FE: Lecture 6: Cerebellum and Basal Ganglia Anatomy

Question 1

Which lobe of the cerebellum is the largest?

Answer 1

posterior

Question 2

What is function of inferior cerebellar peduncle?

Answer 2

input from medulla and spinal cord

output to medulla

Question 3

What is function of middle cerebellar peduncle?

Answer 3

input from pons

Question 4

What is function of superior cerebellar peduncle?

Answer 4

output to midbrain and thalamus- crosses in decussation of SCP

also ventral spinocerebellar input

Question 5

Where is the fastigal nucleus in comparison to other nucleus?

Answer 5

most medial

Question 6

Where is the interposed nuclei?

Answer 6

in the middle of the other two nuclei

Question 7

Where is the dendate nucleus?

Answer 7

most lateral and is the biggest in humans

Question 8

What is a positive Romberg sign?

Answer 8

has ataxia on the right side, veers to right during gait, cant stand on right leg alone, intentional tremor R UE

lesion in right cerebellum b/c this motor system does not cross or double crosses

Question 9

What cerebellar ataxia?

Answer 9

no paralysis but serious movement problems

Question 10

What is vestibulocerebellar ataxia?

Answer 10

similar to vestibular nerve damage- imbalance

leaning off midline, sway when walking, nystagmus and vertigo

damage to flocculonodular lobe

Question 11

What is spinocerebellar ataxia?

Answer 11

truncal ataxia- drunken sailor’s gait trunk and proximal limbs

damage to anterior lobe and vermis - from degeneration or alcohol

difficulty walking in a straight line

Question 12

What is cerebrocerebellar ataxia?

Answer 12

appendicular ataxia- distal limbs most affected

damage to posterior lobe

dysmetria- ability to use proprioception to control movements

dysdiadochokinesia- can’t do rapid automated movements

intentional tremor- cant control movement when you get closer to what you want to do

Question 13

What is the procedure of Romberg test?

Answer 13

narrow base of support and compare sway with eyes open and closed

positive if sway with eyes closed due to loss of unconscious proprioception

Question 14

What is an output neuron in the cerebellum?

Answer 14

Purkinjee

Question 15

What are the intrinsic neurons of the cerebellum?

Answer 15

granule cells- excitatory

basket, golgi, stellate cells- inhibitory

Question 16

What are the afferent fibers of the cerebellum?

Answer 16

extrinsic- mossy and climbing

intrinsic- parallel

Question 17

What are different internal circuits of cerebellum?

Answer 17

1. mossy fibers to granule cell- from spinal cord, pons and reticular nuceli (activate golgi cells as well)
2. Granule cells then go to purkinjee cells- also activates basket cells
3. Climbing fibers also go to purkinjee cells from inferior olive

Question 18

What is the function of purkinjee cells?

Answer 18

these integrate activity, by going to deep nuclei and inhibits them

cerebellum modulates movements does not elicit movement

Question 19

How does information from spinal cord get to cerebellum?

Answer 19

unconscious proprioception via spinocerebellar and cuneocerebellar tracts

Question 20

How does information get from vestibular nuclei to cerebellum?

Answer 20

head position and acceleration via the mossy fibers

Question 21

How does information from inferior olive get to cerebellum?

Answer 21

projects to cerebellum via inferior cerebellar peduncle

Question 22

How does information from cerebral cortex get to cerebellum?

Answer 22

contralaterally through pontine nucleus

Question 23

Describe the pathway of the ipsilateral dorsal spinocerebellar tract?

Answer 23

originates in Clarke’s nucleus (T1-L2) and goes up to spinocerebellum via the inferior cerebellar peduncle

damage to this tract produces trunk and lower limb ataxia ipsilateral Romberg sign

Question 24

Describe the pathway of the ipsilateral cuneocerebellar tract?

Answer 24

originates in the external cuneate nucleus (mostly in cervical levels) then up to spinocerebellum via inferior cerebellar peduncle

damage produces UE ataxia, no Romberg sign unless you stood on your hands

Question 25

Describe the pathway of the bilateral ventral spinocerebellar tract?

Answer 25

starts at lumbar region and synapse in dorsal horn

goes to spinocerebellum in two ways:

1. ipsilateral projection- via inferior cerebellar peduncle
2. crossed projection- ICP to CL cerebellum
   SCP to ipsi cerebellum (recrossed)

bilateral so no major clinical signs with ipsi damage

Question 26

What is the spinocerebellum?

Answer 26

vermis and paravermal cerebellar cortex

Question 27

What part of the cerebral cortex does the cerebellum control?

Answer 27

contralateral cerebellum

Question 28

What are the descending outputs from cerebellum?

Answer 28

1. floculonodular lobe to fastigal nuclei

2. anterior lobe to interposed nuclei

Question 29

From fastigal and interposed nuclei where do outputs go?

Answer 29

to brainstem UMN

1. Vestibular nuclei- via ICP, extensor tone control
2. reticular nuclei- via ICP, extensor tone control
3. Superior colliculus- via SCP head and eye movements

Question 30

What is ascending pathway from cerebellum?

Answer 30

1. posterior lobe of cerebellar cortex to interposed and dendate nucleus
2. then via SCP goes to CL motor thalamus (VA and VL)
3. motor thalamus to motor cortex