Motor Control

Question 1

Outline reflex movements

Answer 1

Rapid reproducible autonomic motor responses to external stimulus
Employs simple neural circuit involving peripheral nerves and spinal cord
Does not require involvement of higher brain centres

Question 2

Outline voluntary movements

Answer 2

Wide variety of movements of varying speed, duration, and complexity
Typically involves complex patterns of sensory and motor processing
Initiated on demand in brain and mainly higher centres involved

Question 3

Outline the 5 steps involved in a stretch reflex

Answer 3

Stimulation of a receptor
Activation of a sensory neuron
Information processing in the CNS
Activation of a motor neuron
Response of a peripheral effector

Question 4

Outline mechanical ion channel gating

Answer 4

Muscle stretch receptors (proprioceptors) have mechanically gated ion channels. When stretched, channel opens, allows entry of positive charge, local depolarisation ensues, called receptor potential. If big enough, action potential will be triggered in sensory nerve and information will flow from site of stimulation

Question 5

Outline the 5 steps of a withdrawal reflex

Answer 5

Simulation of a receptor
Activation of a sensory neuron
Information processing in CNS
Activation of a motor neuron
Response of a peripheral effector

Question 6

Outline the pathway of voluntary movement

Answer 6

Sensory receptors stimulated
Sensory afferent devision PNS carries information
Information processing in CNS
Motor efferent devision of PNS - Somatic nervous system
Skeletal muscle effector

Question 7

Outline the hierarchy of motor complexity, low to height

Answer 7

Brain stem and spinal cord
Pons and medulla oblongata
Hypothalamus
Thalamus and midbrain
Basal nuclei
Cerebellum
Cerebral cortex

Question 8

What are the roles of the brain stem and spinal cord

Answer 8

Control simple cranial and spinal reflexes

Question 9

What are the roles of the pons and oblongata

Answer 9

Control balance reflexes an more complex respiratory reflexes

Question 10

what are the roles of the hypothalamus

Answer 10

Control reflex motor patterns related to eating, drinking, and sexual activity. Modifies respiratory reflexes

Question 11

What are the roles of the thalamus and midbrain

Answer 11

Control reflexes in response to visual stimuli and auditory stimuli

Question 12

What are the roles of the basal nuclei

Answer 12

Modify voluntary and reflexive motor patterns at the subconscious level

Question 13

What are thee roles of the cerebellum

Answer 13

Coordinates complex motor patterns through feedback loops

Question 14

What are the main functions of he cerebral cortex

Answer 14

Plans and initiates voluntary motor activity

Question 15

What is the prefrontal cortex

Answer 15

Organises thoughts and actions
Intimately involved in “executive functions”

Question 16

What functions is the prefrontal cortex involved in

Answer 16

Congestive function - acquiring knowledge through thought and experience
Social behaviour - planning, language, decision making, risk assessment, personality, emotion
Used to recall and consider information - not currently available from environment
Recall of past events - can be used to help plan future events

Question 17

What is the primary cortex

Answer 17

Upper motor neurons that initiate complex voluntary movements

Question 18

Summarise voluntary movements

Answer 18

Sensory info about environment ant state of body is used to plan movements. Neural commands sent to muscles to generate forces to execute movement
Desire to initiate a movement typically arises in association and pre frontal cortex
Various directly motor related regions of cortex are activated
Descending pathways (to brain stem and spinal cord) are activated
Spinal cord motor neurons activate skeletal muscles
Sensory information fed back into system, and the activity of motor neurons is modulated to modify and control the movement

Question 19

Outline the planning of a movement

Answer 19

Decision in frontal lobes
Prefrontal cortex prepares and executes movements of limbs
Basal nuclei allows different areas of brain to work together. Manages singles brain sends
Cerebellum involved in making postural adjustments to maintain balance