lower motor neuron lesion?
Lower MN
166
Would C5 nerve root irritation from spondylosis of the cervical spine be an upper or lower motor neuron lesion?
Lower MN
167
Would transaction of the spinal cord at C6 after a cycle accident causing a fractured spine be an upper or lower motor neuron lesion?
Upper
168
What dictates pitch in the ear?
Frequency
| higher pitch = higher frequency, lower pitch = lower frequency
169
Where are different pitches detected along the basilar membrane?
Higher frequencies = close to the base
Lower frequencies = close to the apex
170
What dictates the volume of sound detected by the ear?
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
