Term
| functions of the cerebellum |
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Definition
| plans and fine tunes motor functions |
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Term
| topographical arrangement of cerebellum and their respective functions |
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Definition
Vermis: trunk and proximal muscles
Intermediate hemisphere: distal limb movement
Lateral hemisphere: motor planing and rehearsal of skilled movements
Flocculonodular lobe: (vestibulocerebellum) balance and vestibulo-occular reflexes |
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Term
| What is the major pathway influenced by the cerebellum |
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Definition
| Upper motor neurons; Lateral corticospinal tract |
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Term
| Spinocerebellar Pathway brings information about what and how? |
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Definition
| Mossy fibers influence the lateral hemisphere by updating the cerebellum cortex about an ongoing movement |
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Term
| Input Pathways: how do they enter the cerebellum and what are they bringing |
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Definition
| (enter cerebellum through the inferior and middle peduncles); all are excitatory; provide info on motor plan (from motor cortex) and what is occurring on in the muscles (proprioception) |
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Term
| What does the Spinocerebellar Pathway rbing to the cerebellum |
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Definition
| update about ongoing execution to vermis and intermediate hemisphere, |
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Term
| 2. Cerebrocerebellum Pathway brings |
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Definition
| Motor plan to the lateral hemisphere; i. Pontocerebellar fibers form the pontine nuclei in the motor cortex |
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Term
| 3. Inferior Olivary Nucleus brings |
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Definition
| i. project from Inferior Olivary neurons; ION receive all aspects of motor function; provide a monosynaptic powerful input onto Purkije fibers; GOAL: influence Purkinje fibers |
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Term
| Output pathway and fate of cerebellum influence |
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Definition
| 1. Superior Peduncle is the only exit rout of the cerebellum cortex; these axons dive down into the brainstem and cross the midline in the midbrain; then relay information to the VA/VL motor nuclei of the thalamus; Thalamus coneys info to UMNs; UMNS send info to corticospinal tract that crosses the midline at the pyramidal dessucation; |
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Term
| Nucleus of the Thalamus where the axons of the cerebellum syanpse |
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Definition
| Main outout target is Ventrolateral nucleus of thalamus |
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Term
| 1. Unilateral lesion of the cerebellum: |
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Definition
| may result in deficits in skeletal muscle performance that are ipsilateral to the side of the lesion; A patient may fall toward the side of the lesioned cerebellum |
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Term
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Definition
| difficulaty maintaining posture or balance; pt will have an cerebellar ataxic gait; vermis fine tunes axial muscles and proximal muscles; most importantly the thigh muscles! |
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Term
| 3. Cerebellar hemisphere lesions: (3 clinical symptoms) |
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Definition
i. Tremor with movement: tremor increases as target gets closer; no tremor at rest
ii. Dysmetria: difficulty measuring distance of target from the body; difficulty performing finger to nose test
iii. Dysdiadochokinesis: decrease ability to perform rapidly alternating movements; test: supination and pronation of the forearm, with slapping the anterior thigh between the movements |
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Term
| 4. Lesions in the Flocculonodular lobe: |
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Definition
| scanning dysarthria: break up words into individual syllables, disrupting the melody of speech; and they have abnormal conjugate gaze: they may pass the target, stop too soon, and oscillate a few times before they settle on the target. |
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Term
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Definition
| involved in cortol of balance eye movements, most of the inputs are from central processes of the vestibula nerve and from vestibular nuclei |
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Term
| What are the two Spinocerebellar tracts: |
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Definition
| Dorsal Spinocerebellar tract and the Cuneocerebellar tract |
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Term
| a. Dorsal Spinocerebellar tract brings what to the cerebellum; What is the location of the cell bodies (where do the axons project from)? |
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Definition
| Lower Limb proprioceptors; project from Clark’s nucleus (located in Laminae VII, intermediate zone) GOAL: influence Purkinje fibers |
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Term
| b. Cuneocerebellar tract: brings what type of information to the cerebellum and where does its axons project from? |
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Definition
| Upper limb proprioceptors; project from External Cuneate nucleus; GOAL: influence Purkinje fibers |
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Term
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Definition
| Cortex: molecular, purkinje, granular, and medulla |
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Term
| What does the medulla contain |
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Definition
| contains the deep cerebellum nuclei; where the purkinje fibers synapse |
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Term
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Definition
| Where the purkinje axons of the vermis synapse in the medulla |
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Term
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Definition
| where the purkinje axons from the Intermediate hemisphere synapse |
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Term
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Definition
| location in the medulla where the Lateral hemisphere purkinje axons synapse |
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Term
| Function of the basal ganglia |
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Definition
| major job is to start the movement; influences UMN in the ipsilateral cerebral cortex |
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Term
| Major Components of the basal ganglia |
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Definition
Striatum (Caudate nucleus: medial to the internal capsule, Putamen: lateral to the internal capsule)
The internal and external segments of the globus pallidus
the substantia nigra (midbrain)
internal capsule
Subthalamic nucleus |
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Term
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Definition
Contains GABA and cholinergic neurons which inhibt GABA neurons in the direct pathway and excite GABA neurons in the indirect pathway; D1 receptors; D2 receptors (DOPA neurons from substantia nigra; Cholinergic neurons (Ach) drives the indirect pathway, decreasing cortical excitation
• |
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Term
| sub parts of the striatum |
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Definition
Caudate nucleus: medial to the internal capsule
Putamen: lateral to the internal capsule |
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Term
| Neurons of the External and internal Segments of the globus pallidus : |
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Definition
Internal: GABA neurons, projects to motor nuclei of the thalamus
External: Components of the Indirect Basal Ganglia Pathway; projections to the Subthalamic nucleus |
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Term
| Contents/ Functions of the Internal Capsule: |
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Definition
| carrying all the axons that are going into or out of a cerebral hemisphere (motor-out, sensory-in); subdivides the basal ganglia |
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Term
| Neurons of the Substantia nigra (in midbrain): |
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Definition
| Contains DOPA neurons; project into the direct and indirect b.g. pathways, where they enhance or suppress the pathway. (disinhibition: result of a 2- DOPA neuron pathway) |
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Term
| Neurons of the Subthalamic nucleus (diencephalon): |
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Definition
| Contains Glutatmate neurons that project to the Internal Segment of the globus pallidus; part of the indirect pathway; Direct pathway: use D1 receptors; Indirect pathway: D2 receptors |
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Term
| Direct Basal Ganglia Pathway main function |
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Definition
| Excites motor cortex and promotes initiation of movement |
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Term
| Direct Basal Ganglia Pathway: from cortex to thalamus |
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Definition
1. Excitatory Glutanergic neurons from the cortex synapse on the GABA neurons in the striatum (beginning of pathway)
2. GABA neurons synapse on the second set of GABA neurons in the Internal 3. Segment of the globus pallidus (2 neurons pathways are used for disinhibition)
3. The GABA neurons then synapse on the VA/VL nuclei of the thalamus
4. The neurons form the thalamus are excitatory (Glutamate) and their axons travel to the motor cortex and influence Upper Motor Neurons
5. DOPA neurons from the substantia nigra project to the striatum and enhance the direct basal ganglia pathway |
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Term
| Indirect Basal Ganglia Pathway functions to... |
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Definition
| balances the direct pathway |
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Term
| Indirect Basal Ganglia Pathway: from cortex to thalamus |
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Definition
1. Excitatory Glutanergic neurons from the cortex synapse on the GABA neurons in the striatum (beginning of pathway)
2. Striatum axons then synapse on Glutamate neurons in the subthalamic nucleus (diencephalon); these excitatory neurons synapse on the Internal Segment of the globus pallidus;
3. The Internal Segment of the globus pallidus sends inhibitory GABA neurons to the VA/VL Thalamic nuclei
4. This reduces the activity in the motor cortex and suppresses the direct basal ganglia pathway
5. Excitatory Cholinergic neurons (Ach) found with in the striatum, enchance the Indirect Basal Ganglia pathway
6. DOPA neurons synapse on D2 receptors in the striatum, inhibit indirect pathway (cell bodies in the substantia nigra) |
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Term
A. Direct Pathway lesions:
3 Movement disorders : |
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Definition
1. Dyskinesias: diminished voluntary movement and presence of tics
2. Involuntary tremor at rest
3. Underactive motor cortex |
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Term
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Definition
| degenerative disease of the dompaminergic neurons in the substantia nigra |
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Term
| Symptoms of Parkinson's Disease |
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Definition
Problems iniating movements
2. Reduction in velocity and amplitude of movement
3. Pill rolling tremor at rest (fingers)
4. High motor Tone **** ???
5. Stooped posture, expressionless face, accelerating gait (chasing center of gravity) |
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Term
| Movement disorders of Indirect Pathway lesions (3) |
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Definition
o Overactive motor cortex
o Hyperkinetics disturbances
o Pronounced involuntary movements |
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Term
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Definition
| purposeless involuntary movements. Quick jerks that maybe superimposed on voluntary movemtns (indirect pathway lesion) |
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Term
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Definition
| Autosomal Dominant inheritance; degeneration of GABA neurons in the striatum (indirect pathway lesion) |
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Term
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Definition
| slow, writhing involuntary movements (most evident in fingers and hands); also seen in Huntington’s patients (indirect pathway lesion) |
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Term
| a. Subthalamic nucleus Lesions |
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Definition
| i. Hemiballismus: Violent projectile ballistic movements of a limb and observed in limb contralateral to the lesion in the subthalamic nucleus |
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Term
| What can cause Hemiballismus ? |
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Definition
| can be caused by stroke of a branch off the posterior cerebral artery in hypertensice patients |
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Term
| what is it Hemiballismus? |
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Definition
| ii. Violent projectile ballistic movements of a limb and observed in limb contralateral to the lesion in the subthalamic nucleus |
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Term
| What does the Cerebrocerebellum Pathway bring to the cerebellum and to what part does it bring it to |
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Definition
| Motor plan to the lateral hemisphere |
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Term
| What information does the Inferior Olivary Nucleus bring to the cerebellum and what fibers does it use? |
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Definition
| Climbing Fibers: “Error Detectors” of muscle performance; info from cortex, brainstem, and spinal cord; |
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Term
| Vestibular Fibers are involved in... |
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Definition
| involved in balance eye movements, most of the inputs are from central processes of the vestibula nerve and from vestibular nuclei |
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Term
| How do Mossy Fibers influence Purkinje cells? |
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Definition
1. Mossy fibers synapse with granule cells (only excitatory cell in the cerebellum, use gluatamate),
2. the granular cells ascend their axons up to the molecular layer and bifurcate to form parallel fibers; 3. these Parallel fibers then go to synapse on Purkinje fibers; |
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