Neuroanatomy 4 Flashcards
What separates the cerebellum from the occipital lobe?
Tentorium cerebelli
What connects the brainstem to the cerebellum?
The 3 pairs of cerebellar peduncles
Superior
Middle
Inferior
Where is the 4th ventricle?
Between the posterior pons and the medulla ventrally and the cerebellum dorsally
What lobes is the cerebellum divided into?
Anterior lobe
Posterior lobe (contains a horizontal fissure) (is larger)
Divided by the primary fissure
Flocculonodular lobe - most ventral
What does the primary fissure seprarate?
The anterior and posterior lobes of the cerebellum on either side
What is the flocculonodular lobe made up of?
The flocculus(beneath the cerebellar peduncles)
and the nodule(found in the midline)
What divides the 2 hemispheres of the cerebellum?
A midline structure called the vermis
What are the ‘gyri’ of the cerebellum called?
Folia - they are much smaller
Which lobe of the cerebellum is larger?
Posterior is larger than anterior
Flocculonodular is small as well
Where are the cerebellar tonsils located?
Beneath the middle cerebellar peduncles
What are the 3 functional areas of the cerebellum?
Spino-cerebellum
Cerebro-cerebellum
Vestibulo-cerebellum
For the spino-cerebellum what is the…
- anatomical part
- primary input
- cerebellar peduncle
- function
- Vermis
- spinocerebellar tracts
- superior and inferior peduncles
- correction and modulation of fine movements
For the cerebro-cerebellum what is the…
- anatomical part
- primary input
- cerebellar peduncle
- function
- Lateral hemispheres
- Cerebral cortex
- Middle peduncles
- Planning of coordinated movements
What is the function of…
- spino-cerebellum
- cerebro-cerebellum
- vestibulo-cerebellum
- correction and modulation of fine movements
- planning of coordinated movements
- balance, posture, tone and stabilisation of eye movements
For the vesetibulo-cerebellum what is the…
- anatomical part
- primary input
- cerebellar peduncle
- function
- flocculonodular lobe
- vestibular system (inner ear)
- inferior peduncle
- Balance, posture, tone and stabilisation of eye movements
Which 3 paired arteries supply the cerebellum?
Superior cerebellar arteries
Anterior inferior cerebellar arteries
Posterior inferior cerebellar arteries
All 3 also supply the brainstem
Where do the superior cerebellar arteries originate from?
Branch from the basilar artery just before it bifurcates into the posterior cerebral arteries
Where do the anterior inferior cerebellar arteries branch from?
Most inferior part of the basilar artery
Just after it forms from the vertebral arteries
Where do the posterior inferior cerebellar arteries originate from?
Branch from the vertebral arteries
Before they merge to form the basilar artery
What does VANISHED stand for in cerebellar dysfunction?
V- vertigo
A- ataxia
N- nystagmus
I- intention tremor
S- slurred speech
H- hypotonia
E- exaggerated past-pointing
D- dysdiadochokinesia
What is cerebellar dysfunction?
What can it be caused by?
How are the symptom’s remembered?
Disruption to the cerebellum’s functions
Heavy alcohol consumption, lesion of the cerebellum such as a stroke or a tumor
VANISHED
What does V stand for in VANISHED? (cerebellar dysfunction)
VERTIGO
cerebellar function involves processing large amount of info from vestibular system like sense of balance or perception of movement
What does A stand for in VANISHED? (cerebellar dysfunction)
ATAXIA
Means poor coordination
Observe the patient’s gait - may appear unstable with a very wide step to stabilise themselves
What does N stand for in VANISHED? (cerebellar dysfunction)
NYSTAGMUS
Refers to subtle, rapid, backwards-and-forwards eye movements observed when closely looking at a patient’s eyes
Small amount of horizontal nystagmus may be normal
Vertical or rotational nystagmus is almost always abnormal
The cerebellum stabilises eye movements
What does I stand for in VANISHED? (cerebellar dysfunction)
INTENTION TREMOR
Tremor caused by cerebellar region is absent at rest and appears when a patient ‘intends’ to do something e.g. move arms, pick up
Dysfunctional cerebellum unable to correct and modulate fine movements to stabilise
What does S stand for in VANISHED? (cerebellar dysfunction)
SLURRED SPEECH
Dysfunctional cerebellum unable to coordinate fine movements inc those used in articulation of speech
So patients may have slurred speech
What does H stand for in VANISHED? (cerebellar dysfunction)
HYPOTONIA
Lack of tone (muscles)
Dysfunctional cerebellum unable to maintain tone and posture (vestibulocerebellar)
What does E stand for in VANISHED? (cerebellar dysfunction)
EXAGGERATED PAST-POINTING
Ask the patient to touch their nose then reach out to touch the tip of your finger
Dysfunctional cerebellum unable to coordinate rapid correctional eye movements so patients often ‘overshoot’ your finger tip and ‘point past’ it
What does D stand for in VANISHED? (cerebellar dysfunction)
DYSDIADOCHOKINESIA
(DDK)
Ask patient to rapidly alternate between touching the palmar and dorsal parts of their fingers onto the opposite palm
Cerebellar dysfunction means can’t coordinate this smoothly and can’t rapidly pronate and supinate their forearms, or miss the arm entirely
What does VANISHED tell you about normal cerebellar functioning?
V - cerebellum helps in balance and coordination of movement
A - aids in coordination - stable gait
N - stabilises eye movements
I - corrects and modulates fine movements to stablise arm and hand
S - coordination of fine movements - inc muscles of speech
H - maintains tone and posture through vestibulocerebellum
E - performs rapid correctional movements
D - movements coordination - inc pronation and supination
What is the corpus callosum?
Primary connection between left and right hemispheres of the cerebrum
A group of commissural fibres
What are commissural fibres?
Fibres that cross the commissure into the opposite cerebrum
What are the midline structures of the brain?
Parts of the brain that are only visible when the brain is divided in the saggital plane - particularly part of the diencephalon e.g. thalamus, corpus callosum
What is the thalamus?
Part of diencephalon
Relay for numerous functions of the brain
Including motor, sensory, visual, auditory, cognitive, emotional pathways
What is the hypothalamus?
Immediately below the thalamus
Key to homeostasis
Controls numerous hormonal and endocrine functions and autonomic nervous system
What is the pituitary gland and what is its function?
Sits at end of a stalk (infundibulum), in the pituitary fossa of the sphenoid bone, optic chiasm is immediately superior to it
Involved in hormone secretion, often controlled by hypothalamus
What is the infundibulum?
Stalk that connects the pituitary gland to the brain
What is the pineal gland and what is its function?
Immediately posterior to the colliculi of the midbrain but part of the diencephalon
Secretes melatonin - controls sleep-wake cycle
What is the calcarine sulcus?
Sulcus separating the occipital lobe
Within it is the primary visual cortex
What structures are in the limbic system?
Fornix
Mammillary bodies
Hippocampus
Parahippocampal gyri
Cingulate gyrus and cingulate sulcus (cingulum)
Nucleus accumbens
Amygdala
Other - sections of the olfactory and insular cortex, thalamus and hypothalamus
What is the basic function of the limbic system?
Plays a significant role in many important functions such as leaning, memory, emotional control
What and where is the fornix?
What- White matter bundle that connects various structures in the limbic system esp hippocampus to mamillary bodies + anterior nuclei of thalamus
Where - similar in shape to but much smaller than the corpus callosum, rests over the thalamus
Part of the limbic system
What and where are the mamillary bodies?
What - nuclei (may be involved in relay?)
Where - small, round nuclei located at the anterior tip of the fornix
Part of the limbic system
What and where is the hippocampus?
What - integral in converting short-term to long-term memory
Where - in the temporal lobe
A more lateral structure, immediately inferior to the inferior horn of each lateral ventricle but closer to the is below the thalamus
Part of the limbic system
What and where are the parahippocampal gyri?
Gyri of the temporal cortices, located next to the hippocampi
Part of the limbic system
What is the cingulate gyrus and cingulate sulcus?
Large gyrus and associated sulcus - fibres that travel from here to the other parts of the limbic system are called the cingulum
Immediately superior to the corpus callosum on both sides of the cerebrum
Part of the limbic system
What are association fibres?
Fibres that connect different parts of the same hemisphere
What is the cingulum?
Fibres that travel from the cingulate gyrus to other parts of the limbic system
Namely the parahippocampal gyrus
A group of association fibres
Part of the limbic system
How is the limbic system involved in amnesia?
Esp the hippocampus, it is involved in memory formation and converting short-term to long-term
Head injury or disease that affects the limbic system may cause amnesia
Can be retrograde(can’t recall events prior) or anterograde amnesia (can’t create new memories after onset)
What is the function of the basal ganglia?
Group of deep nuclei in the brain
Contribute to coordination, control and inhibition of motor function (substantia nigra inhibits BG’s [or striatums?] inhibition to control initiation of movement)
Very complex excitatory and inhibitory pathways are between each nucleus of the basal ganglia
What is the basal ganglia made up of?
Parts throughout the cerebrum, diencephalon and midbrain…
For each nucleus there is a left and right
- Caudate nucleus
- Globus pallidus
- Putamen
- Substantia nigra
- Subthalamic nucleus
What are subsections within the basal ganglia?
lentiform nucleus - putamen and globus pallidus
striatum - caudate nucleus and lentiform nucleus
Which structures are considered anatomically to be part of the basal ganglia but not part of the motor function?
They contribute to the limbic system instead
- nucleus accumbens
- amygdala
What and where is the caudate nucleus?
What - c-shaped structure
Where - rests immediately medial to and follows the curvature of the lateral ventricle
Part of the basal ganglia
What and where is the globus pallidus?
Triangular shaped nucleus
Divided into an external and internal part
Lies immediately medial to the putamen
Part of the basal ganglia
What and where is the substantia nigra?
Black nucleus found in the midbrain
Produces dopamine
In the basal ganglia
What is the subthalamic nucleus?
Small nucleus located inferior to the thalamus, but superior to the substantia nigra
Part of the basal ganglia
What and where is the nucleus accumbens?
Where - anterior junction between the caudate nucleus and putamen
What - not a distinguishable structure, plays a role in reward systems and is a subject of research into addiction
Physiologically part of the limbic system, anatomically part of the basal ganglia
What and where is the amygdala
What - Small, spherical nucleus involved in memory and emotional responses such as fear and anxiety
Where - tip of inferior horn of caudate nucleus
What and where is the internal capsule?
What - bundle of white matter tracts, part of the route for majority of sensory and motor axons travelling to/from cortex
Projection fibres
Where - between thalamus and lentiform nucleus, look for ‘double V’ in transverse view
What are projection fibres?
Connect the cortex to deeper structures
What is the corona radiata?
Axons that pass from the internal capsule to the cortex form the corona radiata.
They ‘radiate’ out of the internal capsule towards the cortex
What causes Parkinson’s disease?
What are the symptoms?
Degeneration of the dopamine-producing neurons of the substantia nigra
Reduction of impulses passing within basal ganglia, impairs the initiation and inhibition of movement
‘Pill-rolling resting tremor most common
