I have some questions regarding to TMJ

[happyk9]

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I am studying the histology of TMJ. I noticed that there are not too much information online regarding the histology. Now I have some questions. Hope someone can help me to answer these:

1. Are there any undifferentiated mesenchymal cells in the articular disc? If yes, are they spread out or form a layer?

2. If there are some chondrocytes in the articular disc, is this normal aging change or pathological change? How do these cells come from?

3. Only interstitial growth happens in TMJ cartilage, am I right?

4. For the articular surface, what's the difference between the function of fibrocartilaginous zone and the function of articular zone? I mean they both withstand the force of movement.

 

[happyk9]

Please help me. Thank you!

 

[DrGSP]

I am studying the histology of TMJ. I noticed that there are not too much information online regarding the histology. Now I have some questions. Hope someone can help me to answer these:

1. Are there any undifferentiated mesenchymal cells in the articular disc? If yes, are they spread out or form a layer?

UM cells are present during the development of the articular disc and the TMJ in the neonatal life. In an adult the UM cells are present in the fibro cartilage overlying the temporal fossa and condyle....., since these tissues regenerate and undergo remodelling to resist the forces.

2. If there are some chondrocytes in the articular disc, is this normal aging change or pathological change? How do these cells come from?

Presence of chondrocytes in articular disc is due to aging not sure of pathology. This basic tissue is modified according to the age of the subjects and functional requirements. In fetuses and newborns, it is almost completely fibrous and very cellular, while in adults, it is more cartilaginous with significantly reduced cellularity.

3. Only interstitial growth happens in TMJ cartilage, am I right?

This should be Appositional growth at the Condyles which form the part of tmj. Interstitial growth occurs during the growth of the mandible.

4. For the articular surface, what's the difference between the function of fibrocartilaginous zone and the function of articular zone? I mean they both withstand the force of movement.

Fibrocartilagenous zone: Bundles of collagen fibres arranged in crossing pattern and some in radiating pattern. Function- resist against compressive or lateral forces.

Articular Zone: or superficial zone- composed of fibrous tissue. Fibroblasts scattered in avascular layer of type 1 collagen fibres arranged in bundles oriented parallel to articular surface. Connective Tissue contains cartilagenous cells.

Please share some good sources from where you are reading this information. Will help all of us..........

 

[happyk9]

I am studying the histology of TMJ. I noticed that there are not too much information online regarding the histology. Now I have some questions. Hope someone can help me to answer these:

1. Are there any undifferentiated mesenchymal cells in the articular disc? If yes, are they spread out or form a layer?

UM cells are present during the development of the articular disc and the TMJ in the neonatal life. In an adult the UM cells are present in the fibro cartilage overlying the temporal fossa and condyle....., since these tissues regenerate and undergo remodelling to resist the forces.

2. If there are some chondrocytes in the articular disc, is this normal aging change or pathological change? How do these cells come from?

Presence of chondrocytes in articular disc is due to aging not sure of pathology. This basic tissue is modified according to the age of the subjects and functional requirements. In fetuses and newborns, it is almost completely fibrous and very cellular, while in adults, it is more cartilaginous with significantly reduced cellularity.

3. Only interstitial growth happens in TMJ cartilage, am I right?

This should be Appositional growth at the Condyles which form the part of tmj. Interstitial growth occurs during the growth of the mandible.

4. For the articular surface, what's the difference between the function of fibrocartilaginous zone and the function of articular zone? I mean they both withstand the force of movement.

Fibrocartilagenous zone: Bundles of collagen fibres arranged in crossing pattern and some in radiating pattern. Function- resist against compressive or lateral forces.

Articular Zone: or superficial zone- composed of fibrous tissue. Fibroblasts scattered in avascular layer of type 1 collagen fibres arranged in bundles oriented parallel to articular surface. Connective Tissue contains cartilagenous cells.

Please share some good sources from where you are reading this information. Will help all of us..........

Awesome! Thank you very much! Excellent explanation.

I read some description of TMJ histology from Okeson. But it is too basic so I went to a medical library and checked bunch of histology text books. I was so surprised to see little information regarding to fibrocartilage. After reading several books I still have bunch of questions as mentioned above. Thank you very much!

 

[happyk9]

[3. Only interstitial growth happens in TMJ cartilage, am I right?

This should be Appositional growth at the Condyles which form the part of tmj. Interstitial growth occurs during the growth of the mandible..

I am not sure about this. For appositional growth, cartilage must have perichondrium. Fibrocartilage doesn't have perichondrium, so I thought the growth must be from inside which is interstitial. Now I am confused.

 

[DrGSP]

I am not sure about this. For appositional growth, cartilage must have perichondrium. Fibrocartilage doesn't have perichondrium, so I thought the growth must be from inside which is interstitial. Now I am confused.

Condylar cartilage distinguishes itself from both epiphyseal and articular cartilage. It is a secondary cartilage, an articular cartilage present throughout postnatal life, but unlike other articular cartilages undergo adaptive changes in response to external stimuli by appositional growth (exception). UM cells overlying the fibrocartilage migrate and differentiate into immature cartilage cells. The mode of growth in which new cells are added from the periphery by differentiation of UM cells is appositional growth.

 

[happyk9]

Condylar cartilage distinguishes itself from both epiphyseal and articular cartilage. It is a secondary cartilage, an articular cartilage present throughout postnatal life, but unlike other articular cartilages undergo adaptive changes in response to external stimuli by appositional growth (exception). UM cells overlying the fibrocartilage migrate and differentiate into immature cartilage cells. The mode of growth in which new cells are added from the periphery by differentiation of UM cells is appositional growth.

Wow, awesome! Thank you very much!

 

[happyk9]

Condylar cartilage distinguishes itself from both epiphyseal and articular cartilage. It is a secondary cartilage, an articular cartilage present throughout postnatal life, but unlike other articular cartilages undergo adaptive changes in response to external stimuli by appositional growth (exception). UM cells overlying the fibrocartilage migrate and differentiate into immature cartilage cells. The mode of growth in which new cells are added from the periphery by differentiation of UM cells is appositional growth.

Sorry, I have one more question. So above the UM layer toward the articular surface, it is appositional growth as you said above. How about the growth below? The bone below should be endochondral ossification since the deepest zone is the calcified cartilage zone. Am I right? So there are still two kinds of growth here but for different parts (tissues). Am I right?

 

[DrGSP]

Sorry, I have one more question. So above the UM layer toward the articular surface, it is appositional growth as you said above. How about the growth below? The bone below should be endochondral ossification since the deepest zone is the calcified cartilage zone. Am I right? So there are still two kinds of growth here but for different parts (tissues). Am I right?

UM cells from exterior migrate into the condyle to diff. Hence cause appositional growth. Also shows Endochondral ossification as an adaptive change. This is not seen in articular cartilages elsewhere.

 

[happyk9]

UM cells from exterior migrate into the condyle to diff. Hence cause appositional growth. Also shows Endochondral ossification as an adaptive change. This is not seen in articular cartilages elsewhere.

Super! Your explanation is terrific. You must be an TMJ expert. 👍👍👍

 

[DrGSP]

Super! Your explanation is terrific. You must be an TMJ expert. 👍👍👍

Well I am just one among u aspiring to pass my nbde 1 right now.
Reading and understanding is what makes the diff.

Keep posting more tmj queries so all of us can pitch in to solve.....🙂

 

[georgia doc]

thank u both of u for this discussion.................plz advise, just one month left to take the exam..........read from decks and wheelers.......about tmj, is okeson gonna help ...................i am sure, these qs will...........thank u happy k9👍..............when is ur exam?

 

[happyk9]

thank u both of u for this discussion.................plz advise, just one month left to take the exam..........read from decks and wheelers.......about tmj, is okeson gonna help ...................i am sure, these qs will...........thank u happy k9👍..............when is ur exam?

My exam is coming!!!!!

 

[happyk9]

thank u both of u for this discussion.................plz advise, just one month left to take the exam..........read from decks and wheelers.......about tmj, is okeson gonna help ...................i am sure, these qs will...........thank u happy k9👍..............when is ur exam?

Decks is not enough. You need to read Okeson, at least chapter 1, thoroughly.

 

[anekha]

Condylar cartilage distinguishes itself from both epiphyseal and articular cartilage. It is a secondary cartilage, an articular cartilage present throughout postnatal life, but unlike other articular cartilages undergo adaptive changes in response to external stimuli by appositional growth (exception). UM cells overlying the fibrocartilage migrate and differentiate into immature cartilage cells. The mode of growth in which new cells are added from the periphery by differentiation of UM cells is appositional growth.

hi can u plz explain tmj clicking..wen does it actually occurs...

 

[anekha]

Well I am just one among u aspiring to pass my nbde 1 right now.
Reading and understanding is what makes the diff.

Keep posting more tmj queries so all of us can pitch in to solve.....🙂

which zone of articular disc is present bet d condyle and mand. fossa during closed mouth?
is it intermediate or posterior band..

which zone while after opening of mouth wen dere occurs a disc displacement???

 

[kelvinsng]

This should be Appositional growth at the Condyles ??
Is this right??😕

I found a question on the web, that gives a answer that I don't understahnd. Who can explain it?

here, http://orthodontics.case.edu/facialgrowth/tests/fin98_an.html

30. The condyle of the mandible grows by
[SIZE=-1]A. membrane bone growth.[/SIZE]
[SIZE=-1]B. interstitial bone growth.[/SIZE]
[SIZE=-1]C. appositional bone growth.[/SIZE]
[SIZE=-1]D. proliferation of cartilage.[/SIZE]
[SIZE=-1]E. none of the above.[/SIZE]

answer is D. not C, why?

 

[ddsaspi]

hi can u plz explain tmj clicking..wen does it actually occurs...

Clicking noise of TMJ
Internal derangement of the TMJ is present when the posterior band of the meniscus is anteriorly displaced in front of the condyle. As the meniscus translates anteriorly, the posterior band remains in front of the condyle and the bilaminar zone becomes abnormally stretched and attenuated. Often the displaced posterior band will return to its normal position when the condyle reaches a certain point. This is termed anterior displacement with reduction.

When the meniscus reduces the patient often feels a pop or click in the joint. In some patients the meniscus remains anteriorly displaced at full mouth opening. This is termed anterior displacement without reduction. Patients with anterior displacement without reduction often cannot fully open their mouths'. Sometimes there is a tear or perforation of the meniscus. Grinding noises in the joint are often present.

Hope this helps.

 

[ddsaspi]

I am also going through TMJ from various sources, so please suggest as to where are phagocytes present in TMJ,
synovial fluid or posterior part of the disc.

 

[maro3]

I am studying the histology of TMJ. I noticed that there are not too much information online regarding the histology. Now I have some questions. Hope someone can help me to answer these:

1. Are there any undifferentiated mesenchymal cells in the articular disc? If yes, are they spread out or form a layer?

UM cells are present during the development of the articular disc and the TMJ in the neonatal life. In an adult the UM cells are present in the fibro cartilage overlying the temporal fossa and condyle....., since these tissues regenerate and undergo remodelling to resist the forces.

2. If there are some chondrocytes in the articular disc, is this normal aging change or pathological change? How do these cells come from?

Presence of chondrocytes in articular disc is due to aging not sure of pathology. This basic tissue is modified according to the age of the subjects and functional requirements. In fetuses and newborns, it is almost completely fibrous and very cellular, while in adults, it is more cartilaginous with significantly reduced cellularity.

3. Only interstitial growth happens in TMJ cartilage, am I right?

This should be Appositional growth at the Condyles which form the part of tmj. Interstitial growth occurs during the growth of the mandible.

4. For the articular surface, what's the difference between the function of fibrocartilaginous zone and the function of articular zone? I mean they both withstand the force of movement.

Fibrocartilagenous zone: Bundles of collagen fibres arranged in crossing pattern and some in radiating pattern. Function- resist against compressive or lateral forces.

Articular Zone: or superficial zone- composed of fibrous tissue. Fibroblasts scattered in avascular layer of type 1 collagen fibres arranged in bundles oriented parallel to articular surface. Connective Tissue contains cartilagenous cells.

Please share some good sources from where you are reading this information. Will help all of us..........

hi DrGSP thanks alot for this information ,but in no.2 you means that in fetus the disc is dense fibrous c.t and in adult it is fibrocartilage 😕 ,i am sorry this point confusing me?? thanks in advance

 

[ddsaspi]

I am also going through TMJ from various sources, so please suggest as to where are phagocytes present in TMJ,
synovial membrane or posterior part of the disc.

No body answered this Qn and it was stuck in my head, in the meanwhile i stumbled across a sentence in Orbans which said
"Synovial membrane consists of 3 types of internal cells, 1st a fibroblast like rich in RER or B cell, 2nd rich in golgi complex c/ little or no RER k/a A cell. 3rd is between type A and B. "

Above clears the doubt that phagocytes/macrophages are present in synovial membrane.

 

[rose82]

No body answered this Qn and it was stuck in my head, in the meanwhile i stumbled across a sentence in Orbans which said
"Synovial membrane consists of 3 types of internal cells, 1st a fibroblast like rich in RER or B cell, 2nd rich in golgi complex c/ little or no RER k/a A cell. 3rd is between type A and B. "

Above clears the doubt that phagocytes/macrophages are present in synovial membrane.

Thank you everyone for the discussion...I would like to ask what sources are you guys using..other than decks/kaplan/okeson....?

 

[maro3]

in infant TMJ disc is fibrocartilage or dense fibrous C.T?
please someone answer this Q

 

[ibeflossin]

in infant TMJ disc is fibrocartilage or dense fibrous C.T?
please someone answer this Q

I am pretty sure that the articular disc is composed of dense fibrous CT. It should be similar for adults & infants. If you found this from a test question, I believe it is trying to "trick" you. Hope that helps.

For your reference:
http://www.ncbi.nlm.nih.gov/pubmed/10332315

 

[pb2007]

In an ideal occlusal relationship when an exaggerated bennett component is present in lateral jaw movement ,it will have its greatest potential for interference with the
1..mesiodistal positioning of cusp tips ......answer
2..buccolingual positioning of cusp tips
3..position of central fossa
4..depth of the distal fossa
can sumone plz explain the concept behind this ques .😕
is choice 1st correct because on working side the mandibular teeth move towards buccal of maxillaryn maxillary move towards lingual surface of mandibular .???sumone plxz confirm the reasoning .
this ques is frm series A [1979 released exm,ques 31st ]

 

[ddsaspi]

in infant TMJ disc is fibrocartilage or dense fibrous C.T?
please someone answer this Q

Hey it is definitely dense fibrous connective tissue. It is clearly mentioned in okeson.

 

[ddsaspi]

Thank you everyone for the discussion...I would like to ask what sources are you guys using..other than decks/kaplan/okeson....?

Read Okeson very well 1 to 6, go through Orbans also for a little more in TMJ histology, but i guess too many sources on the internet do not serve our purpose as we have to go by reliable sources. Kaplan also covers rest of DA pretty decently , but its not a substitute for the above two.Even if you master i.e . understand and memorize everything in these sources you should be prepared well for the exam. 👍

 

[maro3]

thx you ibeflossin just to be sure

 

[life easy]

Hey ur explanation was awesome........ Can you tell me source.

I have one more question?

What is present beneath the fibrocartilage in the condyle?
Is it dense fibrous connective tissur
Or bone

Please answer. Exam in 15 days

I am studying the histology of TMJ. I noticed that there are not too much information online regarding the histology. Now I have some questions. Hope someone can help me to answer these:

1. Are there any undifferentiated mesenchymal cells in the articular disc? If yes, are they spread out or form a layer?

UM cells are present during the development of the articular disc and the TMJ in the neonatal life. In an adult the UM cells are present in the fibro cartilage overlying the temporal fossa and condyle....., since these tissues regenerate and undergo remodelling to resist the forces.

2. If there are some chondrocytes in the articular disc, is this normal aging change or pathological change? How do these cells come from?

Presence of chondrocytes in articular disc is due to aging not sure of pathology. This basic tissue is modified according to the age of the subjects and functional requirements. In fetuses and newborns, it is almost completely fibrous and very cellular, while in adults, it is more cartilaginous with significantly reduced cellularity.

3. Only interstitial growth happens in TMJ cartilage, am I right?

This should be Appositional growth at the Condyles which form the part of tmj. Interstitial growth occurs during the growth of the mandible.

4. For the articular surface, what's the difference between the function of fibrocartilaginous zone and the function of articular zone? I mean they both withstand the force of movement.

Fibrocartilagenous zone: Bundles of collagen fibres arranged in crossing pattern and some in radiating pattern. Function- resist against compressive or lateral forces.

Articular Zone: or superficial zone- composed of fibrous tissue. Fibroblasts scattered in avascular layer of type 1 collagen fibres arranged in bundles oriented parallel to articular surface. Connective Tissue contains cartilagenous cells.

Please share some good sources from where you are reading this information. Will help all of us..........

 

[ddsaspi]

Hey ur explanation was awesome........ Can you tell me source.

I have one more question?

What is present beneath the fibrocartilage in the condyle?
Is it dense fibrous connective tissur
Or bone

Please answer. Exam in 15 days




Here goes.. my exam is coming too.. all the best to you too!!

the superficial most layer is deep fibrous connective tissue, beneath which is proliferative zone, and further down is fibrocartilage... Under this lies the calcified cartilagenous zone containing dead or hypertrophied chondrocytes, which may differentiate into bone cells..

Beneath these 4 layers lies Subarticular Bone i.e bone(condyle) ensues

hope it helped!

 

[life easy]

Hey perfect.....Awesome.......Wish you all good.

I have one more doubt.....
Which is the most common type of lung cancer?
Squamous cell carc
Adenocarcinoma

Decks 2009 says it is adenocarcinoma, but many ASDA papers say that it is anenocarcinoma
Pls clear it

Hey ur explanation was awesome........ Can you tell me source.

I have one more question?

What is present beneath the fibrocartilage in the condyle?
Is it dense fibrous connective tissur
Or bone

Please answer. Exam in 15 days





Here goes.. my exam is coming too.. all the best to you too!!

the superficial most layer is deep fibrous connective tissue, beneath which is proliferative zone, and further down is fibrocartilage... Under this lies the calcified cartilagenous zone containing dead or hypertrophied chondrocytes, which may differentiate into bone cells..

Beneath these 4 layers lies Subarticular Bone i.e bone(condyle) ensues

hope it helped!

 

[ibeflossin]

Hey perfect.....Awesome.......Wish you all good.

I have one more doubt.....
Which is the most common type of lung cancer?
Squamous cell carc
Adenocarcinoma

Decks 2009 says it is adenocarcinoma, but many ASDA papers say that it is anenocarcinoma
Pls clear it
__________________

Adenocarcinoma (bronchial) = most common lung cancer in nonsmokers & females.

SCC is linked to smoking, and parathyroid-like activity.

Lung cancer = most common PREVENTABLE cancer, so I would deduce that SCC = most common cancer & adenocarcinoma is most common lung cancer in the non-risk populations.

The answer would depend on the population and risk factors. Keep in mind that ASDA papers may be very old. There are a lot of dynamic things in medicine (such as incidence rates) that you should be aware of and keep up to date with as they may be different in 2010 than 30 years ago. Hope this helps.

 

[ddsaspi]

Hey perfect.....Awesome.......Wish you all good.

I have one more doubt.....
Which is the most common type of lung cancer?
Squamous cell carc
Adenocarcinoma

Decks 2009 says it is adenocarcinoma, but many ASDA papers say that it is anenocarcinoma
Pls clear it





I second the above explanation, just and addition..
Of all primary lung tumors .. most are bronchogenic. among these the most common is

Adenocarcinoma incidence is 35%
Sq. cell Ca. 30%
Small cell formerly k/a Oat cell 20%
and large cell 10%
another subset of adenocarcinoma, is BRONCHOALVEOLAR Ca,5% incidence.

as mentioned above the info matches all sources we have used.. ASDA, decks Kaplan lecture notes..

 

[pistolpete007]

this may be a dumb question....but i thought tmj was fibrocartilage...why are u guys saying if an infant or adult it's dense fibrous connective tissue......


also they synovial membrane does have macrophages right

 

[ibeflossin]

this may be a dumb question....but i thought tmj was fibrocartilage...why are u guys saying if an infant or adult it's dense fibrous connective tissue......


also they synovial membrane does have macrophages right

We are talking about the DISC if you read above.