Motor System Disorders

Question 1

Where is the cerebellum located?

Answer 1

Posterior cranial fossa

Question 2

What is the role of the cerebellum?

Answer 2

Motor control and coordination

Question 3

How does the cerebellum communicate with the brainstem and cortex?

Answer 3

Superior = cerebellar peduncle attaches cerebellum to midbrain

Middle = cerebellar peduncle attaches cerebellum to pons

Inferior = cerebellar peduncle attaches cerebellum to medulla

Cerebellum communicates with the cortex via the thalamus

Question 4

Outline the tracks of the cerebellum

Answer 4

Lateral cerebellar hemispheres regulate distal structures – limbs

Tracts are ipsilateral = ipsilateral symptoms

Question 5

Explain how a lesion in the cerebellum can result in hydrocephalus

Answer 5

Extension of midline lesions can cause compression of the 4th ventricle

Question 6

What is the function of the vermis?

Answer 6

Regulating trunk musculature

Question 7

What do lesions in the vermis result in?

Answer 7

Truncal ataxia and abnormal gait

Question 8

What occurs to the cerebellar tonsil when ICP raises?

Answer 8

If ICP increases the tonsil can herniate though foramen magnum = compression of medulla

Question 9

Describe the symptoms of a cerebellar disease - DANISH

Answer 9

D = dysdiadochokinesis – impaired ability to perform rapid movements

A = ataxia – lack of voluntary coordination of muscle movements including gait

N = nystagmus – rapid eye movements when awake

I = intention tremor – finger nose point with tremor

S = slurred speech

H = hypotonia

Question 10

What structures make up the basal ganglia?

Answer 10

Lentiform nucleus = putamen, globus pallidus external and internal

Caudate nucleus

Thalamus

Substantia nigra (2 parts: pars compacta, pars reticulata)

Subthalamic nucleus

Question 11

What is the striatum?

Answer 11

Putamen + caudate nucleus

Question 12

What are the layers of the lentiform nucleus?

Answer 12

Putamen (lateral)

Globus pallidus external

Globas pallidus internal (medial)

Question 13

What is the role of the basal ganglia?

Answer 13

Stimulate the motor cortex

Question 14

In the absence of dopamine what does the direct pathway result in?

Answer 14

Stim the thalamus

Question 15

In the absence of dopamine what does the indirect pathway result in?

Answer 15

Inhib the thalamus

Question 16

What is the overall effect of dopamine in the direct and indirect pathway?

Answer 16

Motor cortex stimulation via the thalamus

Question 17

Where are the dopaminergic neurones found that deteriorate in parkinsons?

Answer 17

Substantia nigra – pars compacta

Question 18

How can dopamine cause both an excitatory and inhibitory effect on the putamen?

Answer 18

Diff sub types of receptors lead to either excitatory or inhibitory results

Question 19

What are the symptoms of basal ganglia disorder?

Answer 19

Abnormal motor control

Altered posture

Affects muscle tone

Dyskinesia

Question 20

Describe Parkinson’s

Answer 20

Degeneration of substantia nigra causes deficiency of dopamine

Chronic, progressive movement disorder

Triad of bradykinesia, tremor and rigidity

Question 21

What are the cardinal features of parkinsons?

Answer 21

Tremor-Resting – on movement the tremor disappears

Bradykinesia – slow movement

Hypertonia- Rigidity

Question 22

What are the associated features of Parkinson’s?

Answer 22

Hypophonia

Reduced facial expression

Micrographia

Dementia

Depression

Question 23

What is Huntington’s disease?

Answer 23

Autosomal-dominant, progressive neurodegenerative disorder

Loss of GABA neurones within the Striatum =

Loss of the indirect pathway = over-stimulation of the motor cortex = chorea

Question 24

What are the symptoms of Huntington’s disease?

Answer 24

Chorea

Dystonia

Incoordination

Cognitive decline

Behavioural difficulties

Question 25

What is Hemiballismus?

Answer 25

Dysfunction contralateral subthalamic nuclei damage = over-stim of motor cortex

Results in unilateral abnormal movement

Often secondary to sub-cortical stroke