Unit 3: Cerebellum Pg 102-112 Flashcards
Medial portion fo the cerebellum, extending from superior surface to inferior surface
Vermis
Paired structures of the cerebellum, lateral to the vermis
Hemispheres
The medial part of the hemispheres of the cerebellum is often referred to as the
Paravermis
What fissure is on the superior surface that separates anterior cerebellum from posterior cerebellum?
Primary fissure
What lobe is on the superior surface of the cerebellum and anterior to primary fissure?
Anterior lobe
What lobe is posterior to primary fissure and on the superior surface and extends into the inferior surface of the cerebellume?
Posterior lobe
Which lobe is located along the anterior edge of the inferior surface of the cerebellum?
Flocculonodular lobe
What are the lateral paired structures on the flocculonodular lobe
Flocculi
The flocculi are near what cranial nerves
VII
VIII
What structure is the midline part of the flocculonodular lobe?
Nodulus
The nodulus extends into what space?
IV ventricle
3 division of cerebellum
Archecerebellum
Paleocerebellum
Neocerebellum
The archicerebellum also called
Vestibulocerebellum
Paleocerebellum also called
Spinocerebellum
Neocerebellum also called
Pontocerebellum
What division of the cerebellum receives afferent input from vestibular nerve, vestibular nuclei and contralateral inferior olivary nucleus
Archicerebellum (vestibulocerebellum)
What division of the cerebellum receives much of its afferent input from sensory fibers that ascend from the spinal cord
Paleocerebellum (spinocerebellum)
What division of the cerebellum is the newest and largest part where input is largely from cerebral cortex after relay in pontine nuclei
Neocerebellum (pontocerebellum)
What division of the cerebellum corresponds anatomically to the flocculonodular lobe
Archicerebellum
What division of the cerebellum corresponds to (most of the) vermis and paravermis
Paleocerebellum
What division of the cerebellum corresponds to (a portion of) the vermis, but mostly the lateral portion of the hemispheres
Neocerebellum
Leif-like folds on the cerebellar cortex called
Folia
The surface area of the cerebellar cortex is about ____ the surface area of the cerebral cortex
3/4
Neurons in the cerebellar cortex include:
Purkinje **ONLY CEREBELLAR Golgi Stellate Basket Granule cells
What layer is the inner layer of the cerebellum called
Granular layer
The granular layer has this kind of neurons
Granule and Golgi cells
What do axons of granule cells do
Ascending into the molecular layer and interact with dendrites of Purkinje cells, which allow granule layer neurons to influence Purkinje cells
What is the middle layer of the cerebellum called
Purkinje layer
What layer is the Purkinje layer
Middle layer
What do dendrites do in the Purkinje layer?
Arborize in the molecular layer
Axons leave the cerebellar cortex and terminate on
deep cerebellar nuclei or the vestibular nuclear complex
Purkinje cells are the ONLY
Efferent neurons of cerebellar cortex
How many rows of purkinje cells/neurons and where are they?
Single row; middle layer
What is the outer layer in the cerebellum
Molecular layer
What are the number of neurons in the molecular layer?
Few
The molecular layer serves as a major ____ field
Synaptic
Molecular layer contains dendrites of
Purkinje cells
The white matter forms the
core/medullary center
Efferent fibers in the white matter are
exiting/leaving the cerebellum
Afferent fibers in the cerebellum are
Entering cerebellum
As white matter extends out to the cortex, it forms
Arbor vitae
Middle cerebellar peduncle only includes what fibers
Afferent pontocerebellar fibers
Superior cerebellar peduncle includes what tracts
Ventral spinocerebellar tract and others
Inferior cerebellar peduncle includes what tracts
Vestibulocerebellar tract
Dorsal spinocerebellar tract
Cuneocerebellar tract
Olivocerebellar tract
Afferent fibers form 2 structural types of fibers
Mossy fibers or climbing fibers
Mossy fibers terminate in the granular layer in an expanded terminal called a
rosette
Climbing fibers ascending into the molecular layer where they
Climbe dendritic trees of purkinje cells
Mossy fibers indirectly influence purkinje cells how?
mossy fibers synapse on golgi and gradual cells. Granule cell axons project into molecular layer and influence purkinje cells.
Climbing fibers directly influence purkinje cells how?
Climbing fibers project into the molecular layer and exert powerful control on purkinje cells
Climbing fibers are primarily ____ while mossy fibers include:
Olivocerebellar fibers; spinocerebellar fibers, cuneocerebellar fibers, pontocerebellar fibers, vestibulocerebellar
Central nuclei
Deep/subcritical cerebellar nuclei
4 pairs of nuclei embedded in medullary center
Fastigial nuc, globose nuc, emboliform nuc, dentate nuc
There are 2 sources of input into the central nuclei (4 pairs of nuclei embedded in medullary center). Most of the input come from
Purkinje cells of cerebellar cortex that provide strong inhibitory influence on cerebellar nuclei
There are 2 sources of input into the central nuclei (4 pairs of nuclei embedded in medullary center). Some of the input comes from
Sources outside the cerebellum. These fibers provide excitatory input to cerebellar nuclei
Pontocerebellar fibers Vestibulocerebellar fibers Spinocerebellar fibers Olivocerebellar fibers Others
Axons of central nuclei project efferent fibers out of cerebellum via
Inferior and superior cerebellar peduncles (no MCP)
Axons of central nuclei provide
FINAL efferent output of the cerebellum
In order for the cerebellum to influence motor activity, neurons of central nuclei must project fibers of the cerebellum to modify the activity of motor areas of the brain and brainstem and also to the motor nuclei of the thalamus.
Archecerebellum, also called:
Vestibulocerebellum
Archecerebellum
Anatomically:
Flocculonodular lobe
Paleocerebellum also called
Spinocerebellum
Paleocerebellum
Anatomically:
Vermis and paravermis
Neocerebellum, also called
Pontocerebellum
Neocerebellum
Anatomically:
Part of vermis and lateral portion of hemispheres
Efferent output of the archicerebellum is by the neurons of
fastigial nucleus and some into brainstem
I.e purkinje neurons of the cortex of the archicerebellum send axons
to the fastigial nucleus and some into the brainstem
The archicerebellum is involved in
Adjustment of muscle tone in response to vestibular data
Maintenance of equilibrium and eye position in response to movement of the head
Lesion of the flocculonodular lobe would result in
- Loss of equilibrium
- Loss of adjustment of muscle tone in response to vestibular data
- Inability to maintain proper eye position in response to head movements
Archicerebellum receives afferent input from the
- Vestibular nerve
- Vestibular nuclei
- Contralateral inferior olivary nucleus
Paleocerebellum receives afferent input from
- Dorsal and ventral spinocerebellar tracts
- Cuneocerebellar tract
- olivocerebellar tract
Remember: one side of paleocerebellum receives sensory input from the ipsilateral side of the body
Efferent output of the paleocerebellum is by the neurons of
- Fastigial
- Globose
- Emboliform nuclei
I.e. purkinje cells of the cortex of the paleocerebellum project axons
to the fastigial nucleus and the globose and emboliform nuclei
Fibers from globose and emboliform nuclei (paleo cerebellar output) traverse the SCP and terminate
- UMNs in reticular formation
- Reticulobulbar tract
- Ventral/anterior reticulospinal tract
- Lateral reticulospinal tract
Therefore the paleocerebellum receives input of proprioception and other sensory modalities and utilizes this information to influence motor output of vestibular nuclei, reticular formation (red nucleus and motor areas of cerebral cortex)
Paleocerebellum is involved in
- Control of muscle tone
- Synergy of muscle groups — coordination of muscle contracts especially in muscles used in postural control and gait
Neocerebellum receives afferent input from
- Contralateral cerebral cortex via corticospinal-ponto-cerebellar projections
- olivocerebellar projections
Note: input to pontocerebellum from cerebral cortex concerns movements that are planned and movements that are in process
Efferent output of the neocerebellum is by the neurons of
Dentate nucleus
I.e. purkinje cells of the neocerebellum project axons to the dentate nucleus
Neurons of dentate nucleus send fibers through SPC to
- Contralateral red nucleus and influence rubrospinal tract and rubrobulbar tract
- Most to contralateral ventral lateral nucleus of thalamus which influences the output of motor areas of cerebral cortex including
- corticospinal and corticobulbar/corticonuclear tracts
- corticovestibular tract
- corticoreticular tract
- corticopontine p/ways
- others
One hemisphere of the cerebellum exerts control over movements on the
Ipsilateral side of the body/face
Asyngergy
Loss of coordination
Asynergy affects muscles of
Axial skeleton/trunk
Proximal extremities, especially lower extremities
Ataxic gait
Wide-based, staggering gait
Unstable postures with lots of body sway
Nystagmus
Involuntary and repetitive eye movements
Disorders of movement include
Asynergy
Ataxic gait
Frequent nystagmus
Pathologies that affect the archicerebellum will usually result in degeneration of
Midline portions of cerebellum that affect vermis and flocculonodular lobe and thus disorder movement
Neocerebellar syndrom is associated with pathologies to the
Hemispheres
Neocerebellar syndrom includes interruption of
afferent input, efferent pathways, etc
Hypotonia
Decreased muscle tone
Ataxia
Movements lack coordination
Dysmetria
Difficulty gauging the appropriate distance, power, speed of a movements to desired target
May undershoot or overshoot target
Past-pointing
Difficulty finding a target
Intention tremor
Occurs at the end of a voluntary movement as the patient tries to correct for a defective movement to a target
Dysdiadochokinesia
Inability to perform rapid, alternating movements that are repetitive
Neocerebellar syndrome pathologies may include
Hypotonia
Ataxia
General asynergy; inappropriate force, range and direction of movement that may result in movements taking longer to initiate and to stop, dysmetria, past-pointing, intention tremor, ‘decomposition of a movement’ where movements are fragmented/disjointed, dysdiadochokinesia, disarthria
Disarthria
Slurred speech
archicerebellum – receives afferent input from…
vestibular ganglia
and nuclei
paleocerebellum - receives much of its afferent input from…
sensory fibers that ascend from the spinal cord
neocerebellum - receives input largely from….
the cerebral cortex after relay in the pontine nuclei.
climbing fibers are primarily olivocerebellar fibers that originate from the…
contralateral inferior olivary nuclear complex
archicerebellum influences motor control by modifying the activity of descending motor pathways that originate from the vestibular nuclei which includes what tracts?
vestibulospinal tract
descending MLF
ascending MLF
fibers from the fastigial nucleus (paleocerebellar and acrchicerebellar output) traverse the ICP, terminate in and influence the output of the vestibular nuclear complex, which includes:
- vestibulospinal tract
- MLF
