Motor Control

Question 1

What is the role of the basal ganglia in the motor pathway?

Answer 1

To initiate and terminate movement. It suppresses any unwanted movements and establishes normal level of tone.

Question 2

What is the role of the cerebellum in the motor pathway?

Answer 2

Controls UMN activity, connects to the MC via the thalamus and to the brainstem. Monitors movements for differences in intended and actual movements

Question 3

What are the two types of UMN and where do they input?

Answer 3

Direct motor pathway - input to LMN

Indirect motor pathway - input to LMN from motor centres in the brainstem

Question 4

What is the role of the UMNs?

Answer 4

Planning, initiating and directing movements

Question 5

What is proprioception?

Answer 5

A sensory receptor that responds to position and movement - works out orientation of limbs

Question 6

What are the different types of fibres present in a muscle?

Answer 6

Bag fibres and chain fibres, gamma-efferents and afferent fibres

Question 7

What are the two types of afferent fibre?

Answer 7

Type I and II

Question 8

What phase of the muscle stretch do type I fibres relay on to?

Answer 8

Dynamic phase

Question 9

What phase of the muscle stretch do type II fibres relay on to?

Answer 9

Static phase

Question 10

What type of terminal endings do BFs have?

Answer 10

‘Flower spray’ type terminal endings of afferent fibres embedded in the equatorial regions, dynamic and static gamma fibres

Question 11

What type of terminal endings do CFs have?

Answer 11

Annulospiral endings (when these coils are pulled apart it initiates an AP, static and dynamic gamma efferents

Question 12

What happens if the spindle is unloaded and loses tension?

Answer 12

No stretch information goes to the brain

Question 13

What are gamma-motorneurons activated with?

Answer 13

Alpha-motorneurons

Question 14

What can gamma-activity be changed?

Answer 14

Serotonin increases activity, noradrenaline decreases activity

Question 15

What happens when you stimulate gamma-motorneurons with 5HT?

Answer 15

Intrafusal fibres become slightly stiffer

Question 16

What happens in you inhibit gamma-motorneurons with noradrenaline?

Answer 16

The intrafusal fibres become more elastic

Question 17

Describe the pathway from the central process of the DRG to the primary somatosensory cortex

Answer 17

1. Central processes of the DRG synapse on neurons in the gracile and cuneate nuclei in the lower medulla
2. Axons from these nuclei ascend in medial lemniscus and synapse on neurons in VPLN of the thalamus
3. Neurons of the lateral nucleus send axons to the primary somatosensory cortex

Question 18

Where are primary and secondary somatosensory cortices found?

Answer 18

In the anterior parietal lobe and the posterior parietal cortex

Question 19

What does lesioning SI lead to?

Answer 19

Proprioceptive deficits