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Histological structure of TMJ

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by

Trevina Younan

on 7 May 2014

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Transcript of Histological structure of TMJ

Histological structure of TMJ
- The articular surface of
most
of the
synovial joints
are covered by a

hyaline cartilage.
Histological structure of the condyle of a child
*Hypertrophic chandrocytes secrete
collagen type X

and express

increased level of alkaline phosphatase activity
and they also release
matrix vesicles
.

* Then

hypertrophy condrocytes

enter

apoptosis

( programmed cell death )
Endrochondral ossification process involves
a-
Vasularization
and
mineralization
of the
cartilage matrix
and subsequent
degeneration
of the
chondrocytes.
b-
Resorption
of part of the part of the
calcified cartilage

by osteoclasts.

c-
Deposition
of
woven bone
around the template of calcified cartilage by
osteoblast cells.
d- Formation of
mature bone
.
Histological structure of the condyle of an adult
Lined by
same layers
of the
child

TMJ

except:
* Bone is composed of
cancellous bone
covered by a thin layer of
compact bone.
The articular part of the temporal bone
They are
covered by
the
same layers

covering the head of the condyle

except:
The articular disk
The disk is composed of
dense collagenous fibrous tissue
.
- The

TMJ

is the

only

synovial its articular surface is joint covered by a layer of

fibrous tissue
.

- The
hyaline cartilage
is present but it is located inside the

condyle

as a center of ossification and growth, during childhood and young adult.
Hyaline cartilage
Fibrous tissue
Presented by :
Trevina Younan Botros
140
Histological Structure of TMJ
- Under the fibrous layer, there is a

proliferative layer

of

active undifferentiated cells.
These cells divide and differentiate into

chondrocytes
, forming a

secondary condylar cartilage (hyaline)
.
The chondrocytes

hyperatrophy

at the

site of endochondral ossification.
- The condyle of a child is lined by a layer of

fibrous tissue even thickness

formed of
collagen fibers
containing

fibroblast

and

few chondrocyte cells

covering the articular surface.
c
Zone of hypertrophy of chondrocytes
proliferating chondrocytes
hypertrophic chondrocytes
Thank You
for your concenctration
Pre-apoptic cell
Early apoptic cell
Late apoptic cell
* The
trabeculae
of cancellous bone are grouped in such a way that they
radiate
from the
neck of the mandible
and reach the
cortex at right angles.
This arrangement
(fan shaped)
gives the condyle
maximum strength.
* The
red marrow
in the condyle is of a
cellular type
.
In
old individuals
the red marrow is replaced by
fatty marrow.
The glenoid fossa and the articular eminence:
1- The
articular surface
of
glenoide fossa
is covered by a
thin
layer of fibers
and
compact and cancellous bone.
2- The
articular eminence
is covered by a
thick
layer of fibers
and
compact and cancellous bone.
3- The fibrous covering the articular surface arranged into 3 zones:
- The outer zone:
fibers are
parallel
to the bone surface.
- The inner zone:
are
perpendicular
to the bones.
- The intermediate zone:

fibers are
oblique
to the bone surface.
* In the
thin middle portion,
the fibers run mainly in a
wavy anteroposterior direction.
* In the
thick anterior and posterior portions,
the fibers formed
prominent bundles
running
anteroposteriorly, transversely and superinferiorly.
* The wavy coarse of the fibers is indicative of
tensional loads.
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