Basal Ganglia & Cerebellum

Question 1

Diagram showing basal ganglia

Answer 1

Question 2

The vestibular and reticular nuclei form tracts, what are they called? And function?

Answer 2

Vestibulospinal

and reticulospinal

• muscle tone & posture

Question 3

What are the two groups of basal ganglia pathways?

Answer 3

direct - initiates/facilitates movement

indirect - stops/inhibits movement

Question 4

Globus pallidus consists of two….

Answer 4

segments - medial and lateral

Question 5

Why are the caudate nucleus and putamen important?

Answer 5

They receive afferent fibres from the cerebral cortex, the thalamus, and the pars compacta of the substantia nigra

Question 6

Disorders of movement and the basal ganglia - General features (a list)

Answer 6

No paralysis,sensory loss or ataxia

Abnormal motor control,alterations in muscle tone

Abnormal involuntary movements

Slowness - bradykinesia

Loss or absence - hypokinesia, akinesia

Problems of stopping and starting

Abnormal postures, arm swinging in walking can be absent

Rigidity to passive movement is constant as opposed to spasticity

Cog-wheel v continuous

Tremor at rest

Chorea - fragmented purposeful components of a real movement

Dystonia - sustained contractions producing abnormal postures

Athetosis - slow sinuous writhing movements of axis

Myoclonus - short sharp movements

Tics

Question 7

Diagram of molecular layers of cerebellum

Answer 7

Question 8

Diagram of connections to the cerebellum

Answer 8

Question 9

Simple overview of cerebellar function

Answer 9

Motor cortex sends command to lower motor neurons in spinal cord

Simultaneously the command is recorded in cerebellum

Cerebellum receives information via spino-cerebellar tracts

This is information of what has actually happened

Cerebellum compares “intention” & “achieved”- computes difference

Purkinje cells send output from cerebellum to deep nuclei - dentate

Deep nuclei relay to thalamus to pre-motor cortex

Pre-motor cortex corrects motor cortex with difference

Error is corrected

Question 10

Basal ganglia lesions - signs

Answer 10

Contralateral signs

No paralysis or sensory loss

Abnormal control of posture & movement Parkinsons - tremor at rest

Slowness starting,carrying out movement - hypo/brady/akinesia

Abnormal involuntary movements

Rigidity to passive movement

Question 11

Cerebellar lesions (5 signs)

Answer 11

Ipsilateral signs

Nystagmus

Intention tremor

Dysarthria

Ataxia