Motor Control II Flashcards
Alpha Motor Neurons get synaptic inputs from:
- Descending motor tracts
- Spinal interneurons
- Propriospinal neurons
- Muscle spindles
Corticospinal Tract does fine/gross motor
Fine
Reticulospinal tract does fine/gross motor
Gross
What do propriospinal Neurons do
Coordinate body/starting position of upper and lower limbs
Relationship between muscle and motor neuron pools
1 to 1
Muscle Spindles monitor
Muscle length and velocity of contraction (via measuring speed of length change)
Golgi Tendon Organs monitor
Muscle tension
What is in a reflex arc
Mutually connected neurons + effector tissue (muscle)
Monosynaptic Reflex
Just two neurons (sensory and response)
Polysnaptic Reflex
More than two neurons (sensory, response and extra responsive eg. antagonistic, multiple muscles )
Five elements of a reflex
- Receptors
- Afferent fibres
- Central Synaptic Relay
- Efferent fibres
- Effectors
Stretch Reflex 5 Elements
- Receptors = muscle spindles (detect change in length)
- Afferent fibres = Intrafusal 1A
- Synaptic Central Relay = 1A -> aMN
- Efferent fibres = aMN
- Effectors = Extrafusal Skeletal Muscle
Reciprocal Inhibitition
Inhibition of motor neurons of antagonistic muscles
Reciprocal Inhibition Synpatic Relays
- Normal (Afferent to aMN)
- 1A to 1A Inhibitory Interneurons (which then inhibit aMN of antagonist muscle)
Muscle Spindles made of
Collagen
Intrafusal fibres are found in
Muscle spindles
Intrafusal fibres innervated by
Gamma motor neurons
Gamma motor neurons cell body size
Small
What is the function of gamma motor neurons
Keeping muscle spindles at appropriate lengths, so that they shorten with extrafusal fibres when alpha motor neurons evoke that
Golgi Tendon Organ location
Myotendinous junction
Golgi Tendon Organ innervation
Group 1b afferent
Reverse Myotactic Reflex 5 Steps
Receptors = Golgi Tendon Organ
Afferent = 1B
Synaptic Relay = 1B afferent to 1B inhibitory interneuron which inhibits aMNs
Efferents = aMNs
Effectors = Muscle
Purpose of reverse Myotactic reflex
Protect muscle from tension overload by inhibiting aMN of the same muscle, to prevent any more tension from more contraction
Flexor Withdrawal Reflex 5 Parts
Receptors: Nociceptors (pain)
Afferects: Type III and IV
Synaptic Relays: III/IV to excitatory interneurons which excite flexor aMNs
Efferents: aMNs
Effectors: Flexor musles
What happens to the other limb during Flexion withdrawal
Extensors contract, flexors relax (opposite to the withdrawing limb) = maintains balance
