OB11 - Mastication - Control Flashcards
(23 cards)
how is mastication controlled?
- pattern generator
- voluntary
- reflex
what is a reflex?
Predictable response to a given stimulus
5 examples of reflexes?
- knee jerk
- jaw jerk
- pupillary jerk
- gag reflex
- salivary reflex
describe the reflex pathway (7)
- stimulus
- receptor
- afferent neurone
- synapse
- efferent neurone
- effector
- response
what are the three types of jaw relfexes?
- stretch reflex
- protective reflex
- unloading reflex
what reflexes are usually mono-
synaptic?
stretch reflexes
What is the receptor in the knee jerk reflex?
Muscle spindle
How many synapses are in the knee- jerk reflex?
one
What is the effect of the knee jerk reflex?
Contraction of quadriceps femoris
What is the latency of the knee jerk reflex?
19- 24ms
How long is the minimum synaptic delay?
0.2ms per synapse
What is the effect of the jaw jerk reflex?
Contraction of masseter muscle
What is the latency of the jaw- jerk reflex?
7-8ms
What is the role of the jaw jerk reflex?
It stabilises the jaw during vigorous head movements- e.g during running
What is the name for a polysnaptic reflex which is often a response to a noxious stimulus?
protective reflex
what are the stimuli of the jaw opening reflex?
- Intra‐oral mechanical or noxious
- extra‐oral noxious
what are the receptors of the jaw opening reflex?
Mechanoreceptors and nociceptors
What is the response of jaw opening reflex?
Inactivation of jaw closers
what is the response of inhibitory jaw reflexes?
inactivation of jaw closing muscles
what is the role of the inhibitory jaw reflexes?
- prevent overloading of the masticatory system
- expel noxious material
- minimise damage to intra-/peri- oral structures
What is the stimulus for jaw unloading reflex?
Sudden closure following hard biting e.g a hard/brittle food breaks
What is the response for jaw unloading reflex?
Inactivation of jaw closing muscles and activation of jaw opening muscles
What is the result of jaw unloading reflex?
teeth do not crash together
