Neurophysiology - Mastication Flashcards
What do you call mastication?
Ingestion
What is stage 1 and 2 of ingestion?
- Transport
Food from lips to cheek teeth (molars,
Premolars)
Mastication - Transport
Food from check teeth to back of tongue
To back of tongue - bolus formation
Swallowing
What is the role of mastication?
Breakdown food
Stimulate salivary flow
Contribution of taste and smell by releasing chemicals
Growth and maintenance of oro-facial tissues
How necessary is mastication for absorption in the gut?
Very important
Read meat and vegetables need mastication to be absorbed
What food don’t fully rely on mastication for absorption?
White meat
Fish, eggs rice bread cheese
Why is mastication important for dentist to know?
Poor dentition, poor mastication
Have more but disorders, does not mean one is leading to the other
How is gut health and poor dentition related?
Poor dentition leads to gut disorder
Poor diet leads to poor dentition and gut disorders
Poor dentition leads to avoidance of high fibre food - poor gut health
Not cause and effect but clear relation
What can overlap with mastication in humans?
Swallowing
What are the 2 sequences of swallowing?
Mid-sequence (swallowing during chewing)
End-sequence
What is the chewing cycle?
Opening
Closing -
Intercuspal
What are the two stages in the closing phase?
Fast (crushing phase)
followed by:
Slow (grinding phase)
What are the phases in intercuspal phase?
Contact
Tooth-food-tooth
Tooth-tooth
How long is the chewing cycle?
0.5 to 1.2 secs
What is bolus formation?
Bolus formation ensures that when the food mass is swallowed, it will pass the pharyngeal region safely without risk of inhaling small particles into the lower respiratory tract.
Crucial for bolus formation is food particle size reduction by mastication.
This allows the tongue to pack particles together tightly by pressure against the hard palate.
What movements contribute to the mechanics of mastication?
jaw movements
lip movements
tongue movements
cheek movement
What is 1 chewing cycle?
opening + closing + power stroke
What is chewing sequence?
numerous chewing cycle
What is the working side and balancing side?
working side = functional side
- to which mandible moves
- where food is located
balancing side = non-functional side
- from which mandible moves
What is opening of the teeth during the open phase? (antyerior and posterior)
anterior 16-18mm
posterior 10mm
How many mm is the shift towards the working side?
5-6mm
Put these phases in order:
close
shift towards working side
open
open
shift towards working side
close
What is the movement of the condylar head during opening? (working and balancing side)
working side head:
- rotates
- moves slightly (1-1.4mm) laterally
balancing side:
- moves downwards, forwards and medially
Bennett movement?
Lateral movement of the mandible
What is the movement of the condylar head during closing?
working side:
- moves medially (back to normal position in glenoid fossa)
- rotates back to normal orientation
balancing side:
- moves upwards, backwards and laterally (back to normal position in glenoid fossa)
What is the angle called from the resting position on the balancing side to the open position on the balancing side?
bennett angle (BG)
What does the bennett angle measure?
how much the balancing side has moved forward and inward (medially)
Who has a wider bennett angle?
elderly people with shallow teeth
What is abnormal about the chewing cycle on the left?
lateral movement then downward movement
What is abnormal about the chewing cycle on the right?
- usually a dislocation in TMJ
What do chewing cycle patterns vary with?
food consistency
quality and quantity of tooth contact
presence or absent of pain
What can make a chewing cycle have a more vertical chewing stroke?
tall cusps and deep fossa
What can cause a chewing cycle to be broader?
flattened or worn teeth
What chewing cycle is present if there is pain?
shorter, slower and irregular pathway
What is masticatory performance?
the ability to break down morsels into small particles
OR
the number of chewing strokes required to prepare a mouthful for swallowing
What is masticatory performance correlated with?
correlated with total contact area
What is the pink are?
occlusal contact area
What happens when occlusal contact area drops to 20% ?
masticatory performance decreases drastically
When does the occlusal contact area decrease to 20%
if the molars and premolars are lost
What movements control mastication?
voluntary movements, reflex movements and cyclical movements
What is the seen on the EMG during slow closing phase?
the masseter EMG is even more active
There is overlap between the slow closing and opening on the EMG, why is this?
smooth cyclical movements
otherwise very mechanical - open, close, open close…
Is the slow closing EMG working harder of less hard than fast closing?
working harder than fast closing
why is the slow closing working harder than fast closing? (EMG)
coming into contact with food more so than fast closing phase
teeth coming closer together
periodontal receptors
lip and mucosa receptors
muscle spindle receptors (contributing to jaw jerk reflex)
What receptor is active during opening phase?
muscle spindle receptors
What is the sequence of muscle activation in opening?
mylohyoid
digastric
lateral pterygoid
What is the sequence of muscle activation in closing?
(lateral pterygoid also active)
temporalis
masseter
mal pterygoid
How is the lateral pterygoid active during opening and closing?
2 heads, one attached to the neck of condylus and one to the cartilage
opening: lower belly is pulling down the neck of the condylar, assisting in moving the jaw downward and forward
closing: upper belly is active, is pully the disc down t keep it at the top front position of the condylar to stop it slipping backward
