Reflexes And Posture Flashcards
What is the hierarchy of the motor system?
Consists of 4 levels
Level 1: Spinal Cord
Level 2: Brainstem
Level 3: Motor cortex (including supplemental motor cortex and pre-motor cortex)
Level 4: Association areas
What is the role of specific sectors of the motor system?
Level 3 and Level 4 are important for planning and co-ordinating movements. Level 1 and 2 receive signal to control invididual muscles for posture changes.
What are the inputs to the motor system?
Basal ganglia and cerebellum which makes connections to the motor system via the thalamus.
What is the basal ganglia?
Subcortical nuclei which are important for the fine-tuning of motor control by sending signals via the thalamus to the motor cortex.
Consists of the caudate nuclei, subthalamic nuclei, substantia nigra, putamen, globus pallidus internal and external.
What is the lentiform nuclei?
Putamen and globus pallidus internal and external of the basal ganglia.
What is the corpus striatum?
Portion of the basal ganglia containing the lentiform nuclei and the caudate nuclei.
What is the pyramidal system?
Descending system which carries signals away from the CORTEX to the Brainstem or spinal cord. Consists of the corticobulbar and corticospinal tracts. Therefore, it controls voluntary movement.
What is the extra-pyramidal system?
Descending system which carries signals away from the BRAINSTEM to spinal cord. Therefore, it controls involuntary movement such as posture.
What is a reflex?
Instantaneous annd involuntary action in response to a stimuli, by bypassing the CNS.
How does a reflex action occur?
Receptor detects stimuli and transmits information down the sensory nerve which enters the dorsal root ganglion of the spinal cord grey matter and synapses with inter neuron. This relays it to the efferent nerve that leaves via the ventral horn to act on muscle to produce contraction.
Where does information enter the spinal cord?
Dorsal horn of grey matter.
Where does information leave the spinal cord?
Ventral horn of grey matter.
What is the role of the white matter in the spinal cord?
Composed of axon bundles to transmit information up and down the spinal cord.
What is the role of the grey matter in the spinal cord?
Releases information through axons for movement, memory.
What is the muscle spindle?
Stretch receptors parallel to muscle fibres which detects changes in muscle length. Consists of intrafusal and extrafusal muscle fibres and Ia afferents.
