Topic 11 Cerebellum anatomy physiology and impairments

Question 1

What is the role of the cerebellum?

what side of the body does it affect

Answer 1

Modulates & coordinates skillled volintary movements and speech
by comparing actual motor output to intended motor output and then ajusting the movement as nescessary

Maintain posture & balance

Maintains muscle tone

Coordination of volinary movement

Has an IPSILATERAL influence on body

Question 2

Name the 3 functional zones of the cerebellum

Answer 2

Lateral hemisphere(Cerebrocerebellum)
projects to DENTATE

Intermediate hemisphere (Spinocerebellum)
projects >INTERPOSED NUCLEUS(globose & emboliform)

Vermis & flocculonodular lobe (Vestibulocerebellum)
Projects to FASTIGIAL NUCLEUS

Question 3

What are the 4 nuclei of the cerebellum?

Answer 3

Dentate- Interposed nucleus
Globose -
Emboliform
Fastigial

Question 4

Describe the structure of the cerebellar cortex

Answer 4

Made of grey matter.
There are 3 layers:
Molecular cell layer(satelite cells & basket cells)
Purkinjie cell layer (principle cells of cerebellar cortex)
Granular cell layer( Granule cells & golgi cells)

ALL output from cerebellar cortex is carred by purkinje cells to central nuclei of cerebellum

Question 5

List the descending tracts in the spinal cord.

Which ones are medial and which are lateral?

Answer 5

Descending tracts

MEDIAL
Ventral corticospinal*
Reticulospinal
Vestibulospinal
Tectospinal

LATERAL
Lateral corticospinal *
Rubrospinal

Question 6

List the 3 cerebellar peduncles and the tracts they carry

Answer 6

Inferiorcerebellar peduncle(restiform body) near medulla

-Dorsal spinal cerebellar tract
from ipsilateral side of the body to cerebellum.

-Cuneocerebellar tract
from ipsilateral side of the body to cerebellum

-Olivocerebellar tract
from contralateral inferior olivary nucleus of medulla

-Vestibulocerebellar tract
From ipsilat vestibular ganglion & vestibular nucleu

• These are all afferent imputs(sensory)

MIDDLE CEREBELLAR PEDUNCLE

-Pontocerebellar tract
from contralateral pontine nuclei

SUPERIOR CEREBELLAR PEDUNCLE

fibres travelling from deep cerebellar nuclei to
contralateral red nucleus(midbrain) or thalamus(VA/VL)

Question 7

Describe the pathway of info into and out of cerebellum

Answer 7

1. Info enters cerebellum via ICP & MCP

CCT
DSCT
OCT
VCT

PCT

2. reaches cerebellar cortex
3. within cortex info must synapse with purkinje cell prior to leaving
4. Purkinje cells to dentate,globose,emboliform& fastigial
5. Most info leaves cerebellum via SCP *some vestibular leaves via ICP
6. From SCP info passes to the CONTRALATERAL rednucleus of midbrain or thalamus

7.To cerebral cortex
8. Through internal capsule
9.Descends through ventral brainstem via
Corticicospinal tract.
10. Information crosses at the pyramidal decussation

Question 8

Explain the pathology of friedreich’s ataxia
Include the neural structures involved

It is a disorder of movement

Answer 8

Autosomal recessive degenerative disorder of cerebellum and Posterior and Lateral collumns of the spinal cord.

Frataxin gene mutation results in mitochondrial ENERGY DEFECT. affecting:
Cerebellar vermis
Purkinje cells
Dorsal root ganglion(sensory)
Sensory nerves  @ nodes of ranvier

Spinal cord changes——
Cerebellum is deprived of SENSORY imput nescessary to coordinate movement.

• loss of sensory dorsal root ganglion CELLS
• degeneration of sensory axons in peripheral nerves, dorsal roots & posterior collumns

-Degeneration of spinocerebellar

Question 9

Which areas are damages by Freidreich’s Ataxia

Answer 9

DEGENERATION OF:

Dorsal root ganglion cells and axons
Peripheral sensory nerves @ nodes of ranvier
Sensory tracts in SC (Posterior collumns)
eg spinocerebellar tract

+slight degeneration of corticospinal tract (motor weakness

Cerebellar cortex is normal
Loss of neurons in DENTATE NUCLEUS(main source of cerebellar output)
Degeneration of superior cerebellar peduncles

Question 10

Freidreichs ataxia

Signs and symptoms
Management

Answer 10

Cerebellar ataxia
Dysarthria(ataxia of muscles of articulation)
Sensory Ataxia(Nothingcoming back dorsal columns)
Muscle weakness(Damage to tract)
Peripheral neuropathy
Scoliosis(
Cardiomyopathy(cells of heart need lots of energy, hypertrophy)
Diabetes

No active treatment only mx conditions

Question 11

Describe pathology of Arnold Chiari Malformation

Answer 11

Abnormalities in area where brain & SC meet
Causes part of cerebellum(tonsils) to protrude through foramen magnum into spinal canal.

Interferes with flow of CSF & causes hydrocephalus

Symptoms: Headache, vomiting, visual disturbances,diplopia, mental dullness, lack of coordination,paralysis of extremities, cerebellar ataxia, sensory disorders.

Question 12

Cerebellar atrophy

Answer 12

Cause: Chronic alcoholism

Atrophy of Rostral vermis due to loss of purkinje and granule cells. Take in most of calories from alcohol so develop deficiency in B1 Thiamine as they dont each much.

Thiamine dependent enzymes are concentrated in anterior vermis, so selective deficiency of thyamine dependent has an effect here

S&S broad bases stance
trunkal ataxia > staggering gait
little or no limb ataxia