FE: Lecture 6: Cerebellum and Basal Ganglia Anatomy Flashcards
Which lobe of the cerebellum is the largest?
posterior
What is function of inferior cerebellar peduncle?
input from medulla and spinal cord
output to medulla
What is function of middle cerebellar peduncle?
input from pons
What is function of superior cerebellar peduncle?
output to midbrain and thalamus- crosses in decussation of SCP
also ventral spinocerebellar input
Where is the fastigal nucleus in comparison to other nucleus?
most medial
Where is the interposed nuclei?
in the middle of the other two nuclei
Where is the dendate nucleus?
most lateral and is the biggest in humans
What is a positive Romberg sign?
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
What cerebellar ataxia?
no paralysis but serious movement problems
What is vestibulocerebellar ataxia?
similar to vestibular nerve damage- imbalance
leaning off midline, sway when walking, nystagmus and vertigo
damage to flocculonodular lobe
What is spinocerebellar ataxia?
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
What is cerebrocerebellar ataxia?
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
What is the procedure of Romberg test?
narrow base of support and compare sway with eyes open and closed
positive if sway with eyes closed due to loss of unconscious proprioception
What is an output neuron in the cerebellum?
Purkinjee
What are the intrinsic neurons of the cerebellum?
granule cells- excitatory
basket, golgi, stellate cells- inhibitory
What are the afferent fibers of the cerebellum?
extrinsic- mossy and climbing
intrinsic- parallel
What are different internal circuits of cerebellum?
- mossy fibers to granule cell- from spinal cord, pons and reticular nuceli (activate golgi cells as well)
- Granule cells then go to purkinjee cells- also activates basket cells
- Climbing fibers also go to purkinjee cells from inferior olive
What is the function of purkinjee cells?
these integrate activity, by going to deep nuclei and inhibits them
cerebellum modulates movements does not elicit movement
How does information from spinal cord get to cerebellum?
unconscious proprioception via spinocerebellar and cuneocerebellar tracts
How does information get from vestibular nuclei to cerebellum?
head position and acceleration via the mossy fibers
How does information from inferior olive get to cerebellum?
projects to cerebellum via inferior cerebellar peduncle
How does information from cerebral cortex get to cerebellum?
contralaterally through pontine nucleus
Describe the pathway of the ipsilateral dorsal spinocerebellar tract?
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
Describe the pathway of the ipsilateral cuneocerebellar tract?
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
Describe the pathway of the bilateral ventral spinocerebellar tract?
starts at lumbar region and synapse in dorsal horn
goes to spinocerebellum in two ways:
- ipsilateral projection- via inferior cerebellar peduncle
- crossed projection- ICP to CL cerebellum
SCP to ipsi cerebellum (recrossed)
bilateral so no major clinical signs with ipsi damage
What is the spinocerebellum?
vermis and paravermal cerebellar cortex
What part of the cerebral cortex does the cerebellum control?
contralateral cerebellum
What are the descending outputs from cerebellum?
- floculonodular lobe to fastigal nuclei
2. anterior lobe to interposed nuclei
From fastigal and interposed nuclei where do outputs go?
to brainstem UMN
- Vestibular nuclei- via ICP, extensor tone control
- reticular nuclei- via ICP, extensor tone control
- Superior colliculus- via SCP head and eye movements
What is ascending pathway from cerebellum?
- posterior lobe of cerebellar cortex to interposed and dendate nucleus
- then via SCP goes to CL motor thalamus (VA and VL)
- motor thalamus to motor cortex
