Motor Control Flashcards
What is the role of the basal ganglia in the motor pathway?
To initiate and terminate movement. It suppresses any unwanted movements and establishes normal level of tone.
What is the role of the cerebellum in the motor pathway?
Controls UMN activity, connects to the MC via the thalamus and to the brainstem. Monitors movements for differences in intended and actual movements
What are the two types of UMN and where do they input?
Direct motor pathway - input to LMN
Indirect motor pathway - input to LMN from motor centres in the brainstem
What is the role of the UMNs?
Planning, initiating and directing movements
What is proprioception?
A sensory receptor that responds to position and movement - works out orientation of limbs
What are the different types of fibres present in a muscle?
Bag fibres and chain fibres, gamma-efferents and afferent fibres
What are the two types of afferent fibre?
Type I and II
What phase of the muscle stretch do type I fibres relay on to?
Dynamic phase
What phase of the muscle stretch do type II fibres relay on to?
Static phase
What type of terminal endings do BFs have?
‘Flower spray’ type terminal endings of afferent fibres embedded in the equatorial regions, dynamic and static gamma fibres
What type of terminal endings do CFs have?
Annulospiral endings (when these coils are pulled apart it initiates an AP, static and dynamic gamma efferents
What happens if the spindle is unloaded and loses tension?
No stretch information goes to the brain
What are gamma-motorneurons activated with?
Alpha-motorneurons
What can gamma-activity be changed?
Serotonin increases activity, noradrenaline decreases activity
What happens when you stimulate gamma-motorneurons with 5HT?
Intrafusal fibres become slightly stiffer
What happens in you inhibit gamma-motorneurons with noradrenaline?
The intrafusal fibres become more elastic
Describe the pathway from the central process of the DRG to the primary somatosensory cortex
- Central processes of the DRG synapse on neurons in the gracile and cuneate nuclei in the lower medulla
- Axons from these nuclei ascend in medial lemniscus and synapse on neurons in VPLN of the thalamus
- Neurons of the lateral nucleus send axons to the primary somatosensory cortex
Where are primary and secondary somatosensory cortices found?
In the anterior parietal lobe and the posterior parietal cortex
What does lesioning SI lead to?
Proprioceptive deficits
