Motor Systems And Locomotion Flashcards
What is the Golgi tendon organ innervated by?!
Ib afferents
What is a motor unit?!
Motto neurones and the innervated muscle
What type of motoneurones go to the muscle?!
Alpha
What neurotransmitter is involved with neuromuscular junctions?!
Acetylcholine
What is the muscle spindle?!
Sensory apparatus of the muscle
Does the muscle spindle lie in parallel or series with the muscle fibres?!
Parallel
What does the muscle spindle detect?!
Detects change in muscle length
What does the Golgi tendon organ do?!
Detects muscle tension or force
What does the muscle spindle enable?!
Regulation of muscle contraction and precisely matches force generation to motor tasks
What type of receptor is the Golgi tendon organ?!
Mechanoreceptor
What does the muscle spindle comprise of?!
Intrafusal muscle
What does extrafusal muscle do?!
Generates force and forms the bulk of the muscle
What is extrafusal muscle innervated by?!
Alpha motor neurones
What is the Intrafusal muscle innervated by?!
Gamma motor neurones
What does the Intrafusal muscle do?!
Acts as a sensory receptor
What happens when an alpha motor neurone is activated?!
The muscle contracts
Muscle spindle slackens and no longer is sensitive to stretch of muscle
What happens when a gamma motor neurone is activated?!
Muscle contracts as does the spindle fibre allowing it to be sensitive to the stretch of the muscle
What is the characteristics of classes I & II for sensory afferents?!
Large diameter
Rapidly conducting
Often mechanoreceptors
What are the characteristics for III & IV for sensory afferents?!
Small diameter
Slow conducting
Often nociceptors and thermoreceptors
What do primary afferents group Ia do?!
Stretch and rate of change in stretch
What do secondary afferents group II do?!
Stretch only
What do group III and above do?!
Nociceptive from muscle
What do group Ib from Golgi tendon organs do?!
Signal force change in muscle
What does the tendon reflex respond to?!
Excess contraction
Does the Golgi tendon organ lie in series or parallel to the muscle fibre?!
Series
Why is the stretch reflex mono somatic?!
No inter neurone
Which reflexes are polysomatic?!
Flexor reflex
Withdrawal reflex
Crossed extensor
What is reciprocal in the stretch reflex?!
Inhibitory - goes to the antagonist muscle to prevent damage
What is the main goal of tendon reflex?!
To cause relaxation therefore it is inhibitory
Is the tendon reflex monosomatic or polysomatic?!
Polysomatic - contains an inter neurone
What does reciprocal innervation of the tendon reflex cause?!
Contraction
What is the sensory receptor in the tendon reflex?!
Tendon organ
When does the withdrawal reflex occur?!
In response to a painful stimuli
Why does the motor neurones ascend and descend in the withdrawal reflex?!
Different sections of the spinal cord innervate different parts of the hamstring muscle = intersegmental
Which reflexes are monosomatic?!
stretch reflex
What is the crossed extensor reflex in conjunction with?!
The withdrawal reflex
Which reflexes share the same stimuli?!
Crossed extensor and withdrawal reflex
Which reflexes are intersegmental?!
Crossed extensor and withdrawal reflex
What are muscle spindles innervated by?!
Group Ia or II nerve fibres
Why is the crossed extensor Contralateral?!
The inter neurones cross the midline of the spinal cord in order to stimulate extensor muscles in the other limb for balance
What do motor units vary in?!
Size
Amount of tension produced
Speed of contraction
Degree of fatigability
Why is the stretch reflex ipsolateral?!
Motor impulse leaves from the same side from which is arose
What is a motor pool?!
All of the motoneurones innervating a single muscle
What does the corticospinal tract descend through?!
Medulla
Midbrain
Pons
Where do motor signals synapse in the corticospinal tract?!
Ventral horn
What is the basal ganglia involved with?!
Selection and initiation of movements
What is the cerebellum involved with?!
Co-ordination of movements
What is the vestibular system involved with?!
Important in postural control
