Neurophysiology - Jaw reflex Flashcards
What are 3 types of stimuli for inhibitory jaw reflex?
mechanical or noxious stimuli inside mouth
noxious stimuli around mouth
noxious stimuli elsewhere on body
What are the responses of inhibitory jaw reflex?
activation of jaw opening muscles (sub-primates only)
inactivation of jaw closing muscles (only response in primates)
What jaw reflex do the primates have?
inhibitory jaw reflex - inactivation of jaw closing muscles
= jaw opening reflex
What are the 2 phases of the jaw opening reflex
early - 10-30ms
late - 40-90ms
What are the 2 types of pathway for inhibitory jaw reflex?
trisynaptic or polysynaptic
What is an example of an inhibitory jaw reflex?
tooth tap
Why are there 2 inhibitory jaw reflexes when you tap on a tooth?
it activates both nociceptors and mechano-receptors
mechanoreceptor pathway shuts down the trigeminal motor nucleus pathway which is clenching the jaw. the descending pathway
the jaw closes again
the nociceptor pathway then shuts down the descending pathway from the trigeminal motor nucleus and jaw opens
it isn’t as clear cut and the pathways can interchange
Where are the cell bodies for the first order neurones?
trigeminal ganglion (PNS)
Why is the trigeminal motor nucleus activated in this experiment?
the patient is keeping tension slightly biting an during the massester muscle to do so
What reflex will you get with a gentle tap of the tooth?
early reflex, 1 reflex
What reflex will a hard tap of the tooth involve?
early and late reflex
What reflex is there with a sharp electrical stimulus to lip?
late reflex, only connected to the reticular formation pathway
What CNS nucleus is associated with early reflex?
supra-trigeminal nucleus
What CNS nucleus is associated with a late reflex?
reticular formation
What is the role of the inhibitory jaw reflex?
protective function
- prevent overloading of: periodontium, masticatory muscles, TMJ
- FACILITATE JAW OPEIING TO EXCPEL NOXIOUS MATERIAL (FISH BONE)
FACILITATE JAW OPEIING TO MINIMISE DAMAGE TO LIPS
