NS 19 - proprioception Flashcards
define proprioception
awareness of position of body parts in relation to each other and surroundings
list the type of proprioceptors in the masticatory system
- muscle spindles (within body of muscle)
- golgi tendon organs (within the tendons)
- joint receptors
what type of msucle fibres are the bulk of muscle fibres?
extrafusal (contractile)
what are intrafusal fibres made up of?
muscle spindle
specialised muscle fibres within CT capsule
describe the basic structure of a muscle spindle
2 contractile ends at either side and a non - contractile central portion which can be stretched
which nerve supply allows for contraction?
motor nerve supply
what part of the spindle is supplied by gamma neurones?
end parts - the contractile ends
what is the rest of the muscle spindles supplied by?
A alpha motor neurones
which nerve detects length of fibres and the speed of change in length?
primary annulospinal nerve ending
what supplies the extrafusla fibres?
alpha motor neurones
what is the role of muscle spindles?
info about muscle length and act to maintain muscle length
why would you always get some activity in the spindle regardless of what happens to the afferents?
there is always always an element of stretch so you would always get some activity from the spindle
where are the muscle spindle cell bodies?
mesencephalic nucleus
where do muscle spindle afferents synapse?
V motor nucleus
list the functions of gamma motor neurones
- contraction of intrafusal fibres
- maintain tension in spindle
- maintain spindle afferent activity
- alpha-gamma activation
function of golgi tendon organs
- in tendons with muscle fibres
- very few if any in masticatory muscles
- tension receptors
- role in inhibitory reflex - prevention of XS stretch of mucle
what is the function of joint receptors and where are they found?
- pacinian - in ligaments - acceleration
- golgi - in ligaments - position
- ruffini - in capsule - movement
what are the tests of proprioceptive ability?
- ability to reposition the jaw
- accuracy of the order of <2mm
- receptors; muscle spindle, tmj receptors PDLMs as there is no tooth contact
