Subcortical control of movement

Question 1

Where is the brainstem located and what 3 parts is it made of?

Answer 1

Brainstem sits at the top of the spinal cord, made of:
1) Medulla
2) Pons
3) Midbrain

Question 2

What does the medulla do?

Answer 2

Sits on lower half of brainstem (right on top of spinal cord), controls very basic motor functions:
 Cardiac – chemoreceptors sense O2 levels in brain and alter heart rate and blood pressure
 Respiration – chemoreceptors sense changes in blood and increase breathing rate
 Reflexes (coughing, sneezing, swallowing)

Question 3

What does the pons do?

Answer 3

Contains nuclei that relay signals from forebrain to cerebellum. Nuclei that deal primarily with sleep, respiration, swallowing, bladder control, hearing, equilibrium, taste, eye movement, facial expressions, facial sensation, and posture.

Question 4

What does the midbrain do?

Answer 4

 Tectum controls rapid orientation of the head and neck:
 Superior colliculus – vision
 Inferior colliculus – sound
 Substantia nigra – Parkinson’s disease
 Also associated sleep and wake cycles, alertness, and temperature regulation

Question 5

What are the 2 important brainstem nuclei groups?

Answer 5

• Reticular formation – a set of interconnected nuclei located throughout the brainstem
• Vestibular nuclei (VN) – nuclei for the vestibular system and are located in brainstem

Question 6

What is the relationship between the vestibulospinal tract and vestibular nuclei?

Answer 6

Vestibulospinal tract originates in vestibular nuclei and sends most of their output to the spinal cord and to muscles that move the eyes

Question 7

What is the relationship between the reticulospinal tract and reticular formation?

Answer 7

Reticulospinal tract originates in reticular formation (these tracts function in maintaining tone, posture and balance)

Question 8

What is the input/output ratio of the cerebellum

Answer 8

40:1 (input: output)

Question 9

Superior cerebellar peduncle

Answer 9

Efferent (out) pathway to the red nucleus and cortex (via thalamus) and sup colliculus

Question 10

Middle cerebellar peduncle

Answer 10

Most fibres originate in the pons
Input from sensory, visual, vestibular and motor systems
But its largest input is from cortex

Question 11

Inferior cerebellar peduncle

Answer 11

Carries information to and from the spinal cord (and the body) and vestibular nuclei

Question 12

What is the red nucleus and what does it do?

Answer 12

Red nucleus is a collection of cell bodies in the midbrain. It receives a large input from the cerebellum and primary motor cortex.

Red nucleus = origin point for rubrospinal fibres

Question 13

What course do rubrospinal fibres take once exiting the red nucleus?

Answer 13

Cross the midline, then course in the ventrolateral part of the brainstem to the cord, in which they occupy the same part of the white matter as the corticospinal tract.

Question 14

Where do rubrospinal fibres terminate?

Answer 14

In the cervical and lumbar enlargements of the cord. This contains motor neurones for the muscles in the fore and hindlimbs respectively.

Data indicates that the rubrospinal tract controls the shaping of the hand during reach-to-grasp movements

Question 15

What are the basal ganglia’s functions?

Answer 15

• Movement regulation
• Skill learning
• Habit formation
• Reward systems
• Selection of appropriate behaviours
• Self-initiation of behaviours

Question 16

What are the 2 pathways through the basal ganglia called?

Answer 16

Direct pathway and indirect pathway.

Question 17

What does the direct pathway of the BG do?

Answer 17

Runs directly through the BG. It has an excitatory effect of the cortex, and its net effect is pro-movement

Question 18

What does the indirect pathway of the BG do?

Answer 18

Long loop through BG. It has an inhibitory effect on the cortex, and its net effect is anti-movement.

Question 19

What is the difference between Basal Ganglia and Cerebellum

Answer 19

Damage to BG produces states where there is either too much OR too little movement. Damage to the Cerebellum produces states where movement can still be made, but the movement is uncoordinated.