Control of Mastication Flashcards
What is the role of mastication?
Breakdown of foodstuffs:
- preparation for swallowing
- increase surface area for chemical digestion
- release of chemicals for sense of taste
- stimulation of salivary flow
- growth and maintenance of orofacial tissues
What does the chewing cycle consist of?
When does chewing occur?
- 0.5-1.2 secs duration
Phases:
- opening
- fast closing
- slow closing
- intercuspal phases
Chewing occurs during slow closing and intercuspal phases
What is the sequence of muscle activation during:
- opening?
- closing?
Opening:
- mylohyoid
- digastric
- lateral pterygoid
Closing:
- temporalis
- masseter
- medial pterygoid
What is reflex latency?
What affects this?
What can be used to measure reflexes?
Reflex Latency: time from activating receptor with stimulus to getting an effect in effector tissue e.g. muscle
- conduction time: neurone speed and distance
- minimum synaptic delay = 0.2ms per synapse
Electromyogram: attach electrodes over masseter, pick up electrical activity seen in muscle during contraction, can be recorded onto a screen
What is the role of stretch reflexes?
Tonic - minimal muscle activity
- resist gravity, help maintain jaw posture
Phasic - happens in bursts
- load compensation during chewing, stabilises jaw during vigorous head movements e.g. during running
What is the human response to a jaw opening protective reflex?
What is the role of the inhibitory jaw reflex?
- inactivation of jaw closers
- cessation of closing
- inhibitory jaw reflexes
Role:
- prevent overloading of the masticatory system
- facilitate opening: expel noxious material, minimise damage to intra-peri-oral structures
