L6. Cerebellum Flashcards
What are the 5 main functions of the cerebellum?
- posture and muscle tone
- coordination of fine and gross movements + eye movements
- balance and equilibrium
- motor planning and learning
- differentiation of actual versus intended movement
What are the 3 lobes of the cerebellum?
anterior lobe, posterior lobe, and flocculonodular lobe
Propulsive stereotyped movements are made possible by which lobe of the cerebellum?
anterior lobe
The coordination of movement is a function of which lobe of the cerebellum?
posterior lobe
Which lobe of the cerebellum is responsible for maintaining equilibrium and is connected to the vestibular system?
flocculonodular lobe
Which nuclei is associated with the anterior lobe?
interposed nuclei
Which nuclei is associated with the posterior lobe?
dentate nuclei
The fastigial nuclei is associated with which lobe of the cerebellum?
flocculonodular
According to the homunculus of the cerebellum, what are the three main sections? (hint: zones)
vermal, intermediate, and lateral zone
Which lobe is the largest division and is responsible for:
- planning and modulating movements
- motor learning
- controls movements of distal extremities
- includes speech
posterior lobe
Aside from regulating posture/muscle tone and movement of the proximal extremities, what else is the anterior lobe responsible for?
propulsive movements, adjustment of movement without stopping or initiating a new movement, comparator between intended and actual movements
Timing, coactivation of muscles, timing of sequential movements, and adjusting the Force, Rate, Direction, and ROM is a function of which lobe in the cerebellum?
posterior lobe
What are the functions of the flocculonodular lobe?
- controls balance and posture
- controls anti-gravity musculature
- ocular control and eye-hand coordination
Which zone is responsible for motor coordination and muscle tone of the neck, shoulder, thorax, abdomen, and hips?
vermal zone
A lesion at the vermal zone causes what?
truncal ataxia (drunken sailor gait)
What is the intermediate zone responsible for?
motor coordination and muscle tone of the distal limb (esp. hands and feet)
What is the lateral zone responsible for?
- motor control and muscle tone on the ipsilateral side of the body
- planning of sequential movement, involved in the conscious assessment of movement errors
What are the 3 main arteries that supply the cerebellum?
- superior cerebellar artery (SCA)
- anterior inferior cerebellar artery (AICA)
- posterior inferior cerebellar artery (PICA)
What occurs if there is a lesion at the lateral zone?
limb ataxia
What are the 3 cortical layers of the cerebellum?
molecular layer, Purkinje layer, granular layer
What is the outermost cortical layer of the cerebellum?
molecular layer
What cells are found at the molecular layer?
- basket cells (inner)
- stellate cells (outer)
- dendrites of the Purkinje and Golgi cells
- axons of the granule cells
What cell is found in the Purkinje layer?
cell bodies of the Purkinje cells
Is the connection from Golgi cells → Granule cells excitatory or inhibitory?
inhibitory
Out of the cells found in the cerebellum, which cell type is excitatory?
granule cells
Is the connection from Olive → Purkinje cells excitatory or inhibitory?
excitatory
What represents the efferent pathways from the cerebellum and receives direct excitatory inputs?
cerebellar nuclei
What are the 2 kinds of afferent cerebellar fiber systems?
climbing and mossy fibers
What are the 4 types of cerebellar nuclei found in the cerebellum?
fastigial nucleus (most medial), globose, emboliform, dentate (most lateral)
hint: Fat Guys Eat Donuts
What inhibits the cerebellar nuclei?
Purkinje cells
What neurotransmitter/s do mossy fibers use?
glutamate
What neurotransmitter/s do climbing fibers use?
glutamate or aspartate
Mossy fibers synapse with what cells?
granule cells
Climbing fibers synapse with what cells?
Purkinje cells
What is the main function of mossy fibers? (hint: gives more ‘diffused’ input)
FMS and feedback on ongoing movement
What are the three kinds of efferent cerebellar fiber system?
Vestibulocerebellum, Spinocerebellum, Neocerebellum
Climbing fibersare more precise in getting input, why?
it originates from the inferior olivary nucleus only. Mossy fibers originate from many structures.
What is the main function of climbing fibers? (hint: directly excites Purkinje cells)
motor learning
What is the main function of the vestibulocerebellum?
balance and gait
What is the main function of the spinocerebellum?
comparator functions
What are the three peduncles found in the cerebellum?
superior cerebellar peduncle, middle cerebellar peduncle, inferior cerebellar peduncle
What is the main function of the neocerebellum?
motor planning and coordination
What peduncle is also known as the “Brachium Conjuntivum” and contains afferent and ventral spinocerebellar functions and some fastigiobulbar tracts?
Superior Cerebellar Peduncle
Which part of the brain stem is the superior cerebellar peduncle attached to?
midbrain
Which peduncle is also known as “Brachium Pontis” and consists almost entirely of crossed afferent fibers from the contralateral pontine nuclei?
Middle Cerebellar Peduncle
Which part of the brain stem is the Middle Cerebellar Peduncle attached to?
Pons
What peduncle is also known as the “restiform body” and is attached to the medulla?
Inferior Cerebellar Peduncle
What is the efferent tract in the inferior cerebellar peduncle?
fastigiobulbar tract
Briefly explain the cerebellar circuitry.
- all afferent inputs go through the cerebellar nuclei and cortex.
- After processing, Purkinje neurons send INHIBITORY signals (GABAergic) to deep cerebellar nuclei.
- Output of deep cerebellar neurons are excitatory (via glutamate), influencing brainstem and cerebellar cortex via thalamus
What are the basic characteristic of cerebellar dysfunction?
errors in planning and execution on the ipsilateral side. Not really paralysis.
A vermal lesion would usually result in problems with which region/s in the body?
Truncal LE symptoms
A lesion at the lateral hemisphere of the cerebellum usually affects which region/s in the body?
UE symptoms
In which area of the cerebellum causes the most severe symptoms?
superior cerebellar peduncle and deep nuclei lesions
Symptoms produced by cerebellar lesions are more or less permanent. True or False?
False. It could improve over time.
Gait and speech disturbances could occur in cerebellar lesions. True or False?
True
What are the general dysfunctions associated with the cerebellum?
Dysdiadochokinesia , Ataxia, Nystagmus, Intention tremor, Scanning Speech (dysarthric), Hypotonia
(Hint: D-A-N-I-S-H)
What are the common causes of cerebellar dysfunction?
Tumor (Astrocytoma), Hypertensive Hemorrhage, Cerebellar infarctions, Metabolic disorders, Degenerative diseases
Disorders of stance and gait, particularly having a wide BOS and inability to do tandem walk, is characteristic of a dysfunction in what zone of the cerebellum?
Midline Zone Dysfunction
Aside from problems with stance/gait, what are the other symptoms of a midline zone dysfunction?
titubation, rotated & tilted head posture, oculomotor disorder, and no asynergia
What test can be utilized to evaluate a midline zone dysfunction?
Romberg Test or Romberg Tandem Test
The decomposition of movement (i.e. something to do with fluidity of movements) is associated with what kind of cerebellar dysfunction?
lateral zone dysfunction
What are the common symptoms of lateral zone dysfunction?
hypotonia, intention tremor, dysarthria, dysdiadochokinesia, dysmetria
(hint: H-I-D-D-D)
What evaluations can be done to diagnose lateral zone dysfunctions?
finger to nose test, finger to finger test, rapid finger tap, alternating pronate-supinate
