Neuro revision Flashcards
1
Q
cerebrospinal fluid circuits in which space?
A
the subarachnoid space
- the extradural space normally consists of nothing- can fill with blood in an extradural haemorrhage
- subdural space normally consists of nothing apart from bridging veins
2
Q
the superior colliculus is part of which structure?
A
midbrain
- colliculi sit on the dorsal aspect of the midbrain
3
Q
a region of white matter is identified in the cord which contains both ascending and descending axons. what is the correct term for this?
A
funiculus
- tract contains axons travelling in a single direction only (either ascending or descending)
- fasciculus is a subdivision of a tract
4
Q
the thalamus, an important structure in the sensory system, is fond in which division of the CNS?
A
Diencephalon
5
Q
one complication of subarachnoid haemorrhage is blockage of arachnoid granulations. what might the effect of this be?
A
raised intracranial pressure
6
Q
the CNS shares an embryological origin with which other tissue?
A
the skin
- CNS is derived from ectoderm- as is skin
- gut derives from endoderm and muscle from mesoderm
7
Q
pure sensory loss in a single dermatome with no associated weakness suggests damage to which structure?
A
dorsal root
- would affect multiple dermatomes with associated weakness if the spinal cord was damaged.
- ventral root affected= weakness with no sensory loss
8
Q
which region of cortex sits anterior to the central sulcus?
A
primary motor cortex
- primary sensory cortex sits posterior to the central sulcus
- premotor area sits anterior to primary motor cortex
9
Q
which subdivision of the CNS contains cell bodies and dendrites?
A
grey matter
10
Q
which cranial nerve emerges ventrally from the ponto-medullary junction?
A
abducens nerve
- trigeminal nerve emerges from the lateral aspect of the pons
- facial nerve emerges laterally from the ponto-medulary junction
11
Q
considering the motor homunculus, which region of the body is represented most laterally in the primary motor cortex?
A
the face
- lower limbs represented medially
- hands sit in an intermediate position
12
Q
a meningomyelocoele contains what?
A
spinal cord and CSF
- meningo= meninges (hence CSF)
- myelo= cord
13
Q
which type of neurone brings information into the CNS
A
afferent neurones
- efferent neurones carry impulses away from the CNS
- interneurones connect afferents and efferents
14
Q
the hippocampus is found in which lobe of the brain?
A
temporal lobe
- sits infers-medially in the temporal lobe
15
Q
a tumour at the level of the interventricular foramen might lead to dilation of which structures?
A
lateral ventricles
- lateral ventricles drain into the interventricular foramen before entering the third ventricle
16
Q
the Raphe nuclei produce which NT?
A
5-HT (serotonin)
17
Q
an important source of dopamine for the motor system can be found in which structure?
A
substantia nigra
- resides in the midbrain
18
Q
in which regions would NA be produced?
A
locus coeruleus
19
Q
which cell type can assume a macrophage- like appearance when activated?
A
microglia
- immune- type cells
20
Q
in the midbrain, which large white matter structures connect the cerebral hemispheres to the brainstem?
A
crus cerebri / cerebral peduncles
- attach the cerebellum to the brainstem
- the superior colliculi are features of the dorsal midbrain and deal with relax actions to visual stimuli
21
Q
which cell type is primarily responsible for maintenance of the BBB?
A
astrocytes
22
Q
the fall cerebra is composed of which meningeal layer?
A
meningeal dura
- in the midline (sagittal plane) the meningeal dura separates from the periosteal layer and dips down between the hemispheres to form the falx
- periosteal dura is adhered directly to the inner table of the skull
- arachnoid sits deep to the meningeal dura
23
Q
the third ventricle drains directly into which structure?
A
the cerebral aqueduct
- from the aqueduct the CSF goes to the fourth ventricle
- the central canal of the cord emanates from the 4th ventricle and contains an insignificant amount of CSF
24
Q
which part of the bringer lies at the level of the tentorium cerebelli?
A
midbrain
- the midbrain sits in the ‘tentorial notch’ and can be compressed if the uncut of the temporal lobe herniates into the posterior fossa
25
give an example of an excitatory NT
glutamate
26
So-called 'bridging veins' transverse which space?
subdural space
| - extradural space contains branches of the middle meningeal artery
27
what is a modality?
- 'unit' of sensation, relying on a distinct receptor type
28
what are the modalities of the spinothalamic system?
(important for survival)
- pain
- temperature
- crude touch
29
what are the modalities of the dorsal column system?
- vibration
- 2 point discrimination
- proprioception
- fine touch
30
what are primary sensory neurones responsible for?
- the initial encoding of sensory information
- each primary neurone receives input from a single receptor type
- have their cell body in the dorsal root ganglion, and collect information from a single dermatome alone their peripheral axon
- project into the spinal cord alone their central axon
31
what are rapid vs slow adapting receptors?
eg mechanoreceptors
- respond best to changes in strength of stimulation
- frequency of firing diminishes rapidly after the initial stimulation
- slow adapting receptors change their frequency of firing very little after the initial stimulus - how pain is persistent
32
what is a receptive field?
region of skin that a given sensory neurone supplies
33
describe the somatosensory system order
first order sensory neurones
- cell body in DRG (sensory ganglion)
- communicate with a receptor
- central axon projects ipsilateral to the cell body of a 2nd order neurone
second order sensory neurones
- cell body in spinal cord dorsal horn or medulla
- decussate onto 3rd order neurones
third order sensory neurones
- cell body in the thalamus
- project to primary sensory cortex (post central gyrus) via internal capsule
34
through what do first order neurones of the DCML system ascend through above and below T7?
```
lower body (T7 and below)
- ascend through the gracile fasciculus to the gracile nucleus in the medulla
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upper body (T6 and above)
- ascend through the cuneate fasciculus to the cuneate nucleus in the medulla
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35
what is the pathway of second order neurones of the DCML pathway?
neurones project to contralateral thalamus in the medial lemniscus
36
what is the pathway of third order neurones of the DCML pathway?
- thalamic neurones receiving information from the lower half of the body project to medial part of primary sensory cortex
- thalamic neurones receiving information from upper half of body project to lateral part of primary sensory cortex
37
what is the topographical organisation of the dorsal columns?
- axons from the lower parts of the body run most medially
| - axons from progressively superior body segments are added laterally to the dorsal columns
38
what is the pathway of first order neurones of the spinothalamic tract?
- project onto second order neurones in the ipsilateral spinal cord dorsal horn in the segment at which they enter the cord through the dorsal root (generally)
39
what is the pathway of second order neurones of the spinothalamic tract?
- cell bodies in the dorsal horn
- axons decussate in the ventral white commissure of the cord and then go on to form the spinothalamic tract
- spinothalamic tract projects to the thalamus
40
what is the pathway of third order neurones of the spinothalamic tract?
- thalamic neurones receiving information ultimately from more inferior parts of the body project to the medial part of the primary motor cortex
- thalamic neurones receiving information from more superior parts of the body project to more lateral part of the primary motor cortex
41
what is the topographical organisation of the spinothalamic tract?
- axons from the lower parts of the body run most laterally/ superficially
- axons from progressively superior body segments are added medially/ deeper onto the spinothalamic tract
- opposite to DCML as the second order neurones decussate at the level of entry of the first order neurones
42
describe the descending modulation of pain
second order neurones of the spinothalamic system
- receive pain primary afferents and inhibitory interneurones which contain the endorphin encephalin
Encephalinergic interneurones can be activated by:
-> incoming impulses from mechanoreceptors
-> descending inputs from higher centres (eg periaqueductal grey matter or nucleus raphe Magnus)
43
a patient has loss of all sensory modalities confined to the medial surface of the upper limb including the medial surface of the hand. where is the lesion most likely to be?
ipsilateral C8 spinal nerve
| - dermatomal pattern consistent with compression of a spinal nerve at C8
44
vibration and two-point discrimination are carried in which pathways running through the cord?
dorsal column
45
a patient has loss of all sensory modalities in the left T3 dermatome, loss of pain and temperature sensation from T4 downwards on the right side and loss of vibration and light touch from T4 downwards on the left side. where is the lesion?
left side of the T3 cord segment
| - Brown Sequard syndrome caused by cord hemisection
46
in the dorsal column, which population of first order fibres ascend most medially?
lumbar
| - fibres from progressively higher body regions are added laterally to the dorsal column
47
a patient has a tumour compressing the left cerebral peduncle. what is the likely effect on the sensory system?
nothing
- cerebral peduncle contains motor fibres only
- sensory fibres ascend directly to the thalamus via Mickey mouse's 'tears'
48
in the dorsal- column medial lemniscus system first order neurones ascend the cord through which white matter region?
dorsal funiculus
- lateral funiculus contains tracts such as the corticospinal and spinothalamic whereas the ventral funiculus contains the ventral corticospinal tract and a number of other small print pathways
49
a patient who was involved in a RTA describes how he felt no pain, despite the fact that his leg had been crushed. what is a feasible neurophysiological mechanism for this?
increased activity of encephalinergic neurones in the spinal cord
- activation of descending analgesic systems from the PAG and nucleus raphe Magnus
- destruction of peripheral nerves often leads to increased sensations due to ectopic APs in first order neurones
50
the cuneate fasciculus contains fibres from which body region?
C1- T6
| - gracile fasiculus contains information from the lower half of the body
51
cell bodies of primary sensory neurones can be found in which structures?
dorsal root ganglion
52
a patient has bilateral loss of temperature and pain sensation in the C6, C7 and C8 dermatomes. they have no other neurological signs. what is the most likely reason for this?
syringomyelia affecting the C6- C8 cord segments
| - symmetrical signs are typically caused either by systemic or midline lesions
53
a patient has a dorsal column lesion. what is likely to happen if they stand up and close their eyes?
lose their balance
- equilibrium relies on having at least 2 out of 3 inputs to the brain:
vision, proprioception and input from the vestibular system
loss of two of these (proprioception and vision) and the patient will lose their balance
54
at what point do second order neurones of the spinothalamic system decussate?
at the level of entry of first order neurones
| - second order neurones in DCML system decussate in the medulla
55
thalomoperformator arteries are branches of which main artery?
posterior cerebral
- middle cerebral arteries give off similar branches called lenticulostriate arteries, supplying the basal ganglia and internal capsule
56
the lateral geniuclate nucleus projects to which lobe?
occipital lobe
- LGN part of the thalamus, relaying visual information from optic tracts to the visual cortex.
- medial geniculate nucleus involves with auditory processing
57
a patient has a tumour arising from the right cavernous sinus and invading medially towards the optic chasm. which visual field defect might this result in?
right nasal hemianopia
- if the tumour erodes medially it will destroy fibres from the temporal retina of the right eye.
- the right temporal retina subserves the nasal field (of the R eye)
= unilateral R nasal hemianopia
58
destruction of the optic tract is rare. what would be the consequence of compression of the R optic tract?
L homonymous hemianopia without macular sparing
- macular sparing is a feature of vascular lesions of the occipital lobe
- R sided lesion would cases a L sided field defect
59
photoreceptor cells synapse with which retinal cell type predominately?
bipolar cells
- ganglion cells receive inputs from bipolar cells and project to the LGN
- bipolar cells can be thought of as the first order sensory neurones of the visual system
60
internuclear ophthalmoplegia can be caused b damage to which pathway?
medial longitudinal fasciculus
- MLF helps to envoke eye movements together and integrate input from the vestibular system)
- medial leminscus contains decussating secondary order sensory fibres in the DCML system
61
a patient suffers from sudden onset of complete monocular blindness. which is the most likely site of the lesion?
optic nerve
62
amaurosis fugax is a condition that is frequently caused by a blockage of which artery?
central retinal artery
| - this is transient blindness due to hypoxia in the retina
63
in which part of the retina are cones particularly common?
macula
| - the peripheral retina have predominantly rods
64
which brain region is supplied by the middle cerebral artery?
lateral surface of the frontal and parietal lobes
- inf temporal love supplied by the post cerebral artery
- medial frontal and parietal lobe supplied by ant cerebral artery
65
homonymous superior quadrantanopia is most commonly seen in lesions to which part of the visual pathway?
Meyer's loop
| - inferior optic radiations contain fibres from the contralateral superior quarter of the field
66
patient complains of a transient loss of vision in one eye that resolved after 4 hours. blockage of which vessel caused this?
ophthalmic artery
| - typical story describing amaurosis fugax, which is transient blindness caused by blockage of the ophthalmic artery
67
in addition to the cerebellum, which structure does the sup cerebellar artery also supply?
midbrain
| - midbrain supplied by the SCA on its way to the cerebellum
68
what are the features of the accommodation reflex
- convergence= medial rectus
- pupillary constriction = constrictor pupillae
- convexity of lens to increase refractive power = ciliary muscle
69
in the internal capsule, where would fibres representing the lower limbs be found?
posterior limb
- post limb contains UMNs destined for most of the body
- genu contains UMNs destined for the face
70
which structure in the midbrain is important for motor control?
red nucleus
| - circuits involved with cerebellum and motor cortex
71
how might damage to the thalamus affect movement?
decrease movement
| - cause decreased activation of the motor cortex
72
Parkinson's disease is characterised by which triplet of signs?
tremor, rigidity and bradykinesia
73
UMN lesions lead to spasticity because..
loss of descending inhibition of LMNs
- both flexors and extensors are affected equally in UMN lesions but flexors are more powerful, hence a flexed spastic posture
74
which is the best explanation for why a stroke affecting the lateral aspect the motor cortex might compromise swallowing?
denervation of cranial nerve nuclei which distribute LMNs in the vagus nerve
75
hyporeflexia is most likely to the a feature of which condition?
early stages of UMN lesion
- flaccid paralysis due to spinal shock
- late stages of UMN lesions have hyperreflexia
76
a patient has suffered a stroke affecting the internal capsule near the genu. how will his facial weakness manifest?
weakness of the contralateral lower face
- upper face has bilateral UMN innervation, hence is spared in strokes
- lower face receives a contralateral UMN innervation
- the genu contains UMNs supplying the face
77
LMN lesions can lead to what signs?
- weakness
- hypotonia
- areflexia
- wasting
- fasciculations
- fibrillation
78
UMN lesions can lead to what signs?
- weakness
- hypertonia
- hyperreflexia
- extensor plantar reflex
- clasp knife rigidity
79
6y/o boy presents dysarthria, unsteady gait and loss of co-ordination following a chickenpox infection. He is noted to have nystagmus. What is the most likely cause of this?
all features of cerebellum lesion
| - chickenpox cerebellitis
80
A patient has suffered from a stroke affecting the primary motor cortex in the right hemisphere of their brain. On a section of medulla, indicate precisely which region contains the axons of neurones damaged by the stroke.
- ventral areas of medulla- pyramids- contain the corticospinal axons ( UMNs)
- if there are distinctive pyramids= not yet decussated yet to form the lateral corticospinal tract
- therefore if can see the pyramids- R hemisphere lesion= Ipsilateral pyramid that contains the UMNs primary motor cortex
81
Damage to the basal ganglia can also affect motor function. Using a diagram, explain how loss of dopamine from the substantia nigra pars compacta (SNc) can lead to paucity of movement.
- all depends on level of cortical activity
- loss of dopamine causes decreased activity in putamen
- this decreases the inhibition of GPi
- increases activity in GPi which causes increased inhibition of thalamus
- decreased activity in cortex decreases motor movement
82
which of the following levels of spinal cold injury is least likely to require ventilatory support? T3, C4 or L2
L2
- C4 would affect the diaphragm and intercostal muscles
- T3 would affect the intercostal muscles
- L2 would not affect any resp muscles
83
a stroke patient is found to have a homonymous inferior quadrantanopia. which lobe has been damaged?
parietal
- damage to the superior optic radiation which run in the parietal lobe
- occipital = contralateral homonymous hemianopia
temporal lobe= superior quadrantanopia
84
what is a normal ICP?
10 mmHg
85
herniation of the uncus of the temporal lobe can result in which of the following?
- ischaemia in the medial part of the motor cortex
- ipsilateral third nerve palsy
- damage to the vagus nerve
- ipsilateral third nerve palsy
| uncus sits near the third nerve
86
a patient presents with visual and sensory disturbances. examination reveals R homonymous hemianopia with macular sparing and sensory deficit affecting all of the R side. which vessel is most likely to have been occluded?
L posterior cerebral artery
| - this supplies the visual cortex and thalamus
87
a patient has suffered a stroke leading to weakness of the face and upper and lower limbs but with no other clinical features. which vessel has been occluded?
a lenticulostriate artery
- pure motor stroke
- typically in fact affecting the lenticulostriate vessels in the internal capsule
88
a stroke patient is found to have a homonymous superior quadrantanopia. which lobe has been damaged?
temporal
| - inferior optic radiations will have been damaged (Meyer's loop)
89
with regard to the corticospinal tract, the posterior limb of the internal capsule classical represents which regions of the body?
trunk and lower limbs
90
an aneuysm of the posterior communicating artery can compress which cranial nerve
occulomotor
91
occlusion of the proximal portion of the superior cerebellar artery may lead to damage to which other structure
midbrain
92
following occasion of the anterior cerebral artery a patient develops raised ICP and herniates part of their cerebral cortex. which part of the cortex is particularly vulnerable
cingulate cortex
| - herniate beneath the fall, which can itself further compress the anterior cerebral artery
93
the presence of xanthochromia in the CSF suggests what
a subarachnoid haemorrhage occurred more than 12 hours ago
94
why does dementia cause increased risk of chronic subdural haemorrhage?
causes brain shrinkage
| additional strain on bridging veins in the subdural space
