CEREBELLUM Flashcards
he branching pattern of the white matter OF THE CEREBELLUM was referred to by early anatomists as the _______
arbor vitae
transverse fissures of the cerebellum
anterior and posterolateral or prenodular
e cortex of the vermis projects to the
______
that of the paravermis to the
and that of the cerebellar hemisphere to the dentate nucleus.
fastigial deep cerebellar nucleus
interposed deep nuclei (emboliform and globose),
________has reciprocal connections with vestibular and reticular nuclei and plays a role in control of body equilibrium and eye movement.
vestibulocerebellum (corresponds best with the flocculonodular lobe)
__________has reciprocal connections with the spinal cord and plays a role in control of muscle tone as well as axial and limb movements, such as those used in walking and swimming
The spinocerebellum (corresponds best to the anterior lobe)
_________has reciprocal connections with the cerebral cortex and plays a role in planning and initiation of movements, as well as the regulation of discrete limb movements.
The cerebrocerebellum or pontocerebellum (corresponds best to the posterior lobe)
In the _____, the body appears inverted, with hindlimbs represented rostral to the forelimbs and face.
anterior lobe of the cerebellum
layers of the cerebellar cortex
Outer molecular layer (about 300 µm in thickness)
Middle Purkinje cell layer (about 100 µm in thickness)
Innermost granule cell layer (about 200 µm in thickness)
cell types in each layer
Basket and stellate cells are in the molecular layer,
Purkinje cells are in the Purkinje cell layer,
and granule and Golgi cells are in the granule cell layer.
Purkinje cell
courses through the granule cell layer and deep white matter to project on deep cerebellar nuclei
Intrinsic neurons of the cerebellum
Basket cell
Stellate
Granule cell
Golgi II cell
Basket cells
situated in deeper parts of the molecular layer in close proximity to Purkinje cells.
______located in the superficial and deeper parts of the molecular layer.
Stellate cells
Difference between stellate and basket cells
The difference lies in the fact that stellate cells establish contact with the dendrites of Purkinje cells, whereas basket cells establish contact with dendrites, perikarya, and axons of Purkinje cells.
_______ are among the smallest cells in the brain (6 to 9 µm) and fill the granule cell layer.
Granule cells
________occupy the superficial part of the granule cell layer adjacent to the Purkinje cells. They are large neurons, about the same size as the Purkinje cell bodies.
GOLGI II CELLS
Axons of Golgi cells take part in the formation of the ______. They are characterized by a dense arborization of short axonal branches that span the entire granule cell layer
Glomerulus
They are the sites of synaptic contact between the incoming cerebellar fibers (mossy fiber system) and processes of neurons within the granule cell layer.
Glomerulus
Glomerulus
Cerebellar input via the mossy fiber system
Dendrites of granule cells
Axon terminals of Golgi neurons
Proximal parts of Golgi dendrites
The three major sources of afferents of the cerebellum:
are the spinal cord, vestibular system, and cerebral cortex.
Inputs from the spinal cord are transmitted to the cerebellum via the :________
These tracts provide the cerebellum with information related to the position and condition of muscles, tendons, and joints.
dorsal and ventral spinocerebellar tracts and the rostral extension of the dorsal spinocerebellar tract, the cuneocerebellar tract.
___________provide information related to body equilibrium.
Vestibulocerebellar inputs
Cortical inputs to the cerebellum originate in:
This is for planning and initiation of movement
neocortical as well as paleocortical and archicortical areas.
Other inputs:
________ (A-6 cell group of primates), a dopaminergic projection from the ventral tegmental area of Tsai in the midbrain (A-10 cell group of primates)
_______projection from the raphe nuclei (B-5 and B-6 cell groups of primates) in the brain stem.
locus ceruleus
serotonergic
TRACTS FROM TO THE CEREBELLUM VIA ICP:
- Dorsal spinocerebellar tract _____
- Cuneocerebellar tract _______
- Olivocerebellar tract ________
- Reticulocerebellar tract _________
- Vestibulocerebellar tract _____
- Arcuatocerebellar tract ________
7/ Trigeminocerebellar tract _____
- from the dorsal nucleus of Clarke
- from the accessory cuneate nuclei
- from the inferior olivary nuclei (major component)
- from the reticular nuclei of the brain stem
- (both primary afferents from the vestibular end organ and secondary afferents from the vestibular nuclei)
- from the arcuate nuclei of the medulla
- From the spinal and main sensory nuclei of the trigeminal nerve
fiber tracts to cereb via MCP
Pontocerebellar
Serotonergic fibers from the raphe nuclei
tracts into cerebellum via Superior Cerebellar Peduncle
Ventral spinocerebellar tract
Trigeminocerebellar tract from the mesencephalic trigeminal nucleus
Cerulocerebellar tract from the nucleus ceruleus
Tectocerebellar tract from the superior and inferior colliculi
It is generally believed that the _______is the major component of the climbing motor system.
olivocerebellar tract
Stimulation of the climbing fiber system elicits a ________ from the Purkinje cell capable of overriding any ongoing activity in that cell.
prolonged burst of high-frequency action potentials (complex spike)
The _______ includes all afferents to the cerebellum except those which contribute to the climbing fibers and the multilayered fiber system
mossy fiber system
This recently described fiber system includes afferents to the cerebellum from the hypothalamus, as well as the serotonergic input from the raphe nuclei, the noradrenergic input from the nucleus locus ceruleus, and the dopaminergic input from the mesencephalic dopaminergic neurons
MULTILAYERED FIBER SYSTEM
Similar to the climbing and mossy fiber systems, the multilayered fiber system projects on neurons in the_____
cerebellar cortex and the deep cerebellar nuclei.
The _______ is composed of multipolar neurons and resembles the inferior olive in configuration
The dentate nucleus
DENTATE NUCLEUS:
The _______ input is inhibitory, whereas the inputs from ______ are excitatory to the dentate nucleus
Purkinje cell
Climbing and mossy
The bulk of axons of the dentate nucleus project via the superior cerebellar peduncle (brachium conjunctivum) to the____________
to the contralateral ventrolateral nucleus of the thalamus.
The interposed nuclei receive afferent fibers from the following sources (Figure 15-19):
Axons of Purkinje cells in the paravermal (intermediate) zone of the cerebellum that are inhibitory in function
Collaterals from climbing and mossy fiber systems that are excitatory in function
Axons of interposed nuclei leave the cerebellum via the:
superior cerebellar peduncle (brachium conjunctivum).
This nucleus is located in the roof of the fourth ventricle medial to the globose nucleus; hence it is called the roof nucleus
Fastigial Nucleus
Fastigial Nucleus receives afferent fibers from the following sources
Axons of Purkinje cells in the vermis of the cerebellum that are inhibitory in function
Collaterals of mossy and climbing fiber systems that are excitatory
The cerebral cortex communicates with the cerebellum via the:
Corticoolivocerebellar via the red nucleus and inferior olivary nucleus
Corticopontocerebellar via the pontine nuclei
Corticoreticulocerebellar via the reticular nuclei of the brain stem
cerebellum influences the cerebrum mainly via _________
the dentatothalamic system.
he following neurotransmitters have been identified in the cerebellum:
gamma-aminobutyric acid (GABA): Inh
taurine: Inh of the superficial stellate cells
glutamate: excitatory neurotransmitter of granule cells
aspartate; xcitatory neurotransmitter in climbing and mossy fibers
acetylcholine: granule cells, Golgi cells, and mossy fibers
norepinephrine: inhibitory neurotransmitter of the locus ceruleus projection on Purkinje cell dendrites.
serotonin, and
dopamine
Cerebellar neurons are characterized by _____ of resting impulse discharge.
high rates
Stimulation of the mossy fiber system or of the parallel fibers (axons of granule cells) elicits in the Purkinje cell a brief ________followed by a prolonged ________
excitatory postsynaptic potential (EPSP) (simple spike) lasting 5 to 10 ms,
inhibitory postsynaptic potential (IPSP).
Stimulation of the climbing fiber system elicits in the Purkinje cell an intense and prolonged reaction characterized by an initial large spike followed by several small ones. This is called:
complex spike
A delay in the initiation of each successive movement will lead to the _________
adiadochokinesis (disturbance in performance of rapid movement using antagonistic muscle groups) of cerebellar disease.
A delay in the termination of movement results in_____
dysmetria
Thus, ___________are the result of an error in timing.
adiadochokinesis and dysmetria
__________ is due to defective feedback control from the cerebellum on cortically initiated movement
Intention (volitional) tremor
The cerebellum also influences movement via its effects on the_________. The cerebellum normally increases the sensitivity of muscle spindles to stretch.
gamma system.
The archicerebellum and paleocerebellum influence spinal activity via the
vestibulospinal and reticulospinal tracts.
Archicerebellar signs are usually associated with lesions in the flocculonodular lobe and are manifested by :
truncal ataxia (staggering gait and unsteady posture while standing)
and nystagmus (rhythmic oscillation of the eyes at rest and/or with ocular movements
The increase in myotatic and postural reflexes associated with the anterior lobe syndrome is due to an increase in motor signals to the ______ neurons and a simultaneous decrease in signals to the ____
Alpha
gamma system.
The objective of ___________ is to reduce the slip of a visual image over the fovea to velocities slow enough to allow clear vision.
smooth pursuit eye movements
_________and the ________to which it projects are necessary for horizontal saccades and make them fast, accurate, and consistent.
posterior lobe vermis (oculomotor vermis)
caudal nucleus fastigii
Damage to the ______ has been shown to impair rapid and accurate mental shifts of attention between and within sensory modalities
cerebellum
Non-motor fn of archicerebellum
Primitive autonomic responses, emotion, affect, sexuality, affectively important memory (“limbic” cerebellum)
Non-motor fn of Neocerebellum
Modulation of thought, planning, strategy formation, spatial and temporal parameters, learning, memory, language
_________may serve a modulatory role for emotional reactions
fastigial nucleus
The cerebellum is supplied by three long circumferential arteries arising from the vertebral basilar system:
(1) the posterior inferior cerebellar artery (PICA), (2) the anterior inferior cerebellar artery (AICA), and (3) the superior cerebellar artery (SCA).
posterior inferior cerebellar artery (PICA) arises from the rostral end of the vertebral artery and supplies the:
inferior surface of the cerebellum , including the cerebellar hemispheres, inferior vermis, and the tonsils. It also supplies the choroid plexus of the fourth ventricle and gives collaterals from its medial branch to supply the dorsolateral medulla.
anterior inferior cerebellar artery (AICA) arises from the caudal third of the basilar artery. Because of its usual small size, it supplies _______
a small area of the anterolateral part of the inferior surface of the cerebellum
When there is a large AICA, ________ hypoplastic, and the AICA territory then encompasses the whole anteroinferior aspect of the cerebellum.
the ipsilateral PICA
________is the most constant in caliber and territory of supply.
SCA
the SCA supplies most of the superior surface of the cerebellar hemisphere and vermis
The cerebellum is drained by three veins: superior, posterior, and anterior.
superior, empties into the great cerebral vein of Galen
posterior: empties into the straight or transverse sinus
anterior (petrosal): empties into the superior or inferior petrosal sinus.
