Tmj

Question 1

What’s the meaning of ginglymoarthrodial ?

Answer 1

Ginglymus : joint that allow mandible to rotate like a hinge against skull base .

Arthrodia : capability of entire mandible to bodily move or glide a bit forward of from side to side ( translational movement ) .

Question 2

How does TMJ formed ?

Answer 2

Articulartion between mandiblar condyle and temporal bone ( glenoid fossa ) with its adjacent articular eminence (ridge) .

Articular disc interposed between this 2 parts.

This 3 parts enclosed by fibrous CT .

Question 3

What’s the shape of mandibular condyle ?

Answer 3

Rounded from front to back and from side to side , the round end of each end allows the condyle to fit in articular fossa .

Question 4

What’s articular eminence ?

Answer 4

Forms anterior border of articular fossa .

Question 5

Why do we call fossa non-functional part ?

Answer 5

When teeth are in tight occlusion there is no forceful contact between head of condyle and concave part of articular fossa .

Question 6

What’s disguinsh the functional region of each condyleand eminence , and where is this region , is the contact direct or indirect ?

Answer 6

Is padded with a thick layer of thought fibrous tissue an area that no blood vessels or nerves .

This fibrous tissue is particularly thick on the surface where function occurs .

Between superior and anterior surfaces of the condyle and posterior surface of articular eminence .

Contact is only indirect , since an articular disc is normally interposed between 2 functioning bony elements .

Question 7

What’s articular disc ?

Answer 7

Tough pad of dense fibrous CT that act as a shock absorber between mandibular condyle and articular fossa and articular eminence

its stabilize the condyle by filling the space between different contours of the condyle and the articular fossa and articular eminences .

Divides the space between condyle head and articular fossa into upper and lower joint spaces .( upper and lower synovial cavities ) , this cavities permit complex functional movements of the mandible .

Question 8

Why does the disc doesn’t found in prepared dry skull ?

Answer 8

Because the disc isn’t bone

Question 9

When mandible moves during function , the right and left disc normally moves at the same time why ?

Answer 9

Because the muscles that pull the jaw forward are attached to the mandibular condyles as well as to the disc .

Question 10

What’s proprioceptive fibers and there function ?

Answer 10

“Receptors for self “
Give detailed and continuous information about the position of limbs and other body parts in space .

In the disc help regulate movements of the condyle by unconsciously determining the position of the mandible.

Question 11

What’s the fibrous capsule ?

Answer 11

Enclosed the jaw and limits its movement .

Question 12

What’s the structural components of fibrous capsule and function ?

Answer 12

Internal surface lined with a synovial membrane , that secretes very slippery synovial fluid that lubricate and nourishes the fibrous covering off articulating surfaces and center of the disc that lack a blood supply .

Question 13

Which type of movement occurs within the lower joint spaces ?

Answer 13

Movement between the heads of the condyles of the mandible and the inferior surface of the disc .

Hinge-type or rotary motion around a hinge axis line .

Question 14

Explain how rotational movement occurs :

Answer 14

Body of the mandible rotates around an imaginary horizontal axis line that connect both condyles .

Question 15

Explain how rotational movement occurs :

Answer 15

Body of the mandible rotates around an imaginary horizontal axis line that connect both condyles .

Condyles rotate within the socket .

Question 16

The purely rotational movement of 2 condyles around a horizontal axis can be compared to what ?

Answer 16

To a playground swing with 2 supporting chains (similar to supporting rami ) that rotates front to back around a supporting pole( the swings horizontal bar , or the axis line that passes through the right and left mandibular cindyle ).

The seat of the swing , like mandible body moves quite big whereas the highest chain links ( like head of condyles ) move little since they are at the axis of rotation .

Question 17

At which level of mandible opening rotational movement is allowed , and when this type of movement is possible ?

Answer 17

When mandible open up to half way ( 12mm of incisors separation) or 22.4 opening.

Occurs around a hinge axis , is possible only when the mandible is not being pulled forward.

Question 18

In which part of joint does the upper joint space moves ?

Answer 18

Movement between the superior surface of the disc and the articular fossa and eminence .

Question 19

Which type of mouth opening and how much and what’s the movement called when upper space take part ?

Answer 19

When open and close the mouth beyond about half way ( beyond the limit of purely hinge-like movement ) .

Mandibular condyle and disc together translate or glide forward ( when open ) , backward when close.

Question 20

Which type of mouth opening and how much and what’s the movement called when upper space take part ?

Answer 20

When open and close the mouth beyond about half way ( beyond the limit of purely hinge-like movement ) .

Mandibular condyle and disc together translate or glide forward ( when open ) , backward when close.

Question 21

What does translation means ?

Answer 21

Bodily movement of the entire mandible and disc downward and forward into the articular eminences.

Question 22

What’s happen to the horizontal axis between the condoles during translation ?

Answer 22

Moves forward as the condyles and discs slide from the articular fossa over the adjacent eminences .

Taking the entire playground swing set with its horizontal bar .

Question 23

What’s happen when the condyles and discs don’t move forward simultaneously ?

Answer 23

The result will be crepitation ( crepitus ).

Question 24

What’s happen when the condyles and discs don’t move forward simultaneously ?

Answer 24

The result will be crepitation ( crepitus ).

Question 25

What’s crepitation , and what’s the cause sometimes ?

Answer 25

Crackling or snapping sound (grating noise ) or noise emitted from TMJ because of disharmonious movement of mandibular condyles against the articular discs ,
sometimes , erroneously thought to be caused by the rubbing together of dry synovial surface of joints .

Question 26

When does crackling noise is heared and when we must take care ?

Answer 26

When heared the articular disc may be snapping in or out of position .
Crepitation doesn’t normally require treatment unless it’s accompanied by pain , limited jaw opening , trismus .

Noise may disappear with time or it may persist for many years being no more than noisy annoyance ( its mean that retrodiacal tissues in there place ) .

Question 27

With practice if a persons who has crepitus on one or both sides what we most learn them ?

Answer 27

Learn to open the jaw like a hinge without protruding it forward , the condyle will be able to rotate beneath the disc and the noise will stop .

Question 28

When person continuous to open beyond about half way which type of movements take places ?

When it begin and when it ends ?

Answer 28

Both translators and rotational opening movement , beginning when the jaw exceeds the maximum hinge opening limit and continuing until the jaw is opened all of the way .

Question 29

In which type of movement sound occur ?

Answer 29

Translation movement
As condyle move forward and slide down onto the articular eminences

Question 30

The sound is sign of what ?

Answer 30

Of dysfunction within the joint , disc that doesn’t follow the movement of condyle

Question 31

What’s the curved path that dictated in combination of hinge and translators movement ?

Answer 31

Movement of the condyle against the posterior and inferior surface of the articular eminences because no conscious effort is being made to open in a retruded manner