Lecture 8 Brainstem and motor disorders

Question 1

Ears

Answer 1

Cerebral peduncles

Question 2

Eyebrows

Answer 2

Substantia nigra that releases dopamine

Question 3

Eyes

Answer 3

Red nucleus

Question 4

Tears

Answer 4

Ascending sensory pathways

• medial lemniscus pathway - dorsal column
• spinothalamic tract

Question 5

Nose

Answer 5

Occulomotor nucleus
Edinger Westphal nucleus
Motor nucleus

• for accommodation reflex

Question 6

Mouth

Answer 6

Cerebral aqueduct connecting the third and fourth ventricle

Question 7

Around the mouth

Answer 7

Peri-aqueductal grey matter 
Function:
- pain perception 
- contains progesterone receptors that alter pain tolerance during menstruation
- urinary continence

Question 8

Double chin

Answer 8

Tectum of the midbrain contains colliculi for vision and hearing

Question 9

Lentiform nucleus

Answer 9

Putamen and globus pallidus

Question 10

Striatum

Answer 10

Putamen and caudate nucleus

Question 11

What shape in the caudate nucleus

Answer 11

C shaped due to the lateral ventricles which are also C shaped due to the temporal horn that goes into the temporal lobe

Question 12

Parts of the cerebellum

Answer 12

Cerebellar peduncles - connects the cerebellar to the brain stem

• superior - midbrain
• middle - pons
• inferior - medulla

Vermis - midline structure between the cerebellar hemispheres that control the trunk

Cerebellar tonsil - can compress the medulla during a rise in intracranial pressure

Question 13

Basal ganglia function

Answer 13

Decide the most appropriate set of movements from a motor plan provided by the prefrontal cortex

Act via:

• Direct pathway
• Indirect pathway

Question 14

Direct pathway

Answer 14

Causes excitation of the cerebral cortex to facilitate motor movements

Question 15

Indirect pathway

Answer 15

Inhibits the cerebral cortex to inhibit motor movements

Question 16

Role of dopamine

Answer 16

Acts as a kick starter

• acts on D1 receptors of the direct pathway which causes excitation of the direct pathway
• acts on D2 receptors of the indirect pathway which inhibits the indirect pathway

Question 17

Role of the cerebellum

Answer 17

Using proprioception input via the spinocerebellum tract, determines an appropriate sequence to conduct the motor plan

Question 18

Parkinson’s disease triad

Answer 18

Tremor - pill rolling tremor
Lead pipe rigidity - resistance to full range of movement
Bradykinesia

+/- psychiatric features such as depression
Micrographia - small handwriting
Hypophonia
Dementia (Lewy body)

Question 19

Bradykinesia

Answer 19

Slowness of movement
Mask like face
Trouble stopping and starting with destinations gait
Walk slow

Question 20

Cause of Parkinson’s disease

Answer 20

Degeneration of the substantia nigra therefore less dopamine release

Decreased inhibition of the indirect pathway therefore increased movements

Decrease stimulation of the direct pathway

Question 21

Causes of huntington’s disease (chorea)

Answer 21

Decreased activity of the indirect pathway therefore decreased inhibition of the globus pallidus external segment resulting in increased movements

Question 22

Chorea

Answer 22

Abnormal involuntary movement does order

Question 23

Features of Huntington’s disease

Answer 23

Autosomal dominant

• choreiform movements
• dystonia
• incoordination
• psychiatric features

Question 24

Dystonia

Answer 24

Uncontrollable muscle contraction causing twisting, abnormal posture or repetitive movements

Question 25

Hemiballismus

Answer 25

Destruction of subthalamic nucleus therefore less excitation of the globus pallidus internal segment Causes increased movement - ballistic movements on one side

Question 26

Ballistic movements

Answer 26

- no one side | - rotating

Question 27

Basal ganglia lesions

Answer 27

Affects the contralateral side

Question 28

Cerebellar lesions

Answer 28

Affects the ipsilateral side

Question 29

Symptoms of cerebellar lesions

Answer 29

``` Dysdiadochokinesis Ataxia Nystagmus Intention tremor Slurred speech (dysarthria) Hypotonia ```

Question 30

Lesion in the vermis

Answer 30

Affect the trunk e.g. trunk ataxia | When sitting down, one falls to one side

Question 31

Dysdiadochokinesis

Answer 31

Difficulty with rapidly alternating movements

Question 32

Nystagmus

Answer 32

Flickering movements of the eyes that are fast phase towards the side of the lesion

Question 33

How to test for intention tremor

Answer 33

Finger nose test | - past pointing - go beyond finger

Question 34

Cerebellar pathway

Answer 34

1. Proprioception receptors in the muscle spindle send afferent a to the ipsilateral cerebellar hemisphere viabthe dorsal spinocerebellar pathway 2. Motor innervation from the precentral gyrus has efferents that travel to the pontine nucleus via the corticospinal pathway 3. From the pontine nucleus where is synapses, it desuccates to the CONTRALATERAL cerebellar hemisphere 4. Collating the data, the cerebellum sends axons to the CONTROLATERAL primary motor cortex via the cerebellum-thalamo- cortical pathway but first synapses at the thalamus 5. Motor efferent are sent to the effector muscle via the corticospinal pathway after decussating