The Temporomandibular Joint Flashcards

1
Q

Name the muscles of mastication

A
  1. Temporalis
  2. Masseter
  3. Medial pterygoid
  4. Lateral pterygoid
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2
Q

What does the Temporalis do?

A

It elevates and retracts the mandible during chewing

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3
Q

What does the Masseter do?

A

Elevates the mandible but can also protrude

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4
Q

Where is the Temporalis?

A

Lies above your temporal bone and attaches to the condyle

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5
Q

Name the strongest of the 4 muscles of mastication

A

Masseter

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6
Q

What does the medial pterygoid muscle do?

A

Mainly elevates the mandible

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7
Q

How can we differentiate between the medial and lateral pterygoid

A

The medal pterygoid muscle runs in the same direction as the Masseter but is found deeper than the Masseter and is a little bit smaller

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8
Q

Where is the medial pterygoid muscle found?

A

Attaches to the medial surface of the lateral pterygoid plate

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9
Q

What is the lateral pterygoid plate part of?

A

The sphenoid bone

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10
Q

What is the lateral pterygoid muscle split into?

A

2 heads:

  1. Superior head
  2. Inferior head
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11
Q

What does the superior head of lateral pterygoid muscle do?

A

It pulls the capsule and disk forward during mouth opening to maintain the relationship between mandibular condyle and TMJ disk
It also stabilises the condyle during chewing

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12
Q

What does the inferior head fo the lateral pterygoid do?

A

It depresses the mandible
Needed in protrusion
Causes lateral movement of the mandible

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13
Q

Where does the lateral pterygoid muscle attach?

A

Attaches to the outer surface of the lateral pterygoid plate

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14
Q

name the foramen found in the sphenoid bone

A
  1. Foramen rotundum
  2. Foramen Ovale
  3. Foramen spinosum
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15
Q

Which nerve passes through the foramen rotundum?

A

The maxillary division of the trigeminal nerve (V2)

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16
Q

Which nerve passes through the foramen Ovale?

A

The mandibular division of the trigeminal nerve (V3)

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17
Q

What makes up the TMJ

A
  1. The condyle
  2. Temporal bone
  3. Disk
  4. Nerves
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18
Q

Where does the TMJ lie?

A

Just anterior to the ear canal

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19
Q

Describe the nerves found in the TMJ. What does this mean?

A

They are nociceptive nerves which means they detect pain

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20
Q

What is the structure of the TMJ describes as

A

A complex synovial joint

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21
Q

What does a synovial joint usually contain

A

Synovial fluid

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22
Q

What are the advantages of having synovial fluid?

A

Acts as a lubricant and provides cushioning

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23
Q

Where does the condyle of the mandible sit?

A

Sits in the mandibular fossa of the temporal bone

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24
Q

Where is the articular disk found?

A

Between the head of the mandible and the bone of the mandibular fossa

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25
What is the aim of the articular eminence?
It prevents the condyle from popping out of the TMJ
26
Where is the articular eminence found?
It is a dip of bone found in the mandibular fossa
27
What is the TMJ separated into?
2 Distinct cavities: Upper joint cavity Lower joint cavity
28
What are the upper and lower cavities of the TMJ separated by?
Fibrocartilaginous articular disk
29
What does the head of the mandible need to do to be able to move your mouth?
Needs to rotate and translate
30
In which direction does the head of the mandible translate
Antero-posteriorly
31
What do hinge movements allow?
Depression and elevation of the mandible
32
What gliding movements allow?
Protrusion/ retraction of the mandible
33
During protrusion what happens?
The teeth , condyles and rami all move in the same direction and at the same degree
34
What does the TMJ have around it?
A capsule
35
Where does the capsule covering the TMJ attach to?
Attaches to the temporal bone superiorly and around the neck of the mandible inferiorly
36
Name some join ligaments found in the TMJ
1. Lateral ligament 2. Sphenomandibular ligament 3. Stylomandibular ligament
37
What is the lateral ligament sometimes called?
The temporomandibular joint
38
Name the 2 parts of the lateral ligament
1. Deep part made up of horizontal fibres | 2. Superficial (outer) part made up of oblique fibres
39
What do the inner horizontal fibres of the lateral ligament do?
They prevent excessive posterior displacement of the head of the mandible
40
What is found posterior to the head of the mandible?
Delicate vascular tissue
41
What can happen if the vascular tissue posterior to the head of the mandible is crushed?
It would comprise the TMJ
42
What can help protect the vascular tissue posterior to the head of the mandible from being crushed?
The inner horizontal fibres
43
Which could break first the inner horizontal fibres of the lateral ligament or the neck of the mandible
Neck of the mandible
44
What do the outer oblique fibres play a role in?
Plays a role in positioning of the condyle (head) as the mouth is opened
45
What do the outer oblique ridges prevent and what does this ultimately lead to?
They prevent the TMJ moving too far due to their limited stretching As a result the head of the mandible moves forwards on to the articular eminence
46
Name the accessory ligaments found on the TMJ
1. Sphemomandibular ligament (SML) | 2. Stylomandibular ligament (STML)
47
Where does the Sphemomandibular ligament run?
Runs from the spine of the sphenoid to the lingual of the mandible
48
What does the Sphemomandibular ligament do?
It supports the role of the outer oblique fibres of the lateral ligament in sliding and prevents excessive inferior displacement
49
Where does the Stylomandibular ligament run?
From the styloid process to the posterior portion of the ramps of the mandible
50
What does the Stylomandibular ligament do?
May limit excessive protrusion of the mandible but the function is unclear
51
Name some parts that attach to the articular disk
1. Superior and inferior joint cavities 2. Anterior capsular ligament 3. Superior retrodiscal lamina 4. Retrodiscal tissue 5. inferior retroediscal ligament
52
What is the anterior capsular ligament part of?
Part of the joint capsule
53
Describe the Superior retrodiscal lamina
It is quite elastic
54
Describe retrodiscal tissue
It is highly vascular
55
What is retrodiscal tissue essential for?
Essential to joint integrity
56
Describe the inferior retrodiscal ligament
Cartilaginous so stron | Inelastic
57
What keeps the articular disk close to the condyle?
The lateral and medial distal ligaments
58
Name the 2 cavities found around the articular disk
Superior cavity | Inferior cavity
59
Which is bigger the inferior or superior cavity?
Superior cavity
60
In which cavity does rotation occur?
Inferior cavity
61
In which cavity does translation occur?
Superior cavity
62
Talk through the stages of normal opening and closing of the TMJ
1. Mandible pushes the disk anteriorly during opening 2. Inferior head of lateral pterygoid pulls mandible anteriorly 3. Mandible head is resting in the articular eminence 4. Superior retrodiscal lamina pulls articular disk posteriorly during closing until all elastic tension has been expanded 5. Articular disk snaps into place in the final stages of closing
63
Give examples of TMJ disorders
1. Clicking | 2. Locking
64
What causes TMJ clicking
Mandible head is in an abnormal position relative to the articular disk (posterior to the disk)
65
What happens in a person with TMJ clicking
1. Opening: The mandible head snaps back into the correct position on the articular diskcausing a clicking noise 2. Closing: The articular disk slips back out of place leading to another click
66
How do we treat TMJ clicking
it usually fixes itself
67
What causes TMJ locking
Mandible head is in an abnormal position relative to the articular disk (posterior to the disk)
68
What happens in a person with TMJ locking
1. Opening: Mandible head does not snap back into the correct position on the disk and is locked in an incorrect position 2. This means opening of the mouth is restricted
69
Name some jaw reflexes
1. Myotactic Reflex | 2. Nociceptive reflex
70
When does the Myotactic Reflex occur?
Occurs continuously to maintain resting position of the mandible
71
What is a Myotactic Reflex?
A stretch reflex where sensory afferent fibres are sent along a trigeminal sensory nerve into the brain stem Sends out efferent muscle fibres to the masseter telling it to contract
72
Why is the nociceptive reflex important
It protects our teeth
73
What is the nociceptive reflex a response to?
A response to pain caused by potentially damaging biting forces
74
What happens in the nociceptive reflex
A stretch reflex where sensory afferent fibres are sent along a trigeminal sensory nerve into the spinal cord Sends out efferent muscle fibres to the digastric muscle teeing it to contract and inhibits the muscles of mastication This allows you mouth to open up
75
What is the end result of a nociceptive reflex
Relaxation of the muscles of mastication and simultaneous contraction of digastric muscle causing the mouth to open