Week 11 - The Cerebellum Flashcards
What is the primary function of the cerebellum?
To coordinate and predict movement by integrating sensory information and motor plans.
The cerebellum compares peripheral information regarding proprioception, muscle tone, and environmental cues with motor plans from the cortex.
What are the three major functions of the cerebellum?
- Grouping movements for selective responses
- Maintaining upright posture
- Regulating muscle tone
These functions are critical for motor control and balance.
Where is the cerebellum located?
In the posterior cranial fossa, separated from the cerebral cortex by the tentorium cerebelli.
It lies over the fourth ventricle and connects to the brainstem through three cerebellar peduncles.
What are the three lobes of the cerebellum?
- Anterior lobe
- Posterior lobe
- Flocculonodular lobe
The anterior and posterior lobes are separated by the primary fissure.
What is the vermis in the cerebellum?
The midline structure of the cerebellum that connects the right and left hemispheres.
The vermis is important for coordinating movements along the body’s midline.
What is the role of the cerebellar peduncles?
To connect the cerebellum to the brainstem and carry all information to and from the cerebellum.
The three cerebellar peduncles are the inferior, middle, and superior cerebellar peduncles.
What is the blood supply to the cerebellum?
- Anterior inferior cerebellar artery
- Posterior inferior cerebellar artery
- Superior cerebellar artery
These arteries arise from the vertebral basilar system.
True or False: The cerebellum has a direct pathway to lower motor neurons.
False
The cerebellum exerts control via the cerebral cortex and the brainstem.
What is the function of the vermal zone of the cerebellum?
Influences movements of the long axis of the body, such as neck and torso movements.
This zone plays a key role in maintaining posture and balance.
Fill in the blank: The cerebellum receives proprioceptive information from the _______.
[spinal cord]
Proprioceptive information helps the cerebellum monitor muscle status and position.
What are the two types of afferent fibers in the cerebellar cortex?
- Mossy fibers
- Climbing fibers
These fibers convey impulses to the cerebellar cortex and are identified by their histological appearance.
What are the three layers of the cerebellar cortex?
- Granular cell layer
- Purkinje cell layer
- Molecular layer
Each layer has distinct types of cells and functions.
What type of cells are predominant in the granular cell layer?
Granule cells
Granule cells are abundant and have multiple dendrites that receive mossy fiber inputs.
What is the role of Golgi cells in the cerebellar cortex?
Inhibitory GABA-ergic interneurons that modulate the activity of granule cells.
Golgi cells help regulate the excitability of the cerebellar cortex.
What is the function of the inferior cerebellar peduncle?
Connects the cerebellum to the medulla oblongata and carries vestibular and proprioceptive information.
It plays a crucial role in conveying sensory information to the cerebellum.
From where does the cerebrocerebellum receive input?
From the cerebral cortex via the ipsilateral pontine nuclei.
This area is involved in planning and coordination of voluntary movements.
What type of information does the vestibulocerebellum process?
Information related to balance and the position of the head in space.
This part of the cerebellum receives inputs primarily from the vestibular nuclei.
What is the primary route for the cerebral cortex to communicate with the cerebellum?
Through the deep pontine nuclei.
Axons from the cortex synapse here before projecting to the cerebellum.
What does the dentatrubrothalamic tract connect?
The dentate nucleus of the cerebellum to the red nucleus and then to the thalamus.
This pathway is important for relaying motor information.
What type of cells are Golgi cells?
Inhibitory GABA-ergic interneurons
Golgi cells are found in the granular layer and synapse with granule cells and mossy fibres.
What is the primary neurotransmitter used by Purkinje cells?
GABA
Purkinje cells are inhibitory and project to deep cerebellar nuclei.
What do mossy fibres originate from?
All cerebellar afferents except the inferior olivary nuclear complex
They include afferents from the spinal cord, posterior column nuclei, trigeminal system, pontine, and vestibular nuclei.
True or False: Climbing fibres form a one-to-one synapse with Purkinje cells.
True
Each climbing fibre forms an excitatory synapse with one Purkinje cell.
What are the two types of inhibition exerted by Golgi cells?
Feed-forward inhibition and feedback inhibition
Feed-forward involves mossy fibres exciting Golgi cells, while feedback involves granule cells exciting Golgi cells.
What is the net effect of Golgi cell activation in the cerebellar circuit?
Inhibition of granule cells
This limits granule cell discharge and influences Purkinje cell activity.
What type of cells are basket and stellate cells?
Inhibitory GABA-ergic cells
They synapse with Purkinje cells and receive input from parallel and climbing fibres.
How do parallel fibres affect Purkinje cells?
They activate Purkinje cells
Parallel fibres are axons of granule cells located in the molecular layer.
What is the role of climbing fibres in the cerebellar circuit?
Directly activate Purkinje cells
Climbing fibres do not involve interneurons.
What are the deep cerebellar nuclei?
Dentate nucleus, emboliform nucleus, globose nucleus, fastigial nucleus
They are arranged bilaterally and mediate different functions.
What is disinhibition in the context of cerebellar output?
Release of inhibition that increases deep cerebellar nuclei excitation
Occurs after Purkinje cell activation ceases.
What is the primary output of the cerebellar cortex?
Purkinje cells
These cells are inhibitory to the deep cerebellar nuclei.
Fill in the blank: The fastigial nuclei project to the _______ and _______.
vestibular nuclei; reticular formation
They project topographically and bilaterally.
What do the interposed nuclei project to?
Contralateral red nucleus
They are involved in controlling flexor motor neurons.
What is the feedback circuit involving the dentate nucleus?
Dentate nucleus → ventrolateral thalamus → motor cortex
This circuit assists in planning and coordination of motor responses.
What is the role of the vestibulocerebellum?
Control of eye and head position
It integrates vestibular inputs to modify actions accordingly.
True or False: All output from the cerebellar cortex is excitatory.
False
Output is through inhibitory Purkinje cells to deep cerebellar nuclei.
What type of control does the spinocerebellum have over muscles?
Control over extensor and axial muscles
It regulates muscle tone and standing posture.
