Flashcards in Tracts, basal ganglia and brainstem Deck (49):
Give 3 lower motor neurone lesion signs.
No Babinski sign
Give 3 (non-initial) upper motor neurone signs.
Hypertonia - spasticity
Positive Babinski sign
How does a UMN lesion initially present?
What is the internal capsule?
White matter carrying descending motor fibres from cortex.
It is found between the thalamus and caudate on one side and the globus pallidus and putamen on the other.
The fibres within it are not randomly arranged.
- Genu = head & face fibres (corticonuclear)
- Posterior limb = corticospinal tract fibres
What is the blood supply to the internal capsule?
Lenticulostriate arteries of the MCA
Why do UMN lesions lead to spasticity?
Loss of descending inhibition on LMN
What is the triad of signs characteristic of Parkinson's disease?
Tremor, rigidity, bradykinesia
Which basal ganglia is affected by Parkinson's
Substantia nigra pars compacta
What is the treatment for Parkinson's?
+ CARBIDOPA (to inhibit L-DOPA => dopamine in the periphery)
What do we give Parkinson's patient carbidopa as well as L-DOPA?
Because if don't give carbidopa, lots of the L-DOPA given would be converted to dopamine in the periphery. But we need dopamine in the brain! So inhibit peripheral conversion by AADC by giving carbidopa.
What is the red nucleus?
Important landmark in the midbrain it is involved in MOTOR control.
(without it, coarse tremour)
What are the crus cerebri?
- Mickey's ears
- Midbrain structures.
- Part of the cerebral peduncle containing descending motor fibres.
- Join cerebrum to midbrain.
What forms Mickey's nose?
The occulomotor nucleus.
- contains cell bodies of LMNs that travel CN3 to the eyeball
What is the superior colliculus?
Involved in reflex actions relating to the visual system.
What is the inferior colliculus?
Structure involved in reflex actions relating to the auditory system.
What is the periaqueductal grey matter?
Also called central grey matter
Important role in pain regulation and micturition.
In the internal capsule where would the fibres representing the lower limbs be found?
Posterior limb of internal capsule
The corticospinal tract has different names as it travels from cortex to periphery. What are these names?
1. Corona radiata
2. Internal capsule
3. Cerebral peduncles
4. Corticospinal tract
What is the corticobulbar tract?
It is a motor pathway from cortex to medullary pyramids.
It carries the UMNs (motor functions) of Cranial Nerves EXCEPT CN3.
(ie. as opposed to corticospinal which connects with spinal nerves)
What is spinal shock?
It describes the initial flaccid paralysis and hyporeflexia resulting from a UMN lesion.
=> signs of spinal shock can make one think it's a LMN lesion!
What is Cushing's reflex? (triad)
It is a physiological response to raised ICP.
1. Increased BP
3. Decreased RR
On a stroke ward a patient has only eaten the right half of his dinner. What is this called?
Which lobe is most likely affected in a patient showing signs of neglect?
Parietal. Because the parietal lobe is responsible for spatial awareness, directing attention to the external world.
Are the visual fields affected in neglect?
No. visual fields are intact
Patient experiences the smell of organise before a seizure, where is the causative lesion most likely to be?
Patient has tumour in left temporal lobe resected. Which vial defect might result?
Right superior homonymous quadrantanopia.
What is Broca's area responsible for?
Production of speech
What is Wernicke's area responsible for?
What is the name of the structure linking Wernicke's to Broca's?
How does a Broca's aphasia present?
Stoccato speech. Able to understand question and reply but difficult to produce speech.
How does Wernicke's aphasia present?
Lots of non-sense. Able to speak lots of words, but cannot answer a question as cannot understand speech.
In which lobe does Broca's area sit?
Frontal lobe of dominant hemisphere (left ++)
In which lobe does Wernicke's area sit?
Temporal lobe of dominant hemisphere (left ++)
What is implicit memory?
Memory for unconsciously mediated behaviours such as complex motor tasks (playing guitar, driving).
Which brain structure is crucial for consolidation of implicit memory?
What structure can uncial herniation compress?
What clinical sign of uncial herniation might we see?
Pupillary dilation (lost parasympathetic, so unopposed sympathetic)
Which 3 CNS herniations can occur when ICP is raised?
1. Uncal (transtentorial)
What is tonsillar herniation?
When the cerebellar tonsils are pushed downwards through the foramen magnum.
Increased pressure on the brainstem can result in dysfunction of the centers in the brain responsible for controlling respiratory and cardiac function
What is a subfalcine herniation?
The innermost part of the frontal lobe (cingulate gyrus) is pushed under part of the falx cerebri.
Rapid onset dementia in a young person might be suggestive of which condition?
What type of dementia presents with Parkinsonian features?
What is Pick's disease?
It is the formation of Pick's bodies from Tau proteins especially in frontal and temporal lobes
Name 2 microscopical features of Alzheimer's
1. Amyloid beta plaques
2. Neurofibrillary tangles
Infarcts affecting which vessel tend to cause pure motor strokes?
a Lenticulostriate stroke
Infarcts affecting which vessel tend to cause locked-in syndrome?
What two structures does the posterior communicating artery connect?
Posterior circulation (PCA) to Anterior circulation (ICA/MCA)
What two vessels are joined up by the anterior communicating artery?
Anterior cerebral arteries