TMJ Flashcards

1
Q

What two bones make up the TMJ

A

The temporal bone of the skull (squamous portion) and the condyle of the mandible

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2
Q

What limits the glenoid fossa?

A

The glenoid fossa is limited anteriorly by the articular eminence and posteriorly by the tympanic plate and postglenoid tubercle

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3
Q

What is the superior TMJ joint capsule attachment?

A

The circumference of the glenoid fossa but extending to the anterior of the articular eminence and posterior to the petrotympanic fissure

The temporal bone, superiorly, has to enclose the articular eminence

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4
Q

What is the inferior attachment of the TMJ joint capsule?

A

The neck of the mandible

The capsule encloses the joint space all the way around

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5
Q

Synovial membrane of the TMJ

A

Lines the entire joint space EXCEPT the articular surfaces

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6
Q

What is the function of the synovial membrane

A

It lubricates the joint, and provides nutrients to avascular parts of the joint

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7
Q

What covers the articular surfaces of the TMJ?

A

Dense, fibrous connective tissue

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8
Q

What is the benefit of having dense fibrous connective tissue instead of cartilage?

A

It is much more dynamic and can adapt

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9
Q

When may there be fibrocartilage in the articular surface of the TMJ?

A

Stress bearing areas may have fibrocartilage or fibrous connective tissue with cartilage cells but there will not be fibrocartilage in a mature TMJ

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10
Q

What is the blood supply to the articular surface?

A

No blood supply - it is an avascular surface

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11
Q

What is the primary nerve of the TMJ?

A

Auriculotemporal nerve

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12
Q

Where are the nerve endings in the TMJ?

A

The auriculotemporal nerve has sensory nerve endings in the joint capsule and the retrodiscal pad, pain fibers and some proprioception are supplemented by fibers in the periodontal ligament

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13
Q

What is the primary blood supply to the TMJ?

A

Branches of the superficial temporal and maxillary arteries

The most important is the anterior tympanic branch of the maxillary artery
Maxillary artery provides for the deep side of the TMJ, and the superficial temporal provides for the more lateral side of the TMJ

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14
Q

What is the intrinsic ligament of the TMJ?

A

The lateral ligament of the TMJ, which is also called the temporomandibular ligament.

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15
Q

Where does the lateral ligament of the TMJ attach?

A

From the articular tubercle to the neck of the mandible

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16
Q

What is the function of the lateral ligament of the TMJ?

A

It helps to limit posterior and inferior movement, and is part of the joint capsule itself

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17
Q

What are the extrinsic, or accessory, ligaments of the TMJ?

A

The sphenomandibular ligament and the stylomandibular ligament

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18
Q

Where does the sphenomandibular ligament attach?

A

From the spine of the sphenoid bone to the lingula of the mandible (remnant of meckel’s cartilage) - it surrounds the opening of the mandibular foramen

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19
Q

Where does the stylomandibular ligament attach?

A

From the styloid process to the angle of the mandible

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20
Q

What do the extrinsic ligaments of the TMJ collectively do?

A

Limit inferior and anterior movement

21
Q

Which is the more important of the extrinsic ligaments of the TMJ?

A

The sphenomandibular ligament

22
Q

Articular disc/meniscus of the TMJ

A

Dense fibrous connective tissue with areas of stress sometimes made up of fibrocartilage, it is there for stability and to fill in the incongruities of the joint

23
Q

What makes up the articular part of the disc?

A

anterior and posterior bands and an intermediate zone. between bones during movement

Articular part of disc = avascular

24
Q

Where is the disc attached?

A

The disc is attached to the medial and lateral poles of the condyle of the mandible, and the attachment is very very tight

These attachements are called collateral ligaments

25
Q

Where does the disc merge?

A

Into a capsule around the entire circumference

26
Q

What is the posterior disc (non articular part) called?

A

Retrodiscal pad, or bilaminar zone

27
Q

What part of the disc has nerve endings and vascular tissue?

A

The retrodiscal pad/posterior disc/bilaminar zone/non-articular part of the disc

28
Q

What part of the disc is always thicker?

A

The medial part of the disc is always thicker than the lateral part of the disc

29
Q

What is the most common part of the disc for perforation?

A

Lateral part of the intermediate zone

30
Q

How does the disc fit onto the condyle?

A

Fits onto the condyle like a swim cap

31
Q

What joint space is tight, and what is loose?

A

The lower joint space is tight and allows for rotational movement

The upper joint space is looser and allows for translational movement

32
Q

What compartment between disc and condyle is the site for rotational movement?

A

The inferior compartment

33
Q

What compartment between disc and fossa is the site for translational movement?

A

The superior compartment

34
Q

What is the movement within the joint?

A

The initial opening (first few mm) is rotational, or hinge movement. It is limited by the tympanic plate, the parotid gland, and the retrodiscal pad.

Further opening - the condyle and disc translate anteriorly as a unit onto and down the articular eminence

35
Q

What muscle contracts to allow the mouth to START opening?

A

The lateral pterygoid

36
Q

What is the axis of rotation for the initial opening of the mouth?

A

the axis is IN the condyle

37
Q

Where is “translation” occurring?

A

Between the disc and the articular eminence

38
Q

Where is “rotation” occurring?

A

Between the condyle and the disc

39
Q

What happens to the center of rotation when you want to translate farther?

A

The center of rotation changes from the condyle to the center of the ramus in order to translate farther

40
Q

What is the sequence of moving in opening?

A

Lateral pterygoid contracts to initiate opening; the shortening pulls on the neck of the mandible and starts the rotational movement with the axis of rotation through the condyle

When rotational opening is hindered, the lateral pterygoid pulls the mandible forward onto the articular eminence and down it. The disc moves along with the condyle.

As the stylomandibular and sphenomandibular ligaments are pulled tight, the mandible rotates downward around an axis through the mandibular foramen (i.e. depression - and the sphenomandibular ligament acts as a swinging hinge). There is a shift in axis of rotation - it allows the inferior alveolar nerve and vessels to remain static

41
Q

What is unique about the mandible?

A

It is one bone with two more or less symmetrical joints - the angle allows for lateral movements of the TMJ

A working movement means that it is moving TOWARD that side.

42
Q

Differentiate between what is the rotating condyle and what is the orbiting condyle

A

If you are moving your mandible to the right, the rotating condyle is the RIGHT condyle, and the orbiting condyle is the LEFT condyle

43
Q

What are the changes in the TMJ associated with age?

A

Loss of teeth may lead to perforations of the disc, and flattening of the condyle and eminence

44
Q

Dislocation of the joint - luxation or subluxation

A

Always occurs anteriorly

Locked open, and you cannot move the mandible
Can happen from over-opening, blow to the side of the mandible when the mouth is open

45
Q

Unilateral dislocation

A

Mandible will deviate to one side, away from the effected side

46
Q

How can you decide if it is a bilateral or unilateral dislocation?

A

If the midline of the mandibular incisors is in the right spot, the mandible is dislocated on both sides.

If the mandibular midline is deviated from the maxillary midline, it is unilateral.
If the mandible is deviated toward the right, the dislocation is on the left side

You can reposition by forcing the mandible inferiorly (downward pressure) in order to get it below the eminence

47
Q

Ankylosis

A

fusion of the mandibular condyle to the fossa

fairly uncommon, happens most commonly in kid due to trauma, causes inflammation of the joint and condyle, causing it to fuse together due to inflammation

This is a LONG TERM CONDITION

Deviation in midline due to the fusion, growth on one side has stopped - the deviation is toward the ankylo side

48
Q

TMD - Temporomandibular dysfunction or disorder

A
Symptoms include:
headache
pain, in joint and muscles
clicking joints
earache

40-60% of people probably have symptoms, so it is a common problem but only 5% think it is severe enough to seek treatment

Majority of those who seek treatment are women in late teens, early twenties, and postmenopausal