Muscle reflexes: Control of posture Flashcards
How does the feedback loop work?
Muscle spindle detects length in a muscle
Feeds to spinal cord
sends effector to muscle
What is a length trasnducer
Spindle in parallel with muscle
What are intrafusal fibres
designed to monitor length in muscle
contractile elements are gone
What innervates intrafusal fibres
Innervated by type 1a (thick and II (thin) for sensory inn
innervated by dynamic and static gama efferernts for motor inn
How do fibres sense velocity
Fast adapting and very quickly stop firing as soon as stimulus ends
produce a phasic response
What is meant by alpha-gamma coactivation
Contract muscle with alpha motor neurone also contract spindle with gamma motor meurone
What does the alpha- gamma coactivation do?
Prevents spindle from being unloaded
gamma neurones can determine how toned the muscles are
What is the stretch reflex
Monosynaptic reflex but recriprocal innervation
muscle contracts against stretch
smooths and damps muscle movement
signals length and velocity of muscles centrally via the spinocerabellar adn dorsal tracts
What does the golgi tendon organ insure?
tendon doesn’t stretch and allows us to control muscle force finely aswell as length
What is the crossed extensor reflex
An opposite side to stimulus to stiffen the body and stabilise posture
What happens when we are walking
- alternate contraction of flexors and extensors
central pattern generator in spine