p.6
Nystagmus and Ocular Manifestations
What is downbeat nystagmus?
A pathologic upward drift of gaze followed by a corrective downward saccade.
p.14
Clinical Findings of Cerebellar Disorders
What does a normal result in the Finger-Nose-Finger test indicate?
It indicates normal coordination and the absence of appendicular ataxia.
p.16
Cerebellar Peduncles and Input/Output Pathways
What is the primary function of spinocerebellar pathways?
To convey proprioceptive information from the spinal cord to the cerebellum.
p.11
Vestibulo-Ocular Reflex (VOR)
How do the eyes move to maintain visual fixation during head movement?
The eyes move in the opposite direction of the head movement.
p.10
Cerebellum Structure and Function
What does the mnemonic 'Don't Eat Greasy Food' stand for in the context of cerebellar nuclei?
Emboliform, Globose, Dentate, Fastigial
p.9
Cerebellar Cortex Layers and Cell Types
What types of sensory information does the cerebellar cortex receive?
Vestibular, visual, auditory, and somatosensory information.
p.2
Cerebellum Structure and Function
What types of input does the cerebellum integrate to achieve motor planning and coordination?
The cerebellum integrates input from the cerebral cortex, multiple sensory modalities (vestibular, visual, auditory, somatosensory), brainstem nuclei, and spinal cord.
p.4
Cerebellar Peduncles and Input/Output Pathways
What is the superior medullary velum?
A thin layer of white matter that forms the roof of the fourth ventricle.
p.7
Cerebellar Peduncles and Input/Output Pathways
Where does the Superior Cerebellar Peduncle (SCP) send output?
To the red nucleus (midbrain) and thalamus.
p.4
Chiari I Malformation and Its Effects
What happens when the medulla is compressed due to tonsil herniation?
It can lead to eye movement problems, cervicospinal cord compression, and respiratory center dysfunction.
p.18
Cerebellar Cortex Layers and Cell Types
What is the role of granule cell axons in the cerebellar cortex?
They project to the molecular layer.
p.15
Cerebellum Structure and Function
What is the role of the cerebellar output from the interposed nuclei?
Control of ipsilateral distal limbs coordination.
p.15
Cerebellar Peduncles and Input/Output Pathways
What is the significance of the VL of the thalamus in cerebellar output?
It is a relay station for signals from the cerebellum to the motor/association cortex.
p.8
Cerebellar Peduncles and Input/Output Pathways
What are the main structures that the pons interacts with?
Red nucleus, cerebral cortex, brainstem nuclei, spinal cord.
p.17
Nystagmus and Ocular Manifestations
What is Brun's nystagmus?
A type of nystagmus most commonly associated with acoustic neuroma.
p.3
Cerebellum Structure and Function
What is the function of the vermis in the cerebellum?
Proximal limb and trunk coordination.
p.11
Vestibulo-Ocular Reflex (VOR)
What is the Vestibulo-Ocular Reflex (VOR)?
A gaze-stabilizing reflex during head movement.
p.3
Cerebellum Structure and Function
What are the functions of the flocculonodular lobe in the cerebellum?
Vestibular functions, including body balance and involuntary eye movement.
p.9
Cerebellar Cortex Layers and Cell Types
What is the role of Purkinje cell axons in the cerebellar cortex?
They carry the output from the cerebellar cortex to the cerebellar nuclei, which then send output to other regions.
p.2
Basal Ganglia and Cerebellum Interaction
How do the basal ganglia and cerebellum modulate motor output?
They modulate the corticospinal output and other descending motor systems through their respective feedback circuits.
p.2
Cerebellar Lesions and Ataxia
What are the consequences of cerebellum lesions?
Cerebellum lesions cause disorders in coordination and balance, often referred to as ataxia.
p.4
Cerebellar Peduncles and Input/Output Pathways
What is the posterior or inferior medullary velum?
A thin layer of tissue that forms part of the roof of the fourth ventricle.
p.4
Chiari I Malformation and Its Effects
What are the consequences of tonsil herniation?
Causes eye movement problems, medulla compression, cervicospinal cord compression, and affects the respiratory center.
p.1
Supratentorial and Infratentorial Anatomy
What anatomical regions are included in the infratentorial area?
The brainstem and cerebellum.
p.14
Clinical Findings of Cerebellar Disorders
What is the Finger-Nose-Finger test used to assess?
It is used to assess coordination and detect appendicular ataxia.
p.3
Cerebellum Structure and Function
What is the role of the intermediate hemisphere of the cerebellum?
Distal limb coordination.
p.16
Cerebellar Peduncles and Input/Output Pathways
What other types of inputs go to the cerebellum besides spinocerebellar pathways?
Various sensory and motor inputs.
p.9
Cerebellar Peduncles and Input/Output Pathways
From which nucleus do climbing fibers originate?
The inferior olivary nucleus.
p.7
Cerebellar Peduncles and Input/Output Pathways
What are the three main sources of input to the Inferior Cerebellar Peduncle (ICP)?
1. Inferior olivary nucleus (motor learning)
2. Spinal cord (where the body is)
3. Vestibular nuclei (where the head is)
p.18
Cerebellar Cortex Layers and Cell Types
What are the three layers of the cerebellar cortex?
Granule layer, Purkinje layer, Molecular layer.
p.7
Cerebellar Peduncles and Input/Output Pathways
Describe the pathway of Corticopontocerebellar fibers.
Cerebral cortex → anterior pons (pontine nuclei) → cross the midline in the anterior pons → contralateral cerebellum via the middle CP.
p.5
Chiari I Malformation and Its Effects
What is Chiari I malformation?
Cerebellar tonsils herniate through the foramen magnum due to a mismatch between the size and the content in the posterior fossa.
p.5
Nystagmus and Ocular Manifestations
What is oscillopsia?
An 'oscillating' or moving environment.
p.6
Nystagmus and Ocular Manifestations
Where does downbeat nystagmus localize the lesion to?
The cervicomedullary junction.
p.8
Cerebellum Structure and Function
What is the role of the pons in movement?
It gets input from the center and corrects movements as we're moving.
p.16
Cerebellar Peduncles and Input/Output Pathways
Do spinocerebellar pathways require detailed knowledge for basic understanding?
No, detailed knowledge is not necessary.
p.11
Vestibulo-Ocular Reflex (VOR)
What system provides the signals for the Vestibulo-Ocular Reflex (VOR)?
The vestibular system in the inner ear.
p.9
Cerebellar Peduncles and Input/Output Pathways
From which regions do mossy fibers originate?
Many regions, including brainstem nuclei and spinal cord nuclei.
p.9
Cerebellar Peduncles and Input/Output Pathways
Where do most fibers from the flocculonodular lobe project?
To the vestibular nuclei located in the brainstem, with a small amount projecting to the fastigial nuclei.
p.7
Cerebellar Peduncles and Input/Output Pathways
What type of output does the Inferior Cerebellar Peduncle (ICP) contain?
Output from the cerebellum to the vestibular nuclei.
p.7
Cerebellar Peduncles and Input/Output Pathways
What is the primary source of input to the Middle Cerebellar Peduncle (MCP)?
Pontine nuclei (what the brain wants to do).
p.18
Cerebellar Cortex Layers and Cell Types
What type of cells are found in the molecular layer of the cerebellar cortex?
Interneurons (stellate and basket cells).
p.5
Nystagmus and Ocular Manifestations
What are the ocular manifestations of Chiari I malformation?
Nystagmus (down-beat most common), sixth nerve palsy, papilledema, comitant esotropia.
p.5
Chiari I Malformation and Its Effects
Why does Chiari I malformation occur?
The posterior fossa is too small to hold the cerebellum and brainstem, causing the brainstem to descend out of the foramen magnum.
p.18
Cerebellar Cortex Layers and Cell Types
What are the components of the molecular layer in the cerebellar cortex?
Purkinje cell dendrites and interneurons (stellate and basket cells).
p.5
Nystagmus and Ocular Manifestations
What is nystagmus?
Repetitive, uncontrolled eye movements.
p.15
Cerebellar Peduncles and Input/Output Pathways
What does SCP stand for in the context of cerebellar output?
Superior Cerebellar Peduncle.
p.5
Nystagmus and Ocular Manifestations
Describe the phases of nystagmus in Chiari I malformation.
Slow phase: drifting up; Fast phase: fixation on downbeat.
p.15
Cerebellar Peduncles and Input/Output Pathways
Where does the SCP decussate?
At the midbrain, at the level of the inferior colliculus.
p.13
Clinical Findings of Cerebellar Disorders
What are the clinical features of truncal ataxia?
Wide-based, unsteady, 'drunk-like' gait, often unable to stand with their feet together with their eyes open.
p.13
Clinical Findings of Cerebellar Disorders
What symptoms are associated with lesions in the flocculonodular lobe?
Nystagmus, often associated with vertigo, nausea, and vomiting, due to its connection to the vestibular system.
p.12
Cerebellum Structure and Function
What cerebellar regions are involved in motor execution and somatic motor coordination?
Intermediate hemispheres (distal limbs) and vermis (trunk)
p.12
Cerebellum Structure and Function
What is the primary function of the lateral hemisphere in the cerebellum?
Motor planning and programming
p.18
Cerebellar Cortex Layers and Cell Types
What is a key feature of Purkinje cells in the cerebellar cortex?
They have extensive dendritic trees that extend into the molecular layer.
p.15
Cerebellar Peduncles and Input/Output Pathways
What pathway does the cerebellar output from the interposed nuclei follow?
SCP → VL of thalamus → motor/association cortex → lateral corticospinal tract.
p.13
Clinical Findings of Cerebellar Disorders
What tests are used to diagnose appendicular ataxia?
Abnormal 'finger-nose-finger' test or 'heel-shin' test; ataxia ipsilateral to the lesion.
p.13
Clinical Findings of Cerebellar Disorders
What speech problems can cerebellar lesions cause?
Scanning or explosive speech (irregular fluctuations in rate and volume) or slurred speech as in alcohol intoxication.
p.13
Clinical Findings of Cerebellar Disorders
What is ataxia?
Incoordination of movements.
p.15
Cerebellum Structure and Function
What is the lateral corticospinal tract responsible for?
It is involved in the control of voluntary movements, particularly of the distal limbs.
p.5
Chiari I Malformation and Its Effects
What is the purpose of surgery in Chiari I malformation?
To save the patient's life.
p.19
Cerebellar Peduncles and Input/Output Pathways
What nuclei do pontine nuclei and others project to?
Deep cerebellar nuclei & vestibular nuclei
p.19
Cerebellar Peduncles and Input/Output Pathways
What is the role of the inferior olivary nucleus?
Provides climbing fibers to the cerebellum
p.12
Nystagmus and Ocular Manifestations
Which cerebellar structures are responsible for eye movements such as saccades and smooth pursuit?
Vermis and intrinsic nuclei (e.g., fastigial nucleus)
p.12
Vestibulo-Ocular Reflex (VOR)
What is the function of the flocculonodular lobe in the cerebellum?
Control of vestibular functions, including body balance and the vestibulo-ocular reflex
p.15
Cerebellar Peduncles and Input/Output Pathways
What does 'double crossed' refer to in the context of cerebellar output?
The pathway crosses twice: once at the SCP decussation in the midbrain and once at the pyramidal decussation.
p.15
Cerebellar Peduncles and Input/Output Pathways
Where does the corticospinal tract cross?
At the pyramidal decussation.
p.13
Clinical Findings of Cerebellar Disorders
Why are careful neurological exams and neuro-imaging needed for differentiation of cerebellar disorders?
Because symptoms like nystagmus and ataxia are not necessarily specific to the cerebellum and can arise from other causes such as brainstem lesions or impaired proprioception.
p.12
Cerebellum Structure and Function
What is the role of the intermediate hemisphere in the cerebellum?
Motor execution, particularly for distal limbs
p.19
Cerebellar Cortex Layers and Cell Types
What cells do parallel fibers interact with?
Basket and stellate cells
p.13
Clinical Findings of Cerebellar Disorders
What type of deficits do unilateral cerebellar lesions cause?
Ipsilateral deficits because the cerebellar input/output pathways are either ipsilateral or double crossed.
p.12
Cerebellum Structure and Function
What are the main functions of the vermis in the cerebellum?
Motor execution (trunk coordination) and eye movements
p.8
Cerebellar Lesions and Ataxia
What is ataxia?
A condition characterized by balance problems and ocular movement problems.
p.17
Nystagmus and Ocular Manifestations
How does Brun's nystagmus present in terms of eye movement?
It has a fast beat in one gaze/direction and a slower beat in another gaze/direction.
p.3
Cerebellum Structure and Function
What function does the lateral hemisphere of the cerebellum serve?
Motor planning for extremities.
p.11
Vestibulo-Ocular Reflex (VOR)
Which parts of the cerebellum mediate the Vestibulo-Ocular Reflex (VOR)?
The flocculus and nodulus, the vestibular portion of the cerebellum.
p.2
Basal Ganglia and Cerebellum Interaction
Do the basal ganglia and cerebellum directly project to the lower motor neurons?
No, they do not directly project to the lower motor neurons.
p.10
Cerebellar Peduncles and Input/Output Pathways
How are all outputs from the cerebellum conveyed?
By the 4 deep cerebellar nuclei (roof nuclei) or vestibular nuclei (located in the brainstem)
p.4
Cerebellar Peduncles and Input/Output Pathways
What is the median aperture?
An opening in the brain that allows cerebrospinal fluid to flow from the fourth ventricle into the subarachnoid space.
p.4
Cerebellum Structure and Function
What is the arbor vitae?
The cerebellar white matter, named for its tree-like appearance.
