Sensory and motor innervation of muscle Flashcards
(20 cards)
where does the motor cortex get regulatory input from?
basal ganglia, cerebellum and somatic sensory regions
what is the function of the motor cortex?
planning, initiating and directing voluntary movement
what is the role of the cerebellum in movement?
co-ordination of sensory and motor aspects
what is the benefit of having interneurons between UMN and LMN?
allows some spasticity to recover function in case of damage
why is it important for some neutrons to descend ipsilaterally
allow postural muscles of the trunk to work in co-ordination with their counterpart. this is not required in eg. muscles of the limbs
what are the 2 types of motor neurons?
alpha motor neurons and gamma motor neurons
what are the functions of the 2 types of motor neurons?
alpha - generation of force
gamma - proprioception
why are collateral axons needed?
space restrictions - not possible to have a 1:1 ratio of cell bodies to axons in the spinal cord
what is a motor neurone pool?
the group of alpha motor neurons that innervate a particular muscle
what is a motor unit?
one alpha motor neurone and all the muscle fibres that it innervates
what does the force generated by the muscle depend upon?
the size of the muscle unit
what is a muscle spindle?
the sensory apparatus of the muscle
what is the function of muscle spindles?
detect changes in muscle length, therefore lies parallel to muscle spindle. proprioception
why do the muscle spindles and alpha motor neurons interact?
to ensure muscles are always under some degree of stretch. this is called muscle tone
what are the 2 different types of spindle fibres?
chain - give information about static response (maintain contraction)
bag - give information about the dynamic response of muscles
which neurons innervate the extrafusal and intrafusal muscle fibres?
extrafusal - alpha
intrafusal - gamma
what is the golgi tendon organ?
a mechanoreceptor, that detects changes in muscle tension, because when the muscle contracts, the force generated acts directly on the tendon. contributes to proprioception
what is an isometric contraction?
tension without a change in muscle length
what id an isotonic contraction?
change in muscle length but not tension
what are the symptoms of upper motor neurone syndrome?
after several days -
- babinski sign
- spasticity
- hyporeflexia
- loss of fine movements
