Mastication and Occlusion Flashcards
1
Q
What is the TMJ?
A
Temporomandibular joint
2
Q
What type of joint connects the temporal bone and the mandible?
A
Synovial joint
3
Q
In a synovial joint what is the name given to the cartilage that surrounds the bone?
A
Hyaline articular cartilage
4
Q
Where does the condyle sit in the TMJ?
A
In the glenoid fossa
5
Q
What is the glenoid fossa bounded by?
A
articular eminence
tympanic plate of temporal bone
6
Q
How many layers does the joint capsule have?
A
2
outer fibrous layer
inner synovial membrane
7
Q
What is the purpose of the synovial membrane?
A
secretes synovial fluid to fill the joint spaces
8
Q
what movements does the lateral ligament restrict?
A
posterior, lateral and inferior movement
9
Q
what are the 3 accessory ligaments?
A
pterygomandibular raphe
stylomandibular ligament
sphenomandibular ligament
10
Q
What does the articular disc do?
A
divides the joint into 2 compartments; lower - hinge, upper - slide
11
Q
what are the 5 zones of the articular disc?
A
anterior extension
posterior extension
anterior band
intermediate zone
posterior band
12
Q
what nerve innervates the TMJ?
A
Trigeminal nerve V3
13
Q
what supplies blood to the tmj?
A
superficial temporal artery
maxillary artery
14
Q
what is the result of an anterior disc displacement with reduction?
A
clicking jaw
15
Q
Where would the condyle be to cause a dislocation of the TMJ?
A
anterior to the articular eminence
16
Q
What is mastication?
A
chewing
17
Q
What is the purpose of mastication?
A
preparation for swallowing
increase surface area for chemical digestion
release of chemicals for sense of taste
18
Q
Where do masticatory movements take place?
A
TMJ
19
Q
What are the 3 groups of muscles involved in mastication?
A
skull-mandible
mandible-hyoid
hyoid stabiliser
20
Q
What are the muscles involved the skull-mandible group?
A
massester
temporalis
medial pterygoid
lateral pterygoid
21
Q
what is the origin and insertion of the superficial masseter muscle?
A
origin: zygomatic arch/bone
insertion: angle/ramus of mandible
22
Q
what is the action of the superficial masseter?
A
jaw elevation (closing)
minor protrusive
23
Q
what is the origin and insertion of the deep masseter muscle?
A
origin: inner aspect of zygomatic arch
Insertion: angle/ramus of mandible
24
Q
What is the action of the deep masseter muscle?
A
jaw elevation (closing)
25
What is the origin and insertion of the temporalis?
origin: inferior temporal line and fascia
insertion: coronoid process
26
What is the action of the temporalis?
(anterior fibres) jaw elevation
(posterior fibres) retrusion
27
what is the origin and insertion of the upper head part of lateral pterygoid?
origin: surface of greater wing of sphenoid
insertion: capsule and articular disc of TMJ
28
what is the origin and insertion of the lower head part of lateral pterygoid?
origin: lateral aspect of lateral pterygoid plate
insertion: pterygoid fovea below head of condyle
29
what is the action of the lateral pterygoid?
inferior head: pulls condyle forward, protrusion, assists opening, lateral excursion
superior head: restrusion and closing
30
what is the origin and insertion of the medial pterygoid?
origin: medial aspect of lateral plate and maxillary tuberosity
insertion: medial aspect of ramus/angle of mandible
31
what is the action of the medial pterygoid?
jaw elevation
protrusion and lateral excursions
32
What are the muscles involved the mandible-hyoid group?
geniohyoid
mylohyoid
digastric (anterior)
33
what is the origin of the geniohyoid?
inferior mental spine + inferior genial tubercle
34
what is the action of the geniohyoid?
(hyoid fixed): jaw opening and retrusion
(hyoid not fixed): raise and forward hyoid
35
what is the origin of the mylohyoid?
median raphe
36
what is the action of the mylohyoid?
(hyoid fixed): jaw opening
(hyoid not fixed): raise hyoid and FOM
37
What is the origin of the anterior belly of digastric?
digastric fossa
38
what is the action of the anterior belly of digastric?
(hyoid fixed): jaw opening
(hyoid not fixed): raise hyoid
39
what are the muscles involved in the hyoid stabilisers group?
infrahyoids (sternohyoid, omohyoid, thyrohyoid)
posterior digastric
stylohyoid
40
what other muscles are involved in mastication?
buccinator
obicularis oris
41
Detection of a mechanical stimuli through a peripheral receptor is called.
mechanoreception
42
Which type of reception gives us information about how things coming into contact with the body?
Exteroception
43
Which type of reception gives us information about our self, such as awareness of position?
Proprioception
44
What are the main oro-facial mechanoreceptors?
mucosa (and skin)
periodontal ligament
muscles
joint receptors
45
what do mucosa (and skin) mechanoreceptors tell us?
food texture
46
what do PDL mechanoreceptors tell us?
forces on teeth
47
what do muscle mechanoreceptors tell us?
muscle spindles tell us muscle length
48
What are the 2 classifications of mechanoreceptors?
physiological
anatomical
49
What is the receptive field?
The area/space where a stimulus will affect the receptor
50
Ruffini nerve endings are best found where in the oral cavity
PDL
51
Are the periodontal ligament mechanoreceptors afferent or efferent?
Afferent, Alpha beta axons
52
Where do the cell bodies of the periodontal ligament mechanoreceptors reside to?
V ganglion, then to the mesencephalic nucleus
53
Innervation density is at its highest, in which region of the periodontal ligament
higher at apex
54
Tooth must move around a what? to detect adequate stimulus?
fulcrum
55
Which region of the tooth would you expect to find slowly adapting, low threshold mechanoreceptors?
apically
56
Which region of the tooth would you expect to find rapidly adapting, high threshold mechanoreceptors?
Cervically
57
What are the 4 stages of the sensory pathway?
Sage 1: mechanoreception
Stage 2: Processing at first synapse
Stage 3: Processing in thalamus
Stage 4: conscious perception
58
What happens at stage 1 of the sensory pathway?
mechanoreceptors have been stimulated and propagation along primary afferent nerve
59
What happens at stage 2 of the sensory pathway?
sensory stimulus are processed at the first synapse at the trigeminal nuclei.
60
What happens at stage 3 of sensory pathway?
Sensory stimulus is processed in the thalamus.
61
What happens in stage 4 of sensory pathway?
Sensory stimulus is processed in the cerebral cortex for conscious perception.
62
At what stage does the sensory stimulus leave the peripheral nervous system and enter the central nervous system?
During stage 2, at its first synapse
63
What is proprioception?
A feedback system that allows us to be aware of our own movement
64
What are the 3 receptors involved in proprioception
Muscle spindles
Golgi tendon organs
joint receptors
65
What are extrafusal muscle fibres?
skeletal standard muscle fibres that are innervated by alpha motor neurons and generate tension by contracting, thereby allowing for skeletal movement.
66
What are intrafusal muscle fibres?
skeletal muscle fibres that serve as specialized sensory organs (proprioceptors) that detect the amount and rate of change in length of a muscle
67
how are afferents activated?
by stretch
68
What do secondary (flower-spray) nerve endings detect?
length of fibres
69
what do primary (annulo-spiral) nerve endings detect?
length of fibres and speed of change of length
70
what is the role of muscle spindles?
gives us information about muscle length
act to maintain muscle length
71
Where are the masticatory muscle spindles cell bodies located?
Trigeminal mesencephalic nucleus
72
Were do muscle spindle afferents synapse?
V motor nucleus
73
What happens when the muscle shortens?
Muscle contracted – shortens.
74
Gamma (y) motor neurones cause contraction of which muscle fibres?
Intrafusal fibres
75
What is the purpose of gamma motor neurones?
Maintain tension in spindle and maintain spindle afferent activity
76
Pacinian, Golgi and Ruffini are example of receptors located where?
the joint
77
What is occlusion?
The contact relationship of teeth or equivalent
78
What is articulation?
The dynamic relationships of teeth when in sliding contact
79
What is jaw relationship?
Positional relationship which the mandible bears to the maxilla
80
Vertical jaw relationship and dimensions – our teeth when they are slightly apart by few mm is best known as what position?
Rest/postural position
81
Vertical jaw relationship and dimensions – our teeth when they are together and fully interdigitated?
Intercuspal position (ICP)
82
Is the Intercuspal position stable or not and why?
Not a stable position because, if you were to lose a tooth then the positions would change.
83
Is the rest/postural position a stable position or not and why?
It is a stable position because, it is maintained by minimal muscle activity.
84
In a retruded contact position, describe the position of the condyle?
The condyle is retruded in the glenoid fossa.
85
What is the only muscle that will retract/move back/retrude the jaw?
Temporalis muscle
86
What is the occlusal vertical dimension (OVD)
the face height with the teeth in ICP
87
What two arbitrary points are used to measure the occlusal vertical dimension?
Nose and lower chin
88
What is the rest/postural vertical dimension (RVD)?
face height with the mandible in rest/postural position
89
what two arbitrary points are used to measure the rest/postural vertical dimension?
The nose and the mandible
90
What is used to measure OVD and RVD?
Willis gauge
91
What is the free way space?
gap between your teeth
The difference between teeth in rest position and ICP
92
how do you work out a persons free way space?
RVD-OVD=FWS
93
The restriction of the TMJ is governed by the positioning of the teeth. How does the positioning of the incisors restrict the mandibles movement?
At rest, the incisors will exhibit a slight overbite and overjet, which help restrict movement.
94
The restriction of the TMJ is governed by the positioning of the teeth. How does the positioning of the cusps restrict the mandibles movement?
The Intercuspal position.
95
A wide opening of the jaw exhibits what two movements?
Hinge and slide
96
What does the movement from the ICP to the RCP represent on the border movement graph?
It represents the ICP overcoming the overbite and overjet.
97
From RCP to the next point what does that represent?
This represents the pure hinge (small opening)
98
From RCP to maximum opening what movement would the condyle exhibit?
Hinge and slide
99
What muscle is responsible for moving the muscle forwards?
Lateral pterygoid
100
Is the working side the side to which the teeth move or the side away from which the teeth move?
the side to which the teeth move
101
what is canine guidance?
disocclusion of all the teeth by the contact of unilateral maxillary and mandibular canines only in lateral excursion movement
102
what is group function?
the anterior and posterior teeth have full contact on the working side but no contact on the non-working side
103
what is the position of the condyle on the non working side during excursion?
moves downwards, forwards over eminence, moves medially
104
what is the position of the condyle on the working side during excursion?
rotates around the vertical axis
lateral bodily movement
105
what is the balanced occlusion concept?
tooth contact during excursions at both working and non working sides
106
what is bennet movement?
a complex lateral movement or lateral shift of the mandible resulting from the movements of the condyles along the lateral inclines of the mandibular fossae during lateral jaw movement.
107
What is bennett angle?
The angle formed by the spatial coordinates of the condyles shifts and the sagittal plane
108
how long does the chewing cycle take?
0.5-1.2 secs
109
what are the phases of the chewing cycle?
opening
fast closing
slow closing
intercuspal phases
110
Would there be greater or lesser lateral movements during the chewing cycle if the food was brittle
Lesser lateral movements
111
Would there be greater or lesser lateral movements during the chewing cycle if the food was tougher?
Greater lateral movements
112
What is the sequence of muscle activation in the opening chewing cycle?
mylohyoid
digastric
lateral pterygoid
113
What is the sequence of muscle activation in the closing chewing cycle?
temporalis
masseter
medial pterygoid (lateral pterygoid also active)
114
What is a reflex?
Predictable response to a given stimulus
115
Why is jaw reflex important?
We may bite our tongue and the jaw reflex will help prevent us from ripping off the tongue.
116
What is the stages of jaw unloading reflex?
Stimulus: sudden closure following hard biting
Response: inactivation of jaw closing muscles and activation of jaw opening muscles
Result: Teeth do not crash together
117
Which centre sends a pattern of codes to the motor nucleus which activates specific nerves in a specific pattern which drives the masticatory movement?
Chewing centre
118
Which centre allows us to voluntarily control chewing pattern, through the motor nucleus?
Higher centres
119
What are the three type of reflexes?
Stretch reflex
Protective reflex
Unloading reflex – jaw
120
Which reflex system is the simplest form?
Stretch reflexes
121
Why are stretch reflex the simplest form?
Because it usually is mono-synaptic, meaning it has to synapse once
122
A knee jerk reflex is an example of what type of reflex?
Stretch reflex
123
What is reflex latency?
It is the time taken from the stimulus to the effector. That is usually the length of the pathway.
124
What is the minimum synaptic delay?
0.2 seconds per synapse.
125
Are synapses faster then action potentials
No
126
Muscle spindles act as what in the muscles?
Receptor (afferent, action potentials)
127
What are Temporomandibular Disorders (TMD)?
A group of conditions affecting the temporomandibular joint and/or the muscles of mastication
128
What percentage of people suffer with TMD?
10-15%
129
What age group is most commonly affected by TMD?
18-44
130
Is TMD more common in males or females?
Females
131
What factors make up the aetiology of TMD?
Biological
Psychological
Behavioural
132
What is important to look at when examaning for TMD?
Pain
Noises
Movement
Habits
Trauma
133
How can stress, anxiety and depression all increase the risk of TMD?
Can cause you to grind your teeth more
134
What are 3 co-morbidities that can contribute to TMD?
Fibromyalgia
Chronic pain
Psychological factors
135
What are the stages of a TMD examination?
Palpate the TMJ - lateral pole
Check for noises
Palpate the muscles (temporalis and masseter)
On opening check for deviation and the extent of opening
136
What else could you use to investigate TMD?
CBCT
MRI
137
TMD diagnosis is split into 2 groups, what are they?
Pain related TMDs
Intra-articular TMDs
138
Pain related TMDs are split into 2 groups, what are they?
Myalgia
Arthralgia
139
How does disc displacement with reduction present?
with clicking
140
How does disc displacement without reduction with limited opening present?
Characterised by a history of previous clicking which stops at the same time as the onset of restricted mouth movement
141
What is the TMD classification criteria?
Description
History
Examination
142
How does TMD- Myalgia description present?
Pain of muscle origin provoked when testing of the masticatory muscles
143
How does history of TMD-Myalgia present?
Pain in jaw, temple, infront of ear/in ear
AND
modified with jaw movement or function
144
What does examination of TMD-Myalgia look like?
pain in temporalis or masseter muscle
This pain is reciprocated when:
palpating temporalis or masseter
OR
maximum unassisted or assisted opening movements
145
What are the sub types of TMD-myalgia?
Local myalgia
Myofascial pain
Myofascial pain with Referral
146
How does local myalgia present?
pain is localised to the site of palpation
147
How does myofascial pain present?
pain extends beyond site of palpation but still within the boundaries of the muscle being palpated
148
how does myofascial pain with referral present?
The pain extends beyond the boundaries of the muscle being palpated
149
what is arthralgia?
pain of joint origin affected by jaw movement and replicated by testing of the TMJ
150
What is disc displacement with reduction?
in closed mouth position disc is in an anterior position relative to condylar head and disc reduces on mouth opening
151
What is disc replacement without reduction?
the disc is in an anterior position relative to the condylar head and does not reduce with opening - mouth will not open all the way
152
what is jaw lock
when the mouth does not open all the way
153
what is degenerative joint disease in the absence of pain termed?
osteoarthrosis
154
what is degenerative joint disease with arthralgia accompanying crepitus known as?
osteoarthritis
155
what is crepitus?
a popping, clicking or crackling sound in a joint.
156
what is subluxation
open lock
disc condyle complex lies anterior to articular eminence and cannot be returned to normal position without a manipulative manoeuvre
157
if a patient can manoeuvre the joint back into position what is this called?
subluxation
158
if a patient can't manoeuvre the joint back into position and requires assistance of a clinician, what is this called?
luxation
159
Conservative management of TMD?
rest and relaxation
modify diet
avoid wide mouth opening
regular application of gentle heat - chronic conditions
regular application of cold pack - acute onset pain &/ or restricted mouth opening
Jaw excercises
NSAIDS
diazepam - helps muscle spasms
160
what does FLAT stand for?
Fear of pain
Low mood
Avoidance of functional activities
Thinking the worst
161
what is the purpose of a splint?
Splints are used to allow the muscles and ligaments in the mouth and jaw to relax, and as a result, the facial muscles are able to relieve some of the tension and tightness that may be caused clenching and grinding teeth.
162
what is the purpose of a splint?
Splints are used to allow the muscles and ligaments in the mouth and jaw to relax, and as a result, the facial muscles are able to relieve some of the tension and tightness that may be caused clenching and grinding teeth.
163
what is the aim of a michigan splint?
for maxillary arch
to create:
- canine guidance on lateral excursions
- anterior guidance on protrusion
- posterior disclusion on excursion
164
what is a tanner appliance?
similar to michigan splint but for mandibular arch
165
are stabilisation splints usually worn during the day or at night?
night time
166
how do you make a splint to help with TMD
record when condyle comes forward and jaw protrudes, using hard wax, soften it up and get patient to bite down with their jaw
167
Why should partial coverage splints not be used?
they can cause over eruption on the anterior teeth and a posterior open bite
168
why is the glenoid fossa thin?
so that the forces go through the teeth and not the joint
169
what guides the movement of the condyle?
articular eminence
170
what is canine guidance?
the load is on one tooth
171
what is group function?
the load is shared
172
mandibular moments are guided by what?
TMJ
Teeth
173
what type of articulator is often used in ortho for retainers?
hand held casts
174
what is the downside of hand held casts?
good for simple analysis but you need sufficient teeth
can only be analysed in iCP
175
What is good about a simple hinge articulator?
it relocates the teeth, so is better in a case with a lot of missing teeth
176
what is the downside of a simple hinge articulator
not a good device for simulating anatomical movement
177
what is an advantage of a plane line articulator?
the hinge is more anatomically correct and sturdy than the hand held casts and simple hinge articulator
178
what is the disadvantage of the plane line articulator?
the hinge is still arbitrary - not a simulator of movements
179
What is an advantage of the average value articulator?
has 2 hinges - we have 2 condyles
has a mounting plate - fixed relationship between the glenoid fossa and the jaw
180
what is an advantage of the semi adjustable articulators?
closest relationship to the real anatomy
181
what is required to set up an articulator
face bow/ear bow
182
what do rapidly adapting receptors give information about?
change and only fires when that change happens
