30/09/20 Flashcards
(151 cards)
1
Q
Which are more abundant? Neurons or glial cells?
A
Glial cells are 5x more abundant than neurons
2
Q
What are the glial cell types in the CNS and what do they do?
A
Oligodendrocytes myelinate axons in CNS and provide overall structural framework to it.
Astrocytes are important for blood-brain barrier.
Microglia remove waste, pathogens, debris by phagocytosis.
Ependymal cells line ventricles of brain and central canal of spinal cord – produce CSF.
3
Q
What are the glial cells in the PNS and what do they do?
A
Satellite cells maintain nutrient and neurotransmitter levels around cells.
Schwann cells myelinate axons in PNS.
4
Q
When does the cranial neuropore close?
A
Day 25
5
Q
When does the caudal neuropore close?
A
Day 27
6
Q
What are the three primary brain vesicles and when do they form?
A
Week 4
Prosencephalon
Mesencephalon
Rhombencephalon
(Pro Me at Rhombus)
7
Q
What are the secondary brain vesicles and when do they form?
A
Week 6
Telencephalon
Diencephalon
Mesencephalon
Metencephalon
Myelencephalon
(Telephone Diana, Me Met Myelen)
8
Q
What structures do the secondary brain vesicles form?
A
Telencephalon –> Cerebral hemispheres
Diencephalon –> Thalamus/Hypothalamus
Mesencephalon –> Midbrain
Metencephalon –> Cerebellum and pons
Myelencephalon –> Medulla
9
Q
What is the calcarine sulcus?
A
In occipital lobe, associated with primary visual cortex.
10
Q
What does the cingulate gyrus do?
A
Cingulate gyrus controls heart rate, resp rate, pain processing and bladder control.
11
Q
What is the brodmann areas of the somatosensory cortex?
A
1
12
Q
What is the Brodmann area of the primary motor cortex?
A
4
13
Q
What is the Brodmann area of the pre-motor cortex?
A
6
14
Q
What is synaesthesia?
A
Synaesthesia refers to a combination of senses that provides an unusual interpretation
15
Q
What do association fibres connect?
A
Association fibres (within a hemisphere)
16
Q
What do commissural fibres connect?
A
Commisural fibres (between hemispheres)
17
Q
What do projection fibres connect?
A
Projection fibres (to brainstem/spinal cord)
18
Q
What does the tentorium cerebelli do?
A
Prevents occipital lobe compressing the cerebellum especially during neck/head flexion & extension
19
Q
What is a Jefferson fracture?
A
C1 (Atlas) shattered
20
Q
Where is a Dens fracture and how can this occur?
A
C2 (Axis) Dens fracture (#) can occur via rapid flexion-extension of the neck e.g. rapid deceleration in a motor vehicle collision
21
Q
What is a hangman fracture?
A
Neural arch is broken off from the body of the vertebrae (C2?).
Weight of cranium moves C1 and C2 anteriorly, causing kink in spinal cord.
22
Q
What is vertebrae promininens and where is it found?
A
Vertebrae prominens
The first prominent spinous process
C7
23
Q
What are the differences between the vertebral bodies as you go down the vertebral column?
A
Cervical vertebrae have bifid process and foramen transversarium
Thoracic vertebrae have heart-shaped body
Lumbar vertebrae have kidney-shaped body and short and square spinous process body
24
Q
What could you use the C7 transverse process (vertebrae prominens) for?
A
Lung apex
25
What are the zygapophyseal joints?
Located between articular facets of adjacent vertebrae
Simple synovial plane joints
Facets change orientation from superior-to-inferior
Joints can dislocate leading to vertebral body displacement – can compress vertebral canal
26
What is spondylolysis?
Fracture in the region of the articular facets without displacement
Scotty dog with collar
27
What is spondylolisthesis?
Lumbar vertebrae body slips or moves anteriorly. Can be due to a traumatic, degenerative or dysplastic cause. Often accompanies spondylolysis.
28
In hyperkinetic disorders, is there reduced or increased activity of GPi?
Reduced
29
In hypokinetic disorders, is there reduced or increased activity of GPi?
Increased
30
What will you get with a cerebellar hemisphere lesion?
Ipsilateral problems with limbs (Appendicular ataxia),
| dysdiadochokinesia, dysmetria
31
What will you get with a vermil lesion?
Truncal ataxia
32
What will you get with a floculo-nodular lesion?
Dizziness
33
What do Meissner corpuscles detect?
Discriminative touch
34
What do pacinian corpuscles detect?
Deep pressure and vibration
35
What do Ruffini endings detect?
Touch
36
What do Merkel discs detect?
Light touch
37
What do free nerve endings detect?
Pain and temperature
38
In the dorsal column pathway from the face, what tract do the second order neurons travel in?
Trigeminal lemniscus to VPM of thalamus
39
What can happen with dorsal column damage at the spinal cord? What can cause this?
Can be caused by tertiary syphilis (demyelination of dorsal column), compression, infarction, infection or B12 deficiency.
Symptoms will be ipsilateral following spinal cord damage.
Pseudoathetosis
Sensory ataxia leading to positive Romberg sign and stamping gait
40
What will syringomyelia affect?
Affect DECUSSATING neurons in the STT
| You get that cape like sensory loss
41
What is the significance of Clarke's Dorsal Nucleus?
Lower limb muscle spindle info enters cord and synapses in Clarke’s Dorsal Nucleus, then ascends in the DSCT
(Sits between ~C8-L3)
Clarke’s Nucleus is one of the areas affected in Freidrich’s ataxia
42
What would damage to the spinocerebellar tract look like?
Symptoms normally masked by other motor weakness/paralysis
Pure lesions could cause:
- Ataxia / malcoordination of motor action
- Wide-based gait
43
What is a motor unit?
Motor unit = a lower motor neuron & the extrafusal muscle fibres it innervates
Powerful muscles have lots of muscle fibres per motor unit. Fine control has fewer muscle fibres per motor unit.
44
In the motor homunculus, what is found inside the longitudinal fissure?
legs
45
What do alpha motor neurons innervate?
a motor neurons innervate MOTOR UNITS of Extrafusal fibres
46
What do gamma motor neurons innervate?
g motor neurons innervate Intrafusal fibres of MUSCLE SPINDLES
47
What degeneration is seen in ALS?
Degeneration of the corticospinal tracts and ventral horn of the spinal cord
UMN and LMN symptoms are seen together
Often limb onset first --> then spreading to other areas of body
Fasciculations
Spasticity/Cramps
Weakness (limbs, neck, diaphragm)
Dysarthria, dysphagia, dyspnoea
48
Where do ventral CST UMNs decussate?
Only at the level where it exits the spinal cord.
49
What symptoms would you get with a CST lesion?
Corticospinal tract lesions (primarily LATERAL Tract - since it carries most the fibres)
can be associated with loss of fine-skilled voluntary movements and other signs
1) Abdominal reflexes
2) Cremasteric reflex
3) Ankle clonus
4) Babinski sign
Clonus = rhythmic series of contractions (oscillations) caused by the alternate stretching & unloading of muscle spindles in a patient with spastic muscles
50
What does the lateral vestibulospinal tract do?
Increases EXTENSOR muscle tone (anti-gravity muscles, keep you upright!)
51
Where do reticulospinal tracts originate from?
Originate from nuclei in the pons/medulla
52
Why can patients smile, even if they have bilateral corticobulbar lesions to CN VII?
Reticulospinal tract is still in tact and controls emotional movement of muscles of facial expression
53
What are the 2 parts of the Reticulospinal tract?
the Medullary and Pontine Tracts
| The Medullary Tract and Nucleus helps to control the Sympathetic Chain
54
Describe the stages in the myotatic reflex
1) A passive muscle stretch is sensed by muscle spindle
2) Reflex arc stimulates a contraction of the stretched muscle
3) Reflex arc inhibits antagonist muscle from contracting (relaxes the opposing muscle)
55
Describe the flexor reflex
Quick withdrawal of a limb from a painful (noxious) stimuli
```
Mediated by free nerve endings
Synaptic connections span several spinal cord levels
Stimulates ipsilateral flexors of limb
Inhibits ipsilateral extensors of limb
```
56
Describe the crossed extensor reflex
Activation of the flexor reflex in a weight-bearing limb
Ipsilateral flexor withdrawal
Contralateral extensor activation
57
On T2 MRI, what appears black and what appears white?
- Bone appears as black
| - CSF appears white
58
What parts of the brain does the pupillary light reflex test?
Tests functioning of the retina, CN II, Midbrain and CN III
59
How does glaucoma affect the visual fields?
Reduces the visual fields
60
How does retinitis pigmentosa affect the visual fields?
Causes tunnel vision
61
What does papilloedema look like?
Raised disc, engorged veins
62
What does oculomotor nerve innervate?
4/6 extraocular eyeball muscles, levator palpebrae superioris (eyelid muscle), sphincter pupillae (lens accommodation), and ciliary muscle of the eye (to constrict pupil)
63
What would happen with a CN III lesion?
```
Complete Ptosis on affected side
Eye is ‘Down & Out’: Exotropia
unopposed LR (CN VI) / SO (CN IV)
Dilated, Non-Reactive Pupil
Consensual light reflex intact in unaffected eye
Diplopia: Double vision (horizontal & vertical)
```
64
What is special about CN IV?
CN IV is the ONLY cranial nerve to emerge from the dorsal side of the brainstem, and the ONLY cranial nerve to decussate before it even emerges from the brainstem!
65
What would happen with a CN IV lesion?
Upward deviation and extorsion (outward rotation of the eye)
Vertical diplopia: worse when looking down (e.g. going down stairs/reading)
66
What would happen with a CN VI lesion?
If lesioned, you will not have lateral movement of the eye
Eye rests in adducted position = convergent squint
Horizontal diplopia
Diplopia worse when looking toward
67
What will damage to CN III, CN IV and CN VI lead to?
Lesions can also lead to:
Diplopia
Compensatory head movements
Horizontal diplopia can indicate medial (CN III) or lateral rectus (CN VI) issues
Vertical diplopia can indicate issues with Superior oblique (CN IV) / Inferior oblique or rectus (CN III)
68
Where do CN V fibres exit the brainstem?
Lateral pons
69
What innervates the angle of the mandible?
cervical nerves, NOT CN Vc
70
What side will the mandible deviate towards in a CN V motor lesion?
Jaw jerk exaggerated in UMN lesions
Open mandible - deviates toward weak side due to opening action of medial pterygoid muscle
71
What nuclei does the facial nerve come from?
Facial nucleus & Superior Salivatory nucleus (Pons)
72
What foramen does CN VII pass through?
Internal Acoustic Meatus and Stylomastoid foramen
73
What does the Greater Petrosal Nerve supply?
Parasympathetic to lacrimal gland and salivary glands
74
What do you get with an UMN lesion (eg. stroke) of CN VII?
Forehead sparing
75
What do you get with a LMN lesion (eg. Bell's palsy) of CN VII?
Full ipsilateral palsy
76
How do you test the vestibular portion of CN VIII?
Tested if patient complains of episodes of vertigo
Hallpike Manoeuvre
Positive test produces vertigo rotatory nystagmus toward affected side
77
What nuclei does CN IX originate from?
Inferior salivatory; nucleus ambiguus; nucleus solitarius (Medulla)
78
What nuclei does CN X originate from?
Dorsal motor; nucleus ambiguus; nucleus solitarius (Medulla)
79
What muscles does CN XI innervate?
Sternocleidomastoid and trapezius
80
What can lesion of CN XI lead to?
SCM weakness can sometimes lead to head turned to weak side at rest
81
Which side does the tongue deviate to in a CN XII lesion?
Deviates towards weak side
82
What is the reticular formation?
Reticular formation is a network of neurons responsible for core physiological processes and states of consciousness.
83
Where does CN V exit the brainstem?
Pons
84
Where do CN VI, VII and VIII exit the brainstem?
Pontomedullary junction
85
Where do CN III and IV exit the brainstem?
Midbrain
86
Where do CN IX and X exit the brainstem?
Lateral medulla
87
Where does CN XI originate from?
C1-C5 spinal cord
88
Where does CN XII exit the brainstem?
Ventral medulla
89
Which cranial nerve emerges from the interpeduncular fossa?
CN III
90
What does CN VII wrap around and what can it be compressed by?
CN VII wraps around CN VI and can be compressed by 4th ventricle tumours
91
Which cranial nerves hitchhike on CN V's sensory nucleus? And which part of the nucleus?
CN VII, IX and X hitchhike on the spinal nuclei
92
What is bulbar palsy?
Lower motor neurone lesion affecting CN VII - XII
Paralysis of pharynx, soft palate, larynx, tongue (sometimes the face & mastication)
Dysarthria, dysphonia, drooling, poor swallowing, aspiration
Flaccid paralysis, wasting, fasciculations
Causes = Polio, radiotherapy, CVE
93
What is pseudo-bulbar palsy?
Bilateral corticobulbar tract disorder (upper motor neurone lesion)
Presents initially as LMN lesion; LMN and reflex arc remain functional
Bilateral damage is clinically significant
Similar symptoms to bulbar palsy but can develop spastic paralysis of pharynx & larynx = airway occlusion emergency
Causes = Head injury, CVE, high brainstem tumour…..
94
Which cranial nerves could a Superior cerebellar artery aneurysm compress?
CN III and CN IV
95
Which cranial nerves could a PCA aneurysm compress?
CN III and CN IV
96
What would happen with CN IV motor nucleus damage?
CN IV nucleus damage leads to contralateral loss of superior oblique function
Diplopia when reading & descending stairs; head tilted toward side of damaged nucleus to compensate
97
What does the reticular formation in the brainstem do during sleep?
```
Midbrain raphe nuclei (seretonin)
Cereulean nucleus active in REM sleep
Hypothalamus metabolises CSF seretonin to produce sleep-inducing molecule
```
98
What does the reticular formation in the brainstem do when you're awake?
Cholinergic neurons adjacent to cerulean excite the cortex via the thalamus
Hypothalamic nucleus (tuberomammillary)
Basal nucleus of Meynert above optic chiasm also active
99
What are the different TMJ ligaments?
- Capsule
- Lateral ligament
- Sphenomandibular ligament
- Stylomandibular ligament
100
Where is the third ventricle?
In the midline between the two thalami
101
Damage to what area of the brain would cause hemi-spatial neglect?
Posterior parietal cortex (superior lobule), especially in right-sided damage
102
What is associative visual agnosia?
See object but do not recognise/distinguish
103
What is apperceptive visual agnosia?
Fail to perceive/see an object
104
What will happen if you have damage to Broca's area?
Expressive aphasia
| Content correct, but slow or missing words. Like trying to speak a language you’ve just started to learn
105
What will happen if you have damage to Wernicke's area?
```
Receptive aphasia (both auditory & reading)
Content incorrect, but speech fluent. Can speak fluently but it is nonsense but they don’t realise it’s nonsense.
```
106
What will happen if you have damage to Angular gyrus?
Alexia and agraphia (inability to read or write)
107
What will happen if you have damage to the primary auditory cortex?
Reduction of hearing sensitivity in both ears (mostly contralateral) & loss of stereo perception of sound origin
108
What is the blood supply to Broca's and Wernicke's area?
Middle Cerebral Artery
109
What will happen if you have damage to Arcuate Fasciculus?
Conductive aphasia - unable to repeat words.
110
What will happen if you have damage to corpus callosum's commissural fibres?
Split-brain symptoms:
Inability to NAME objects held in left hand
Inability to READ left half of visual fields
111
What artery supplies the leg section of primary motor cortex and primary somatosensory cortex?
Anterior Cerebral Artery
112
What artery supplies the hand and face section of the primary motor cortex and primary somatosensory cortex?
Middle Cerebral Artery
113
What arteries supply the basal ganglia section?
Striate and choroidal arteries
114
What arteries supply the choroid plexus and thalamus?
```
Anterior choroidal (from ICA)
Posterior choroidal (from PCA)
```
115
What else does the anterior choroidal artery supply?
Optic tract
Lateral geniculate body in thalamus (vision)
Posterior limb of internal capsule
Parts of limbic system
116
What forms the Papez circuit?
1) Hippocampus
2) Fornix
3) Mamillary bodies
4) Anterior thalamic nuclei
5) Cingulate gyrus
117
Where is the hippocampus found?
Inferomedial temporal lobe
118
What happens if you have damage to hippocampus?
Anterograde amnesia
No new memory formation
Still able to recall long term memories
Hippocampus is also involved in memories involving spatial/visual tasks + language
119
What is the anterior cingulate gyrus involved in?
```
Autonomic area:
Cardiorespiratory & digestion, visceral response to emotion
Bladder control
Emotional modulation of pain
```
120
What is the posterior cingulate gyrus involved in?
Vocal area controlling appropriate sentence construction
Memory, cognition
121
What nuclei are involved in reward?
Septal & Accumbens Nuclei
122
Which part of the brain is involved in recognising the emotional content of faces?
Amygdala
123
What can happen if you have bilateral damage of the amygdala?
Kluver-Bucy Syndrome
Docile, lack of fear/anger
Increased appetite
Hypersexual
Excessive exploratory behaviour w/mouth and hands
Visual agnosia
Memory disorders (lack of facial recognition)
124
Where do olfactory neurons travel to?
Orbital cortex and piriform cortex (part of temporal lobe)
125
What is the region of greatest visual acuity?
Fovea centralis (macula)
126
What are the three layers of the eye?
Retina (photo-receptive / sensory region)
Choroid (vascular)
Sclera (white outer layer)
127
Where is the blind spot?
Optic papilla
128
What will central retinal artery occlusion cause?
Blindness
129
What are Baum's loop and Meyer's loop?
Baum’s Loop --> Superior bundle of loop that arches upwards into parietal lobe)
Meyer’s Loop --> Inferior bundle of loop that arches down into temporal lobe
130
What is central scotoma?
Damage JUST your macular vision if you damage your occipital pole (TIP of striate area)
131
What three things make up accommodation?
- Vergeance
- Pupillary constriction
- Lens fattening
132
In lens fattening, does the ciliary body contract or relax?
The circumferential ciliary body contracts which then relaxes the suspensory ligaments – this allows the lens to recoil, relax, thus allows it to puff up (become fatter)
133
What is the sensory part of the cochlea?
Organ of Corti
134
How does the Organ of Corti allow you to hear?
Organ of Corti has sensory hair cells that detect vibrations. Vibrations transmitted from the perilymph to the endolymph through the vestibular membrane.
135
What can cause sensorineural deafness?
Drug linked, viral Rubella in utero, or mumps
136
What can cause loss of stereo-placement of sound?
Can indicate a cortical or thalamic issue/pathology
137
What can cause tinnitus?
Occurs in Méniere’s Disease, URTI, or following exposure to loud sounds
Tensor tympani / stapedius myoclonus (contractions) can cause tinnitus
138
What is the dynamic part of the vestibular system formed from and what does it do?
Formed from semi-circular canals & crista
Acts mainly on eye movements via medial-longitudinal fasciculus
139
What is the static part of the vestibular system formed from and what does it do?
```
Formed from maculae
(utricle & saccule)
Acts via vestibulospinal pathway
(3rd major descending pathway)
Pick up static changes of position of the head (even when it is still)
Pick up acceleration of your head
```
140
What type of acceleration does the utricle detect?
Detect horizontal acceleration (e.g. driving)
Active with head in flexion or extension
141
What type of acceleration does the saccule detect?
Detect vertical acceleration (e.g. falling)
Extensor activation in a fall (strong extensor thrust) –
as this activates the Vestibulospinal pathway
Active with head held to side
142
Where do the vestibular nuclei sit?
Pontomedullary brainstem
143
What are the 3 inputs to balance and how many can we lose?
- Vestibular
- Visual
- Proprioception
We can lose 1 of our inputs…but lose 2, and we become UNSTABLE…lose postural control!
144
What is Argyll-Robertson (prostitute's) pupil?
There is NO pupillary light reflex BUT the accommodation reflex/response is WORKING. Therefore, doesn’t use posterior part of brainstem, goes directly to EWN. This indicates there’s damage to brainstem
145
What happens with EWN damage?
No direct or consensual reflex on damaged side
Pupil dilated and unreactive
Cause: Vascular/tumour/brainstem
146
What happens with CN III compression?
No direct or consensual reflex on damaged side
Pupil dilated and unreactive
CNIII Compression = loss of all CNIII functions
CNIII Vascular lesion = sparing of pupillary functions
147
What is the innervation of orbicularis oculi?
CN VII
148
What is the innervation of superior tarsal?
sympathetic
149
What is Hering's law?
Extraocular muscles normally have equal and simultaneous innervation
150
What causes internuclear opthalmoplegia?
Internuclear opthalmoplegia results from lesions of the MLF
| (Cuts the interneuron connections between CNVI and CNIII)
151
When the head turns to the right, what happens to the eyes?
The right lateral semicircular canal is activated by axial head movement/rotation to the right. Makes both eyes look to the opposite side (left).
