TMJ Biomechanics Flashcards by Connor Vankouwenberg

How many joints comprise the TMJ

How well did you know this?

Not at all

Perfectly

What are the 4 joints of the TMJ

2 rolling glide joints and 2 planar joints

How well did you know this?

Not at all

Perfectly

What are the 2 rolling glide joints

Lower joints

How well did you know this?

Not at all

Perfectly

What are the 2 planar joints

Upper joints

How well did you know this?

Not at all

Perfectly

What does each TMJ consist of (3)

Mandibular condyle
Articular eminence of temporal bone
Articular disc

How well did you know this?

Not at all

Perfectly

What forms the hinge joint of the TMJ

Mandibular condyle and the inferior surface of the disc

How well did you know this?

Not at all

Perfectly

What forms the plane/gliding joint of the TMJ

Articular eminence and superior surface of disc

How well did you know this?

Not at all

Perfectly

What type of joint is the TMJ

Synovial joint

How well did you know this?

Not at all

Perfectly

What type of cartilage does the TMJ have

Fibrocartilage

How well did you know this?

Not at all

Perfectly

What does fibrocartilage allow for

Healing properties

How well did you know this?

Not at all

Perfectly

True or False:

The TMJ is capable of being very strong and powerful, but very delicate and precise at the same time

True

How well did you know this?

Not at all

Perfectly

True or False:

You will see lots of TMJ problems in the clinic

False

How well did you know this?

Not at all

Perfectly

Is the articular disc of the TMJ free floating

Nope

How well did you know this?

Not at all

Perfectly

What holds the disc in place

Anterior side: Lateral pterygoid superior head

Posterior side: Retrodiscal bilaminar tissue

How well did you know this?

Not at all

Perfectly

How many layers of laminar rings does the retrodiscal tissue have

How well did you know this?

Not at all

Perfectly

What is the thickness of the disc in the TMJ

Thick, thin, thick

How well did you know this?

Not at all

Perfectly

Where is the thinnest portion always located

The middle of the disc

How well did you know this?

Not at all

Perfectly

How do you palpate the coronoid process and temporalis

With the mouth open

How well did you know this?

Not at all

Perfectly

Where is the coronoid process located when the mouth is closed

Under zygomatic arch

How well did you know this?

Not at all

Perfectly

Is the mandibular fossa thin and translucent or thick and opague

Thin and translucent

How well did you know this?

Not at all

Perfectly

Why is the mandibular fossa thin and translucent

Because no compression occurs there (Wolff’s Law)

How well did you know this?

Not at all

Perfectly

What type of bone is the articular eminence

Trabecular

How well did you know this?

Not at all

Perfectly

What orientation does the mandible and articular eminence have

Convex on convex

How well did you know this?

Not at all

Perfectly

Where is the most fibrocartilage found in the TMJ disc

Articular eminence and anterosuperior condyle

How well did you know this?

Not at all

Perfectly

How are the deep fibers aligned in the disc

Perpendicular

How are the superficial fibers if the disc aligned

Parallel

What is the shape of the articular disc of the TMJ

Biconcave

What is the configuration of the TMJ joint

Convex condyle on concave inferior disk and concave superior disc on convex articular eminence

Is the disc firmly attached to the capsule medial and lateral

What does the disc not being attached firmly to the capsule allow

Free rotation of disc with condyle

What does the lateral pterygoid restrict

Posterior translation

What does the bilaminar retrodiscal tissue restrict

Too much anterior translation of the disc

Are the bilaminar retrodiscal tissues or lateral pterygoids tense when the TMJ is at rest

Negative

What happens to the disc when you close your mouth

It shifts ever so subtly anteriorly or posteriorly

Why does the disc shift at rest

For repair

What is the thickness of the disc anteriorly, posteriorly, and middle

Anterior: 2mm Posterior: 3mm Middle: 1mm

True or False: | The anterior and posterior portions are vascular and neural

True

True or False: | The middle portion is avascular and aneural

True

What are the 3 functions of the articular disc

1. Increased congruency of joint surfaces 2. Shape allows for greater flexibility of disc 3. Thick, thin, thick provides self centering mechanism

What does greater flexibility of the disc allow for

To conform to the bony surfaces with rotation and translation arthrokinematics

If you increase pressure how does the disc rotate

So the thin portion is between the articulating surfaces

If you decrease the pressure how does the disc rotate

To either wider portion

What are the muscles that act on the TMJ (6)

1. Anterior digastric 2. Posterior digastric 3. Medial pterygoid 4. Lateral pterygoid 5. Temporalis 6. Masseter

What are the muscles that cause mandibular depression (3)

1. Inferior head of lateral pterygoid 2. Anterior digastric 3. Posterior digastric

What is the norm for mandibular depression

40-55mm

What happens to the superior head of the lateral pterygoid during depression

Goes on slack

How do the anterior and posterior digastrics cause mandibular depression

Posterior digastric contracts isometrically and anterior digastric contracts concentrically

What muscles cause mandibular protrusion (3)

1. Massester 2. Medial pterygoids 3. Lateral pterygoids

What muscles cause mandibular retrusion (2)

1. Posterior temporalis | 2. Anterior digastric

What muscles cause mandibular lateral deviation (3)

1. Ipsilateral temporalis 2. Ipsilateral lateral pterygoid 3. Contralateral medial pterygoid

What is the axis of rotation during lateral deviation

Ipsilateral condylar process

What is a force couple

Parallel and opposite direction of forces that cause rotation

What are the arthrokinematics of mandibular depression

Initial anterior roll followed by anterior inferior translation of the disc and condyle

During mandibular depression when does the anterior ad inferior translation occur

Near full opening

How does the ICR shift during mandibular depression

Anteriorly

How much of the mandibular depression comes from the condyle rotation

11-25mm

Where does the rest of the mandibular depression come from

Disc and condyle translating

What does the muscle being adaptively shortened limit

Agonist direction

What does the muscle being organically weak limit

Antagonist direction

True or False: | You should have compression loading of tissues

False

What do we as PTs enhance the roll or the translation

The translation

What are the arthrokinematics of mandibular elevation

Initial posterior and superior translation of disc and condyle followed by posterior roll of condyle

How does the ICR shift during mandibular elevation

Posteriorly

What are the arthrokinematics of mandibular protrusion

Bilateral condyle translation anterior and inferior

What are the arthrokinematics of mandibular retrusion

Bilateral condyle translation posterior and superior

What is the norm for mandibular protrusion

6-9mm

What is the norm for mandibular retrusion

3mm

What are the arthrokinematics of mandibular retrusion from neutral

Posterior translation

What is the norm for mandibular lateral deviation

8mm

What is the normal "freeway" when the mandible is in the resting position

1.5-5mm

What does firm approximation of the upper and lower teeth equal

Occlusal position

What is another name for an occlusal position

Bruxated position

What does the resting position allow for

Decreased intra-articular pressure and stress on articular structures

What happens with forward head overtime

Mandible will depress and retrude

What is bruxism

Grinding teeth

What are 5 ways to injure the TMJ

1. Direct trauma 2. Poor posture or oral habits 3. Reciprocal click 4. Locking 5. Osteoarthritis

What causes a reciprocal click

Anteromedial displacement of the disc

When do the clicks occur

First during opening and second during closing

What causes the 1st click

Condyle contacting the anteromedially displace disc

What causes the 2nd click

The condyle leaving the anteromedially displaced disc during closing

What does an early click signify

Less anteromedially displaced disc

What does a late click signify

More anteromedially displaced disc

What happens during locking

Only roll occurs

Does anterior or posterior translation occur with locking

Not at all

Which way is the disc displaced during locking

anteriorly

What causes close locking

Disc is anteriomedial to the condyle

What are the symptoms of closed locking

Cannot open mouth fully

What causes open locking

Disc is posterior to the condyle

What are the symptoms of open locking

Cannot close mouth fully

Is OA of the TMJ usually bilateral or unilateral

Unilateral

Motivation

Just keep swimming. Just keep swimming. Just keep swimming swimming swimming