Jaw Reflexes

Question 1

What is a reflex and what is a reflex arch?

Answer 1

• Predictable response to a given stimulus

1. Receptor (PNS)
2. Afferent Neuron (PNS)
3. Synapse(s) (CNS)
4. Efferent Neuron (PNS)
5. Effector (PNS)

Question 2

What’s conduction time?

Answer 2

Neuron speed and distance

Question 3

What are the 2 types of jaw reflexes?

Answer 3

1. Vertical
   - move mandible relative to maxilla in vertical plane
2. Horizontal
   - move mandible relative to maxilla in protrusive, retrusive or lateral direction

Question 4

What’s the role of the jaw-jerk?

Answer 4

Phasic role:

• load compensation during chewing
• Stabilises jaw during vigorous head movements (during running)

Tonic role:

• Resist gravity
• Helps maintain posture

Question 5

How are teeth positioned at rest?

Answer 5

Apart

• Maintained by minimal muscle activity or governed by muscle elasticity

Question 6

Why is the rest position important when creating dentures?

Answer 6

• Important reference position/height with F/F dentures (full upper + lower dentures)

Question 7

What’s the role of inhibitory jaw reflexes?

Answer 7

1. Protection
   - restrain build-up of forces between teeth during mastication = prevents overloading periodontium/masticatory muscles/TMJ