Lecture 2 Pt 2 Flashcards
Motor side of muscles involves __________ fibers
extrafusal fibers
Sensory side of muscles involves __________ fibres and ___________
intrafusal fibers/ muscles spindles
golgi tendon organs
What are extrafusal fibres?
the contractile elements of the muscle, served by alpha motor neurons
What are intrafusal fibers
muscle length detectors, respond to stretch by exciting alpha motor neurons (preventing damage)
Golgi tendon organs respond to ____________ in muscles by inhibiting alpha motor neurons
increased tension
What comprises a motor unit?
alpha motor neuron + all extrafusal muscle fibers it innervates
If a motor unit has a low innervation ratio, what dos that mean
It means a low number of muscle fibres are innervated by one motor neuron, so the muscle has fine control
T or F: each muscle fiber is innervated by only one axon
False - each muscle fiber is innervated by more than one axon, allowing flexibility in how the muscle contracts
The strength of force generation of an entire muscle is determined by what?
the number of motor units activated
Describe the process of re-innervation of motor neurons
The motor units that are not affected, tend to take over and reinnervate the muscle fibers that belong to a damaged unit
What is an isotonic contraction
the muscle length changes, keeping a constant tension (concentric and eccentric)
What is an isometric contraction?
the muscle maintains the same length, and tension builds up (no movement)
Why do we need to be cautious about force measurements?
In an OME they are subjective
The gamma motor neurons control the sensitivity of ____________ during contraction
muscle spindles
What 3 things is the gamma motor system responsible for?
muscle tone, proprioception and reflexes
