cerebellum Flashcards
The cerebellum is connected to the brainstem by three paired fiber bundles or peduncles:
the inferior, middle and superior cerebellar peduncles
The inferior and middle peduncles carry the major ________ to the cerebellum, and the superior peduncle contains the _______ .
inputs,
output
The flocculo-nodular lobe of the cerebellum is the phylogenetically oldest portion of the cerebellum, and is also referred to as the
_______.
archicerebellum
the posterior lobe of the cerebellum is evolutionarily most recent and most of it comprises what is referred to as the ______.
neocerebellum
The ______ refers to the midportion of the anterior lobe and the posterior lobe of the cerebellum
paleocerebellum
Thus the flocculo-nodular lobe (archicerebellum) is also called ______the since it receives input from the vestibular organs, and outputs to the vestibular nucleus in the brainstem.
vestibulocerebellum
the paleocerebellum is also called the ______ since it receives extensive input from spinal afferents, and outputs onto motor control nuclei (e.g., the red nucleus).
spinocerebellum
the cerebellum consists of a three-layered cortex overlying a group of paired central nuclei. There are four nuclei on each side, the : __________
dentate, globose and emboliform (together referred to as the nucleus interpositus or interposed nucleus)
and fastigial nuclei
The medial or vermal zone of the cerebellum has output connections through the _____ nucleus and is involved in control of axial musculature, posture and balance, and integration of head and eye movements
fastigial
the intermediate (or paravermal) zone has outputs through the ______ and fine-tunes movements of the limbs
interposed nuclei
while the lateral (or hemispheric) zone of the hemispheres has connections through the ______ nucleus and is involved in higher level coordination of movements, including planning and initiation of movements
dentate
The cerebellar outputs from the deep nuclei of the medial regions (vermis, vestibulocerebellum) , ultimately modulate these 3 medial descending pathways.
vestibulospinal tracts,
reticulospinal tracts,
tectospinal tracts
The cerebellar outputs from the lateral regions (paravermis and vestibulocerebellum) project to the dentate and interpositus nuclei, which ultimately modulate the rubrospinal and corticospinal outputs. These are responsible for the control of _______
fine, distal muscle movements
Cerebellar cortex has cells that recieve two distinct inputs:
one is modality-specific input (i.e. balance, limb position, eye-hand coordinates) that represents a copy of the reflex input called ________-
another input from the inferior olivary nucleus, hypothesized to signal errors- unexpected responses- in reflex activity called _________-
MOSSY FIBERS,
CLIMBING FIBERS
Axons from the cortex synapse on ipsilateral neurons in the ______ and the _____ neurons send axons contralaterally to the cerebellar hemispheres.
basal pons,
pontine
the medial cerebellum must be involved in functions of
______ and ________
EQUILIBRIUM (reflecting the interconnections with vestibular nuclei and descending spinal tracts),
POSTURE (recognizing the distribution of proprioceptive and cutaneous afferents from the axial musculature to this region).
Paravermal or intermediate cerebellum is concerned with the control of movement of the _____, and outflow goes to the _______ via the interposed nuclei
distal limbs,
red nucleus
Lateral cerebellum is less directly associated with particular body regions, but has extensive interconnections with motor cortex. This reflects the role of the neocerebellum in cortical coordination and ________-.
planning and initiation of movement
cerebellar lesions result in loss of ______ but no loss of sensation or muscle strength.
coordination (including equilibrium)
cerebellar deficits are always _______.
ipsilateral
what is past-pointing or dysmetria ?
inability to bring a limb to a required or desired point in space. ( due to lesions in cerebellum)
If the flocculo-nodular lobe is impaired, due for example to a medulloblastoma that is common in childhood, _____ is impaired but not coordination or muscle tone.
equilibrium
there is occasionally degeneration of the vermal cerebellum in alcoholism that results in ________
postural problems involving trunk muscles
Cerebellar deficits can be remembered with the mnemonic “HANDS Tremor” it stands for:
Hypotonia- mainly with anterior lobe injury
Ataxia- this means “without order” and includes the 3 “D”s
-dysdiadochokinesia- or impaired rapid alternating
movements
-decomposition of movement
-dysmetria- or “past pointing”
Nystagmus
Dysarthria
Stance and gait problems
Tremor- specifically, intention tremor. This involves increasing oscillation as the limb approaches a target, i.e. touching one’s nose
Climbing fibers come from the contralateral ______.
inferior olivary nucleus
______ fibers carry input to the cerebellar cortex from a wide variety of sources, including primary vestibular afferents and pontine nuclear cells
Mossy
The ascending axons of the ____ cells branch in a T-shaped manner to form the parallel fibres,
granule
With the exception of _____ cells, all cerebellar cortical neurons, including the Purkinje cells, make inhibitory synaptic connections with their target neurons.
granule
the only output from the cerebellar cortex is via the ______ cells
Purkinje
When the inferior olive detects a discrepancy between planned and actual motor performance it generates _________ activity (an error signal) that modulates cerebellar function, including long-term depression of sensitivity to mossy fiber input
climbing fiber
