Lecture 5 Cerebellum

Question 1

What does Cerebellum mean?

Answer 1

• Little Brain

Question 2

Why is the cerebellum called the “Silent Area”?

Answer 2

• Electrical stimulation does not produce any conscious sensation or motor movement
• Active when upright and conscious

Question 3

How many neurons does the cerebellum hold?

Answer 3

More than half the neurons in the brain

Question 4

How does the Cerebellum operate and what is it involved in?

Answer 4

• Adjusts movements in real time
• Involved in planning skilled movements
• Plays a role in motor learning

Question 5

What are the Cerebellar Peduncles

Answer 5

• Fibers connecting the cerebellum to the brain and spinal cord
• Input and output pathways
• Consists of Superior, middle and inferior fibers

Question 6

What do the deep nuclei of the cerebellum consist of?

Answer 6

• Contain the output neurons of the cerebellum

Question 7

What is the purpose of the Superior Cerebellar Peduncle?

Answer 7

• Mainly Efferent (output)

Question 8

What is the purpose of the Middle cerebellar peduncle?

Answer 8

• Mainly Afferent (input)

Question 9

What is the purpose of the Inferior Cerebellar Peduncle

Answer 9

• Mainly Afferent (Input)

Question 10

Of the Deep Nuclei of the Cerebellum, what are the nuclei starting from lateral to medial?

Answer 10

• Dentate Nucleus
• Emoliform Nucleus
• Globose Nuclei
• Fastigial Nucleus
  (Don’t Eat Greasy Food)

Question 11

What happens in Cerebellar Ataxia (cerebellar disease)?

Answer 11

• Affects the spatial accuracy and timing of voluntary movements

Question 12

What happens when bilateral cerebellar damage occurs?

Answer 12

• Jerky and irregular motor movements
• Difficulty with rhythmic movements
• Unstable stance and walking
• slurred speech
• disorders of eye movement
• Tremor during voluntary movement (NOT WHILE RESTING)

Question 13

IF abused, what substances can caused cerebellar degeneration?

Answer 13

• Ethanol
• Dilantin (epilepsy drug)
• Chemotherapeutic Agents

Question 14

How does the Cerebellum influence motor systems?

Answer 14

• Evaluates disparities between Intention (Motor Output) and Action (Sensory Feedback)

Question 15

With disparities between motor output and sensory feedback, how does the cerebellum adjust the body?

Answer 15

• It alters the output of the brainstem motor nuclei and motor cortex during movement

Question 16

What happens when the cerebellum is lesioned?

Answer 16

• Lesion causes motor incoordination (Ataxia)
• Affects IPSILATERAL SIDE of the body
• Paralysis DOES NOT occur

Question 17

In Clinic, which cerebellar lesions are possible to discern?

Answer 17

• Lesions of the midline structures
  OR
• Lesions of the Lateral Hemispheres

Question 18

What three systems can the cerebellum be divided into?

Answer 18

1. Vestibulocerebellum (Oldest)
2. Spinocerebellum
3. Cerebrocerebellum (newest)

Question 19

What portions of the cerebellum make up the vestibulocerebellum?

Answer 19

• Flocculonodular Lobe and parts of Vermis
• Phylogenetically oldest part

Question 20

What does the Vestibulocerebellum control?

Answer 20

• Controls balance, posture, and head-eye movements

Question 21

Where does the vestibulocerebellum receive input from?

Answer 21

• Input from the organ of balance located in the Inner ear
• (Vestibular Aparatus)

Question 22

What is the output from the vestibulocerebellum?

Answer 22

• output to the vestibulospinal and Reticulospinal tracts

Question 23

What portions of the cerebellum make up the spinocerebellum?

Answer 23

• Consist of the Vermis and Paravermis

Question 24

What is the spinocerebellum responsible for?

Answer 24

• concerned with muscle tone
• Movements of larger proximal limb muscles
• Important for locomotion

Question 25

Where does the Spinocerebellum receive input from?

Answer 25

- Unconscious Proprioceptive Input from the spinocerebellar pathways

Question 26

What is the output from the spinocerebellum?

Answer 26

- Rubrospinal tract

Question 27

What areas of the cerebellum are affected by a midline cerebellar lesion?

Answer 27

- Vestibulocerebellum - Spinocerebellum

Question 28

What are they signs of midline cerebellar lesion?

Answer 28

- Ipsilateral motor incoordination (Ataxia) - Vertigo: sensation of spinning or swaying - Truncal Ataxia: Loss of postural control (Impossible to stand/sit w/o falling over) - Wide Ataxic Gait: (wide stance) - Nystagmus: oscillating back and forth motions of eyes - (FINE coordination of limbs intact)

Question 29

What portions of the cerebellum are in the cerebrocerebellum?

Answer 29

- Lateral aspects of the Cerebellar hemispheres

Question 30

What is the Cerebrocerebellum responsible for?

Answer 30

- Skilled asymmetrical movement of the limbs (mainly upper) and speech - Planning skilled movements - Cognitive Functions

Question 31

What type of input does the Cerebrocerebellum receive?

Answer 31

- Mainly Sensory and Motor input from cerebral cortex - used to plan movements

Question 32

What is the output of the cerebrocerebellum?

Answer 32

- Output modulates the Lateral Corticospinal Pathway

Question 33

What happens when the Cerebrocerebellum is lesioned?

Answer 33

- Ipsilateral Cerebellar Ataxia - Difficulty with fine coordination of limb movements - Minor Gait disturbance - Dysarthria: Uncoordinated Speech (Muscle Strength and Sensation are NORMAL)

Question 34

What are some tests to identify cerebrocerebellum lesions?

Answer 34

- Finger to Nose - Heel to Knee

Question 35

Where does the Vestibulocerebellum output arise from?

Answer 35

- Fastigial Nucleus

Question 36

Where does the Spinocerebellum output arise from?

Answer 36

- Fastigial Nucleus - Globose Nucleus - Emboliform Nucleus

Question 37

Where does the Cerebrocerebellum output arise from?

Answer 37

- Dentate Nucleus